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FUJITA Kouji

    Department of Human Factors Engineering and Environmental Design　Associate Professor
Last Updated :2024/04/25

Researcher Information

URL

J-Global ID

Research Interests

  • 健康   断熱   床下暖房   蓄熱   潜熱蓄熱   換気   

Research Areas

  • Social infrastructure (civil Engineering, architecture, disaster prevention) / Construction environment and equipment

Academic & Professional Experience

  • 2023/04 - Today  Kindai UniversityFaculty of Biology-Oriented Science and Technology Department of Human Factors Engineering and Environmental Design准教授
  • 2017/04 - Today  KINDAI UNIVERSITY生物理工学部 人間環境デザイン工学科Lecturer
  • 2014/04 - 2017/03  Kindai UniversityFaculty of Biology-Oriented Science and Technology講師
  • 2008/04 - 2014/03  Kobe University工学(系)研究科(研究院)助教

Published Papers

  • Koji FUJITA; Atsushi IWAMAE; Yutaka SATO; Risako KUMAKIRI
    Journal of Environmental Engineering (Transactions of AIJ) Architectural Institute of Japan 87 (801) 722 - 730 1348-0685 2022/11 [Refereed]
  • Koji Fujita
    Thermal Science and Engineering Progress Elsevier BV 30 101275 - 101275 2451-9049 2022/05 [Refereed]
  • Koji FUJITA
    AIJ Journal of Technology and Design Architectural Institute of Japan 26 (63) 608 - 612 1341-9463 2020/06 [Refereed]
  • PROPOSAL OF METHOD TO ESTIMATE MAXIMUM HEAT LOSS FROM CRAWL SPACE FOR 24 HOUR CONTINUOUS CRAWL-SPACE HEATING BY SUPERPOSITION USING LINEARITY OF HEAT CONDUCTION EQUATION
    Koji Fujita
    日本建築学会環境系論文集 85 (771) 321 - 330 2020/05 [Refereed]
  • PROPOSAL OF MEDICAL COST ESTIMATION METHOD ACCORDING TO THE THERMAL ENVIRONMENT IN HOUSES AND EXAMINATION OF ECONOMICAL THERMAL INSULATION PERFORMANCE OF HOUSES IN CONSIDERATION OF MEDICAL COSTS
    Koji FUJITA; Atsushi IWAMAE; Yutaka SATO; Risako TAKAHARA; Yo SUZUKI
    Journal of Environmental Engineering (Transactions of AIJ) 85 (768) 159 - 167 2020/02 [Refereed]
  • Koji Fujita; Satoshi Matsuoka; Atsushi Iwamae; Noriaki Ota
    AIJ Journal of Technology and Design 25 (60) 753 - 758 2019/06 [Refereed]
  • Koji Fujita; Takayuki Matsushita
    6TH INTERNATIONAL BUILDING PHYSICS CONFERENCE (IBPC 2015) ELSEVIER SCIENCE BV 78 1678 - 1683 1876-6102 2015 [Refereed]
     
    We have conducted this study to find an equation that is capable of predicting the temperature distribution in a semi-infinite phase change material (PCM) that has broad phase-change-temperature range on the condition that the initial temperature distribution is uniform at a lower temperature than the phase-change-temperature, and the surface is kept at a higher temperature than the phase-change-temperature. We found that the temperature distribution in the PCM with broad phase-change-temperature range can be approximated by substituting the lower inflection point temperature of the Gaussian distribution of the apparent specific heat for the phase-change-temperature in the equations that express temperature distribution in the PCM with a specific phase-change-temperature. (C) 2015 The Authors. Published by Elsevier Ltd.
  • Takayuki Matsushita; Masashi Kishiue; Koji Fujita
    Journal of Environmental Engineering (Japan) Architectural Institute of Japan 79 (703) 745 - 751 1881-817X 2014/09 [Refereed]
     
    The approximate analytical solution of the location of smoke front below horizontal ceiling at early time in fire is derived by the handling as the axi-symmetric problem. At first the approximate analytical solution of the average temperature of smoke layer is derived in assuming that the progress velocity of smoke front is proportional to 1/2 power of time based on the mass preservation. Then the integral equation to predict the location of smoke front is derived in this smoke average temperature. As this equation is not able to solve analytically, an approximate analytical equation is derived by approximation of integrand and being subject to temperature less exceeding initial inflow temperature. Particularly, in case of the treatment of center sprang out, the location of smoke front is proportional to 1/2 power at early time then to 3/4 power at time. The prediction is compared to the experimental data. It is shown that the location of smoke front is predicted by the approximate analytical solution.
  • Takayuki Matsushita; Koji Fujita
    Journal of Environmental Engineering (Japan) Architectural Institute of Japan 79 (703) 739 - 744 1881-817X 2014/09 [Refereed]
     
    Traditionally, the smoke front location below the horizontal ceiling of a corridor in fire has been predicted by the numerical analysis. In this paper, an approximate analytical solution is derived. If the progression rate of smoke front is assumed to be constant, the analytical solutions of smoke average temperature and the equation of smoke front location are derived. As the equation of smoke front location is not solved analytically, the integrand of the equation is approximated by 1/At, and on additional condition that the smoke temperature does not exceed the initial inlet temperature the further approximate analytical solution is derived. The final approximate analytical solution shows that the smoke front location is proportional to the time until 1 / A, and expand in proportion to the 2 /3 power of time thereafter. The approximate analytical solution is compared the experimental results of actual size. The result shows that it is possible to predict the smoke front location in considering heat loss from the ceiling and the walls.
  • Koji Fujita; Takayuki Matsushita
    Journal of Environmental Engineering (Japan) Architectural Institute of Japan 79 (697) 241 - 246 1881-817X 2014 [Refereed]
     
    The objective of this paper is to present a new method for estimating air flow coefficients and air flow exponents of air leakage areas not only in the external wall of a house but also in the internal walls between rooms using only one type of tracer gas. These values-which are unknown variables-are determined using nonlinear simultaneous equations, which consist of balance equations for the air mass and tracer-gas concentration in the rooms. To verify the validity of this method, we set up a numerical experiment. As a result of the experiment, it was clarified that the present estimation method yields a reasonable estimate of the air flow coefficients and the air flow exponents.
  • A Method for Estimating Amount of Stored Heat in PCM that Exchange Heat with Flowing Water
    Koji Fujita; Takayuki Matsushita
    Central European Symposium on Building Physics 2013 2013/09 [Refereed]
  • Masashi Kishiue; Takayuki Matsushita; Kouji Fujita; Satoru Takada
    Journal of Environmental Engineering 日本建築学会 77 (673) 115 - 120 1348-0685 2012/03 [Refereed]
     
    In this paper, according to the approach built on previous paper(No.645,pp.1203-1209,2009.11), the relationship of air supply rate between the bulletin requirements in normal temperature and the conventional calculating method based on the condition in fire is constructed. The calculation procedure of air supply rate based on the ventilation calculation in normal temperature to satisfy the bulletin requirement is shown. Then the relationship in general of leakage by the position of air release opening is considered, the appropriate design for the height on floor of the air release opening and the calculation procedure of additional air supply rate to block smoke in fire are shown.
  • Effective Flow Area Estimation Test using CO2
    Ken Iwamoto; Koji Fujita; Takayuki Matsushita
    Proceedings of AIVC International conference 2010 2010/10 [Refereed]
  • Effective Flow Area Estimation Method using a Gas
    Koji Fujita; Ken Iwamoto; Takayuki Matsushita
    Proceedings of AIVC International conference 2010 2010/10 [Refereed]
  • Tomoe Uchibori; Tetsuya Akiyama; Takayuki Matsushita; Koji Fujit; Satoru Takada
    Journal of Environmental Engineering Architectural Institute of Japan 74 (645) 1195 - 1202 1881-817X 2009 [Refereed]
     
    This study examined the pressurization smoke control method in the congregated vertical shaft in case of an underground fire. The pressurization smoke control can secure a refuge route by preventing an invasion of smoke to lobby. The congregated vertical shaft exhaust system is a method to shut smoke out of a room. However, it can happen that smoke exhausted from a lower floor leaks from an exhaust opening of an upper floor congregated vertical shaft. Therefore, in this study, for the purpose of grasping the behavior of the leakage of smoke in congregated vertical shaft with pressurization smoke control system, an equation to determine the rate of smoke leakage from the dimension of the building and the behavior of the fire is shown theoretically. Furthermore, a simple method for the design of the shaft setup height and the shaft cross-section area is proposed from the viewpoint of prevention of smoke leakage.
  • Takayuki Matsushita; Koji Fujita; Masashi Kishiue; Satoru Takada
    Journal of Environmental Engineering Architectural Institute of Japan 74 (645) 1203 - 1209 1881-817X 2009 
    The purpose of this paper is the establishment of the method to confirm at the normal temperature that the pressurization smoke control system is able to block off smoke in case of the fire. A theory is constructed to determine the opening condition of smoke insulation door at the normal temperature which realizes the air flow rate equivalent to that in case of the fire. Although the opening information in the actual building usually does not agree with that in the planning, it is necessary to know the opening information in the actual building. Therefore, in this paper, we propose a procedure to know the opening information by two measurements at normal temperature., and the same time, to judge whether the system is able to block off smoke in case of fire. Moreover the simplified method is proposed for evaluating the performance to block offsmoke only from the measurement ofone case where the door is fully opened door at the normal temperature. As shown in the example, it would be possible to judge the appropriateness of pressurization smoke control system based on the result ofthe measurement at the normal temperature.
  • Experimental Study on Crawl-Space Heating with Thermal Storage using Heat Pump
    Koji Fujita; Atsushi Iwamae; Takayuki Matsushita
    Proceedings of 8th Nordic Symposium on Building Physics 2 527 - 534 2008/06 [Refereed]
  • Koji Fujita; Atsushi Iwamae; Takayuki Matsushita; Hiroshi Nakagawa; Hiroshi Yokoyama; Kyoji Ishizu
    Journal of Environmental Engineering Architectural Institute of Japan 73 (626) 479 - 486 1348-0685 2008/04 [Refereed]
     
    We present a heating system with thermal storage using a heat pump which supplies heat to the thermal storage installed in a crawl space of a residential house insulated at the foundation walls. We used latent thermal storage materials. This system can charge heat by using cheap nighttime electricity and discharge the stored heat at daytime. We showed equations to determine the air volumes of the heat pump and the ventilator, and equations to determine the phase transition temperature and the amount of the latent thermal storage materials to keep the room setting temperature. We constructed a computer simulation program of this heating system and confirmed the validity of these equations.
  • Koji Fujita; Atsushi Iwamae; Takayuki Matsushita; Kyoji Ishizu; Hiroshi Nakagawa
    Journal of Environmental Engineering Architectural Institute of Japan 73 (626) 471 - 478 1348-0685 2008/04 [Refereed]
     
    We present a heating system with thermal storage using a heat pump which supplies heat to the thermal storage installed in a crawl space of a residential house insulated at the foundation walls. We used sensible thermal storage materials. This system can charge heat by using cheap nighttime electricity and discharge the stored heat at daytime. It is revealed by experimental studies that thermal behavior of the room is greatly influenced by the heat capacity of the thermal storage. We constructed a computer simulation program of this heating system and showed the ratio of the stored heat for generated heat by the heat pump with the volume of the thermal storage materials. We showed the way to determine the volume of the thermal storage materials and the capacity of the heat pump.
  • Koji Fujita; Atsushi Iwamae; Takayuki Matsushita
    Journal of Environmental Engineering Architectural Institute of Japan 73 (625) 291 - 297 1348-0685 2008/03 [Refereed]
     
    'Crawl-space heating' is a heating system using the crawl space as a duct for heat transport from a heat pump. The purpose of this study is to grasp the convective heat-transfer coefficient at the slab-concrete surface and the floor-under surface, under the condition of crawl-space heating. When the crawl-space heating is operated, the air velocity in the crawl space is generally 0.05-0.20m/s and the heat transfer is caused by both the forced convection and the natural convection. We measure the convective heat-transfer coefficient by the wind tunnel test. It is revealed that the convective heat-transfer coefficient at the slab-concrete surface is about 1.0-4.0W/m 2K and that at the floor-under surface is about 6.0-10.0 W/m 2K.
  • Koji Fujita; Atsushi Iwarnae; Takayuki Matsushita
    BUILDING SIMULATION 2007, VOLS 1-3, PROCEEDINGS TSINGHUA UNIV PRESS 321 - + 2007 [Refereed]
     
    In this paper, we present a heating system with thermal storage using a heat pump which supplies heat to the thermal storage equipment installed in the crawl space of residential house insulated at the foundation walls. This system can charge heat by using cheap nighttime electricity and discharge the stored heat at daytime. The thermal performance of the heating system and the effects of various factors on it are analyzed through simulation on the premise that a heat pump which has generally spread is used. The main results are as follows: (1) It is possible to control the system efficiently adjusting the lifestyle by change the start time of the operation of the ventilator connected to the thermal storage equipment to discharge the stored heat. (2) Using the latent thermal storage materials, the change of the room temperature can be made moderate.
  • FUJITA Koji; IWAMAE Atsushi; MATSUSHITA Takayuki; KITAGAWA Kenji; HANIBUCHI Haruo
    Journal of environmental engineering Architectural Institute of Japan 71 (607) 65 - 70 1348-0685 2006/09 [Refereed]
     
    In this paper, we report the experimental studies which were carried out in an experimental house with thermal insulation for its foundation walls, concerning (a) the indoor thermal environment and (b) the heat flow in the crawl space to the ground and to the floor, under the condition of crawl space heating. The main results which we obtained are as follows: 1. The temperature in the room ranges from 18 to 21℃, and that of the floor surface becomes over 23℃. 2. When a fan is put in operation in order to control a current of air in the crawl space, the flow of the heat towards the floor increases, but that towards the ground also increases out of the warm air blowing out zone. 3. It is suggested that most of the heat to the ground is brought by radiation from the lining of the floor.

MISC

Research Grants & Projects

  • Japan Society for the Promotion of Science：Grants-in-Aid for Scientific Research
    Date (from‐to) : 2015/04 -2018/03 
    Author : Fujita Koji
     
    ‘Crawl-Space Heating’ is a heating system using the crawl space as a duct for heat transport from a heat pump. It can produce the same environment as floor heating. We proposed design and operation methods of Crawl-Space-Heating for partial and intermittent heating. We derived equations to estimate the maximum heat load in accordance with the target temperature of the room, the outdoor temperature, the heat insulation performance of the house, the thermal resistance of the foundation insulation, the thermal conductivity of the ground, the acceptable preheating time, the heating operation time in a day and the time when the heating operation is started in the morning. Furthermore, we proposed equations to calculate the required preheating time.
  • Japan Society for the Promotion of Science：Grants-in-Aid for Scientific Research
    Date (from‐to) : 2012/04 -2014/03 
    Author : FUJITA KOJI
     
    We derived equations to estimate the temporal change in the amount of stored heat in phase change material (PCM) that exchange heat with flowing water. There are two types of PCM concerning the range of the phase-change temperature. One has the range, and the other doesn't have the range. We derived the equations for the both types of the PCM. No rigorous analysis has been carried out for these cases. Therefore, we considered methods to obtain approximate solutions based on a number of approximations. By visualizing the approximate analytical results and comparing them with the numerical simulation results, we checked the applicability of the approximate analytical results as the equations to estimate the temporal change in the amount of stored heat in the PCM.
  • Japan Society for the Promotion of Science：Grants-in-Aid for Scientific Research
    Date (from‐to) : 2009 -2010 
    Author : FUJITA Koji
     
    We found a new method for estimating effective flow areas not only in the external wall of a house but also in the internal walls between rooms using only one type of tracer gas. The discharge coefficient of each wall and the pressure in each room-which are unknown variables-are determined using nonlinear simultaneous equations, which consist of balance equations for the air mass and tracer-gas concentration in the rooms.

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