• Structural Engineering and Mechanics
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• 제86권5호
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• pp.647-661
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• 2023

It is recognized that the installation of energy dissipation devices, such as the tuned mass damper (TMD), decreases the dynamic response of structures, however, the best parameters of each device persist hard to determine. Unlike many works that perform only a deterministic optimization, this work proposes a complete methodology to minimize the dynamic response of footbridges by optimizing the parameters of multiple tuned mass dampers (MTMD) taking into account uncertainties present in the parameters of the structure and also of the human excitation. For application purposes, a steel footbridge, based on a real structure, is studied. Three different scenarios for the MTMD are simulated. The proposed robust optimization problem is solved via the Circle-Inspired Optimization Algorithm (CIOA), a novel and efficient metaheuristic algorithm recently developed by the authors. The objective function is to minimize the mean maximum vertical displacement of the footbridge, whereas the design variables are the stiffness and damping constants of the MTMD. The results showed the excellent capacity of the proposed methodology, reducing the mean maximum vertical displacement by more than 36% and in a computational time about 9% less than using a classical genetic algorithm. The results obtained by the proposed methodology are also compared with results obtained through traditional TMD design methods, showing again the best performance of the proposed optimization method. Finally, an analysis of the maximum vertical acceleration showed a reduction of more than 91% for the three scenarios, leading the footbridge to acceleration values below the recommended comfort limits. Hence, the proposed methodology could be employed to optimize MTMD, improving the design of footbridges.

• KIEAE Journal
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• 제15권1호
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• pp.97-102
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• 2015

Recently many buildings are airtight, deterioration takes the high stage. As this room ventilation is increasingly difficult, the importance of indoor air was emphasized. And Got a few provisions on the indoor ventilation, the building is used for other purposes also requires a lot of careful research. In this study, consisting of floor heating ventilation in the room and wants to know the impact on the human body react with the carbon dioxide concentration in the indoor air were investigated PMV. We have get the data through the experimental study like this. It can be inferred correlations of ventilation and temperature according to human comfort that you should consider when using the work of residential buildings in accordance with the changing social conditions and social. It is also determined that in the future through additional experiments related data can be established basic experimental data.

• 한국지역사회생활과학회지
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• 제25권4호
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• pp.487-494
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• 2014

This study investigates thermoregulatory behaviors of obese children for their thermal comfort. Nine normal-weight children (NWC) and nine obese children (OC) participated in the study. All subjects were fourth-graders and sixth-graders in elementary school. An informed consent form was obtained from each child and his or her mother. The questionnaire method was used, and the experiment was conducted to determine the preferred amount of clothing at $17^{\circ}C$ and the preferred temperature at $33^{\circ}C$. According to the results, OC were more susceptible to heat than NWC, whereas there was no significant difference in their susceptibility to cold. There were no significant differences of the oral temperature and the mean skin temperature between the two groups, but changes in forearm blood flow were less in OC than in NWC. There was no significant difference in the preferred amount of clothing between OC and NWC, and the preferred temperature was higher in NWC than in OC. The results based on the questionnaire are consistent with those based on the experiment. A compositive study of physical exercise, eating behavior, and wearing behavior should be useful for developing programs for preventing and treating obese children.

• 설비공학논문집
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• 제27권11호
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• pp.596-602
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• 2015

In this study, experiments using bioelectronic signals and questionnaire surveys were carried out in learning conditions when temperatures changed from low- and high-uncomfortable to comfortable. As a result, the stress factor Photoplethysmography (PPG) decreased, while the Root Mean Square of Standard Deviation (RMSSD) of PPG increased when the indoor temperature was changed from low- or high-uncomfortable to comfortable. Additionally, the absolute power of the ${\alpha}$-wave in the brain increased. According to the analysis of the association between the questionnaire and bioelectronic signals, the standard deviation of the stress factor as measured by pulse was closely related to the result of the thermal sensation questionnaire. In addition, it was found that the concentration on studying improved under comfortable temperatures when compared to uncomfortable temperatures.

• 설비공학논문집
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• 제18권1호
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• pp.1-6
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• 2006

This study was performed to evaluate sleep efficiencies and conditions for comfortable sleep based on the analysis of EEGs and MST under four thermals conditions. Five female subjects who have similar life cycle and sleep patterns were participated for the sleep experiment. Their age was from 20 to 22 years old. They were healthy, and had regular sleep with consistent bed and wakeup time. It was checked whether they had a good sleep before the night of experiment. Experiments were performed in an environmental chamber of $4.1\times4.9\times2.7m$ size. EEGs were obtained from C3-A2 and C4-Al electrode sites. Sleep stages were classified, then TST, SWS latency and SWS/TST were calculated for the evaluation for sleep efficiencies on thermal conditions. As results, it was concluded that indoor thermal environments of $24\~26^{\circ}C$ was the best for comfortable and deep sleep.

• 한국감성과학회:학술대회논문집
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• 한국감성과학회 2001년도 춘계학술대회 논문집
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• pp.194-199
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• 2001

쾌적한 스포츠웨어는 기능성에 있어서 자연환경의 변화조건과 인체의 운동 및 활동에 맞추어 열절달 및 수분전달 등을 적절히 조절할 수 있어야 한다. 이에 본 연구에서는 일반환경조건 및 강우환경조건하에서의 형상기억 투습방수직물 소재의 스포츠웨어 착용에 따른 인체생리반응 및 쾌적감을 규명하기 위하여 스포츠웨어를 제작하여, 인공기후실에서 환경조건변화에 따른 온열생리학적 특성 및 주관적 감각을 측정, 그 특성을 비교, 고찰하였다. 평균피부온은 강우환경조건에서 온도가 낮게, 변동폭이 많게 나타났다. 변화경향을 운동부하를 기점으로 온도의 상승이 나타났고, 운동 2단계에 가장 높은 온도를 나타냈으며, 이후 감소하였다. 직장온은 일반환경조건에 비해 강우환경조건에서 온도의 미세한 상승을 보였다. 의복내 기후는 두 조건 모두에서 가슴부위보다 등부위의 온·습도의 변동폭이 크게 나타났고, 강우환경조건에서의 의복내 온도를 제외하고는 모두 등부위의 온·습도가 높게 나타났다. 최고 혈압은 운동의 강도에 따라 비례하여 상승하고, 최저 혈압에는 큰 영향없이 나타났으며, 변화경향은 의복내 온도의 경향과 역으로 나타났다. 평균혈압은 일반환경조건에서 6.9mmHg 높게 나타났다. 심박수는 일반환경조건에서 4.4beats/min 높게 나타났다. 강우환경조건의 주관적 감각의 평가에서, 신체에 직접 가해지는 빗물 등으로 인해 불쾌감이 증가하였고, 운동 후에는 일반환경조건과 달리 냉감이 증가하였으며, 습윤감은 최고치에 달하였다.

• 한국의류학회지
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• 제13권3호
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• pp.295-303
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• 1989

This study is to measure the thermal resistance of 7 types of Parka of different materials with thermal manikin and to compare their effects on physiological responses & subjective wear sensations. Following are the results obtained from the experiments 1) From the thermal manikin experiment, i) As an outer layer, although not significant, water proof fabric was warmer than water proof-vapor permeable fabric. ii) In case of insulating material, down was better for thermal resistance than polyester wadding of the same thickness. Moreover, as the down was thicker, it had more efficiency in thermal resistance. However, the marginal efficiency of thickness was found to be decreasing. 2) From the male-subject experiments, i) Chest temperature, mean skin temperature & microclimate temperature showed the same results on thermal resistance as those of the thermal manikin experiment. ii) Only during rest periods, there was a significant difference among 5 insulating materials in the sense of microclimate humidity. The almost same conclusion was obtained from the above experiments. Even the outer layer did not significantly affect thermal resistance & subjective wear sensation, insulating materials had a significant influence upon them. But in case of 3.5 cm down, it gave less comfortable than that of the thinner. Therefore the optional one for the best comfort & thermal resistance among 7 combinatins is the outer layer of water proff-vapor permeable & insulating material of 2.1 cm down.

• 한국생활과학회지
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• 제11권2호
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• pp.189-196
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• 2002

The purpose of this study were to elicit the attitudes toward underwear, to compare the difference according to the demographic variables, and to find the relationship between the attitudes toward underwear and social-psychological characteristics of university female students in Cheongju city. The questionnaires were to measure the attitudes toward underwear, the demographic information, and social-psychological characteristics. As statistical analysis, frequencies, mean, t-test, F-test, factor analysis, and correlation were used. The results were as follows: 1) The female students regarded tactile sensation of underwear fabrics as the important element in their attitude toward underwear, while they showed a little interest about gorgeous underwear style. 2) The freshman students have strongly. fixed ideas about the under wear, the other(sophomore, junior, senior) students showed more interest in decorative and fashionable aspects of underwear. 3) The attitudes toward underwear were classifies into six factors; intension about high quality, decorative design, stereotype, immodesty, style and comfort. 4) There were partially significant differences according to demographic variables in the attitudes toward underwear. 5) Also, there were significant correlations between the social-psychological characteristics and the attitudes toward underwear.

• 한국생활과학회지
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• 제15권4호
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• pp.647-650
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• 2006

The factors affecting clothing comfort are temperature, humidity, and air velocity of clothing microclimate which is the temperature and the humidity between the skin surface and the innermost garment, clothing pressure and clothing texture to the skin. This study was designed to estimate the distribution of clothing microclimate on the upper body. All the data of this study were collected from volunteered male subjects in the controlled climate chamber laboratory in which the temperature was $25\pm1^{\circ}C$, the relative humidity $50\pm5%$, and the air velocity 30cm/sec. All subjects should wear long-sleeved inner wear and pants woven in 100% cotton. Clothing microclimate temperature at 16 sites on the chest and 16 sites on the back was measured. The results were as follows: the distribution of the clothing microclimate temperature on the upper body was $30.6\sim34.7^{\circ}C$ on the breast and $31.5\sim35.4^{\circ}C$ on the back. While a mean temperature on the chest was 33.3$^{\circ}C$, it was 33.1$^{\circ}C$ on the back.

• Architectural research
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• 제19권3호
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• pp.71-77
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• 2017

Dynamic pricing refers to a system in which a tariff varies, according to a level of charging and applied time depending on time change. The power billing system used in the Korean Electric Power Corporation (KEPCO) is based on time of use (TOU) pricing, which is one of the dynamic pricing systems. This paper aimed to determine the operational results of a variable refrigerant flow system, to which a new control algorithm was applied, in order to respond to dynamic pricing, in summer and the utility of the new control. To do this, real measured data was acquired from a VRF system installed in a building for educational purposes, where dynamic pricing was applied for about 100 days during summer time. At the maximum load operation time period in TOU, the new control minimized operation within the indoor comfort range, an increase in refrigerant evaporation temperature in the indoor unit and the number of revolutions in a compressor in the outdoor unit was limited. As a result, power usage was decreased by 11%, and the operational cost by 14.6%. Furthermore, measurement results using the Predicted Mean Vote (PMV) model, that represented satisfaction of thermal environment, showed that 82.8% to 90.4% of the occupants of the building were satisfied during operation when the new control was applied.