Engineering, Japan
Engineering, Japan

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Yamaguchi T.,Nikken Sekkei Ltd. | Katsura T.,Hokkaido University | Nakamura Y.,Nippon Steel and Sumikin Engineering
Journal of Environmental Engineering (Japan) | Year: 2015

The authors established a technique for measuring calorie output from a variable refrigerant flow air conditioning system by applying the refrigerant enthalpy method. In this paper, the advantages of the measuring technique and its detailed estimation process of the calorie output are introduced. In addition, the measurement with water cooled variable refrigerant flow air conditioning system was carried out in order to confirm the accuracy of technique. In this actual measurement, it was shown that measuring the appropriate pressure of refrigerant in the heat pump is important to achieve the measurement accuracy. As the another results of actual measurement, the error of estimation values of heat quantity between the established technique and the conventional one is less than 20 % for cooling and heating, respectively. Therefore, the technique for measuring calorie output that the authors established has the high measurement accuracy. In addition, the authors suggested operation improvement method by analyzing measured values such as pressure, calorie output, electric power consumption and so on. As the results, it was confirmed that COPs is improved in the cooling period by lowering the high side pressure of refrigerant in the heat pump depending on the inlet water temperature in the primary side of the pump.

Watanuki T.,Nikken Sekkei Ltd | Takahashi H.,Kanagawa Institute of Technology | Irikura T.,Shibaura Institute of Technology
Journal of the Illuminating Engineering Institute of Japan (Shomei Gakkai Shi) | Year: 2015

Recently, research has been done from various directions to evaluate the brightness of spaces. However, no studies have been conducted regarding quantitative measurements of the brightness at different positions in a visual field. That is, a model for evaluating the brightness of spaces and lighting design techniques have not been considered much regarding the brightness at different positions in the visual field. Therefore, in this study, the sensitivity to brightness at different positions in the visual field was investigated in order to quantify brightness perception throughout the entire visual field. The experimental results show the tendency for Lm/Lt rises as the visual angle increases. Moreover, they show the Lm/Lt in the vertical lower direction is higher than that in other directions, especially at 20 degrees or more.

Honma M.,Nikken Sekkei Ltd. | Kawase T.,Chiba University
Journal of Light and Visual Environment | Year: 2011

In a system that automatically adjusts the slat angles of horizontal blinds, it is possible to allow skylight in while shielding direct sunlight. This can lead to good energy savings since it can reduce the need for artificial lighting without increasing the air-conditioning load. Our research has previously demonstrated this effect of reducing the amount of energy consumed by artificial lighting by controlling the blind slate according to the amount of skylight in an existing office building. However, it was confirmed that the occupants were dissatisfied with the system since it controlled the blinds to shut even though toe occupants observed no direct sunlight and they could not clearly see out the windows. Therefore, this study was conducted with the aim of setting threshold values between the existence and non-existence of direct sunlight based on daylight conditions, so that the automatic controlling of blind slat angles would be ceased to allow slats open when they do not need to block direct sunlight.

Yasunaga J.,Jfe Holdings | Yamaguchi T.,Nikken Sekkei Ltd. | Uematsu Y.,Tohoku University
Journal of Wind Engineering | Year: 2016

The present paper investigates the buckling and vibration behavior of open-topped oil-storage tanks under wind loads based on a finite element analysis. Focus is on the effects of wind girders on such behavior. The wind force coefficients obtained in a turbulent boundary layer is used in the analysis. From the results of buckling analysis, the effects of top/intermediate wind girders on the buckling load and mode of tank shells are made clear. Furthermore, the effect of wind force distribution on the buckling load is discussed based on the results obtained from wind tunnel experiments with two or three tank models in in-line arrangement. A time-history analysis is also carried out in order to investigate the effect of the rigidity of wind girders on the vibration of tank shells. The stresses involved in the tank walls are found to be fairly small, provided that the wind girders are relatively rigid. Finally, the design recommendations of wind girders installed on an open-topped oil storage tanks are proposed, which provide more reasonable design criteria for the wind girders than the current guidelines.

Shinomiya N.,Kobe University | Takada S.,Kobe University | Ushio T.,Nikken Sek Kei Ltd.
Journal of Environmental Engineering (Japan) | Year: 2015

In winter, environmental problems caused by the stack effect occur in high-rise buildings. In order to prevent the stack effect, it is necessary to estimate the behavior of the natural ventilation quantitatively for a whole building. In this study, we measured pressure difference at elevator doors in an actual building through one winter, and at the same time, the numerical analysis by the airflow network model were performed. As the results, the calculated pressure differences at the elevator door on the top and bottom floor showed good agreement with the measured values for both mghttime and commuting time.

Kuwayama K.,University of Kitakyushu | Shiraishi Y.,University of Kitakyushu | Iida R.,Nikken Sekkei Ltd.
Ventilation 2015 - Proceedings of the 11th International Conference on Industrial Ventilation | Year: 2015

It is necessary to simulate both the air-conditioning unit and the indoor environment. Sensing the thermal environment in working spaces is problematic for controlling HVAC systems. Because workers usually remain near their desk, the thermal environment should be measured around desks. However, air temperature is measured on the wall or inlet of air-conditioning units. In addition, indoor thermal environments should be evaluated by using voting systems to include the effects of factors such as air temperature and mean radiant temperature, and relate this to the performance of cooling and heating systems; however, there are few studies of this type of evaluation. In this study, we conducted case studies of the coupled simulation of the integrated energy simulation tool BEST and CFD analysis by a two-node thermoregulation model (2NM) as air-conditioning sensors for office space. The validity of the coupled simulation model was demonstrated by comparison with the indoor thermal environment and air-conditioning heat load measured by air temperature sensors on the wall surface. The indoor thermal environment and air-conditioning heat load depended on the location and method of sensing. The validity of air-conditioning control by installing 2NM in a task region was demonstrated. In future work, we will create a coupled simulation model reproducing office space in detail.

Shinomiya N.,Kobe University | Takada S.,Kobe University | Ushio T.,Nikken Sekkei Ltd.
Energy Procedia | Year: 2015

In winter, the stack effect causes problems in high-rise buildings. In order to prevent it, it is necessary to clarify significant factors influencing ventilation behaviors for whole building. In this paper, the pressure differences at elevator doors were measured through one winter for an actual high-rise building in use. Furthermore the correlation of pressure differences with the parameters such as time, the temperature differences between elevator shafts and outdoor air and the outdoor wind velocity was studied. It was suggested that opening of entrance and elevator doors might influence significantly pressure differences, and thus the ventilation behavior of whole building. © 2015 The Authors.

Kashima Y.,University of Kitakyushu | Shiraishi Y.,University of Kitakyushu | Iida R.,Nikken Sekkei Ltd. | Tsukami S.,Nikken Sekkei Ltd.
Ventilation 2015 - Proceedings of the 11th International Conference on Industrial Ventilation | Year: 2015

In this study, we verify the performance of indoor environment by evaluating the thermal and air environment in detail in the hospital mall with floor radiant and under floor air-conditioning (A/C) system, based on CFD analysis. Therefore, we clarify the characteristic of this system by comparison with wall supply AC system (package A/C system). The following results were obtained: (1) According to the results of CFD analysis for this space, uniform indoor thermal environment was confirmed by using both floor radiant and under floor cooling system. (2) Combined application of floor radiant and under floor cooling system in large space was suggested that was useful about thermal environment and energy saving in comparison with wall supply A/C system.

Yamane T.,Nikken Sekkei Ltd. | Nagahashi S.,Chiba Institute of Technology
Journal of Structural and Construction Engineering | Year: 2010

The purpose of this paper is to present a superposition technique for seismic waves from consecutive earthquakes. Seismic waves from each earthquake are synthesized by the waveform generation methods proposed in previous papers. The consecutive seismic waveforms are superposed so as to match the positions on the time history axis with respect to a wave arriving from the border between fault planes, considering the relationship between the distribution of phase differences and the time history of the accelerogram. By analyzing the dynamic behavior of high-rise buildings using the proposed superposition technique, it is indicated that a proper evaluation of ground motions is important in the case of consecutive earthquakes.

Kobori T.,Nikken Sekkei Ltd. | Konishi A.,Nikken Sekkei Ltd.
Proceedings of the 13th East Asia-Pacific Conference on Structural Engineering and Construction, EASEC 2013 | Year: 2013

This paper describes the structural design of TOKYO SKYTREE® which was completed in May last year. This tower is the world's highest freestanding steel tower, and it was planned to be the central facility for digital broadcasts in the Tokyo area. Structures in Japan are required to be sufficiently safe against the severe natural environment of Japan, which include not only earthquakes but also typhoons. This tower is also to serve the important role of distributing information during disasters, so even more severe criteria were provided for its design. The following is an introduction to the structural design of TOKYO SKYTREE, which satisfies the strict design conditions using a unique The Core Column System, vibration control system.

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