• 대한설비공학회:학술대회논문집
• /
• 대한설비공학회 2006년도 하계학술발표대회 논문집
• /
• pp.879-884
• /
• 2006

Jinan Poonghyeol in Chonbuk province Is famous for emitting cool air in summer and warm air in winter. Cause for these phenomena is studied by measuring temperature, humidity and air velocity of several locations around Jinan Poonghyeol Temperature variations under the ground are also measured. Analyzing data compiled from July 21, 2005 through May 26, 2006, it is presumed that storage effect of rocks and soil in this area and buoyance effect are the main causes for this mysterious natural air-conditioning phenomena.

• 한국의류학회지
• /
• 제41권5호
• /
• pp.929-938
• /
• 2017

This research investigated the effects of cool touch fabrics on thermo-regulating physical properties and subjective evaluation using a 3D fitted women's T-shirts in wear test. Qmax, clothing microclimate, microclimate wettedness, thermogram and subjective vote were observed during rest-right after an exercise-rest protocol. As a result, there was no single determining physical variable to explain the reasons of cool sensations of T-shirts made of cool touch fabric across the entire protocol. Qmax could partly predict a wear sensation at the initial stage when only insensible perspiration was presented. Simultaneous observation of temperature/humidity gradient understand from the inside to the outside of the clothing layer or microclimate wettedness calculated using vapor pressure were helpful to figure out the performance of cool touch fabric, especially at the later stage of the protocol when sweating was excessive. It was especially difficult to connect thermo-regulating physical variables to the subjective evaluation during transient conditions such as 'right after exercise' stage. It is necessary to measure the amount of heat and moisture transferred from the skin to the outside of clothing along with the physical properties measured in this study to understand the detailed mechanisms of why a cool sensation is evoked from tight fitting T-shirts made of newly developed cool touch fabrics.

• 한국의류학회지
• /
• 제14권2호
• /
• pp.152-163
• /
• 1990

The purpose of this study is to experimentally analyze the relationship between structural characteristics of cotton fabrics and their cool-and-warm felling in order to develop more comfortable fabrics. Comfort in textile products has been emphasized as consumers preferred performance to fashion of clothing. Thermal comfort of clothing is a basic parameter of the comfort sensation which is usually represented by the cool-and-warm feeling felt by human skin. Cloo-and-warm feeling is perceived by the heat flux which transfers heat energy stored in an object to skin. We feel warm (cool) if the temperature of nerve extremity in skin ascends (descends). As cool-and-warm feeling determines the comfort sensation of clothing, it is important to develop new comfort fabrics. Although considerable works have been made on the body, clothing, and environment, there has been no research study on the structural characteristics of fabrics and their cool and warm feeling. Cool-and-warm feeling is closely related to the transient heat transfer property. This research study used the cotton fabrics manufactured in Korea as sample and measured $q_{max}$ value with thermal property measuring instrument (Thermo-Labo II type). $q_{max}$ values estimated by polynomial regression equation were compared with those observed in this study. This study also identified the structural parameters of cotton fabrics for a specific range of $q_{max}$ values. The findings of this study can be summarized as follows: 1) As the thickness, porosity and air permeability of cotton fabrics increase, $q_{max}$ value decreases. 2) As the fabric count and over factor of cotton fabrics increase, $q_{max}$ value also increases. 3) $q_{max}$ values have been estimated by simple and polynomial regression equations developed in this study. Regression curves which have been plotted by polynomial regression equations also provided with the range of structural parameters for a specific range of $q_{max}$ values of cotton fabrics. This study would be significant in that it has identified the structural Parameters for the cool-and-warm feeling of cotton fabric at $65\%$ relative humidity.

• Nuclear Engineering and Technology
• /
• 제33권5호
• /
• pp.498-513
• /
• 2001

Performed here is a comparative assessment study for the generation of the pressure- temperature (P/T) limit curve of the reactor vessel. Using the cooling or heating rate and vessel material properties, the stress distribution is obtained to calculate stress intensity factors, which are compared with the material fracture toughness to determine the relations between operating pressure and temperature during cool-down and heat-up. P/T limit curves are generated with respect to crack direction, clad thickness, toughness curve, cooling or heating rate and neutron fluence, and their results are compared.

• 한국정밀공학회지
• /
• 제25권4호
• /
• pp.100-107
• /
• 2008

Bellows is an important component in Joule-Thomson cryocooler, which minimize the excessive flow of the cryogenic gas. The bellows is made of Monel 400 and its geometry is an axial symmetric shell. During cool-down process, the pressure and volume within bellows must be satisfied with Benedict-Webb-Rubin state equation. Moreover, Poisson's ratio of Monel 400 is nearly constants, but its Young's modulus varies for a drop in temperature. Under these conditions, bellows contracts in the axial direction like a spring. To evaluate deformation of bellows at cryogenic temperature, the numerical calculation of the volume within bellows and finite element analysis are iteratively used in this research. the numerical results show that deformation of the bellows is approximately linear for change of temperature.

• Structural Engineering and Mechanics
• /
• 제14권2호
• /
• pp.191-208
• /
• 2002

A comparative assessment study for a generation of the pressure-temperature (P-T) limit curve of a reactor vessel is performed in accordance with ASME code. Using cooling or heating rate and vessel material properties, stress distribution is obtained to calculate stress intensity factors, which are compared with the material fracture toughness to determine the relations between operating pressure and temperature during reactor cool-down and heat-up. P-T limit curves are analyzed with respect to defect orientation, clad thickness, toughness curve, cooling or heating rate and neutron fluence. The resulting P-T curves are compared each other.

• 한국잡초학회지
• /
• 제15권2호
• /
• pp.166-174
• /
• 1995

한지형(寒地型) 잔디의 하고원인(夏枯原因)을 탐색(探索)하기 위하여 난지형(暖地型)잔디 7종(種) 9품종(品種)과 한지형(寒地型)잔디 5종(種) 28품종(品種)에 관해 광합성(光合成), 광호흡(光呼吸) 및 암호흡(暗呼吸)의 온도변화(溫度變化)에 따른 반응(反應)을 조사(調査)한 결과(結果)를 요약(要約)하면 다음과 같다. 1. 생체중당(生體重當) 외견상(外見上) 광합성(光合成) 속도(速度)의 평균치(平均値)는 난지형(暖地型) 잔디가 13.09 mg $CO_2$/g/h, 한지형(寒地型) 잔디가 7.75 mg $CO_2$/g/h로 난지형(暖地型)이 2배(倍) 정도(程度) 높았으나, 한지형(寒地型) 잔디중에서도 Creeping bentgrass는 난지형(暖地型)의 kikuyugras나 Bahiagrass보다 높았다. 2. 외견상(外見上) 광합성(光合成) 속도(速度)와 온도(溫度)와의 관계(關係)를 보면 난지형(暖地型) 잔디는 $30^{\circ}C$, 한지형(寒地型)잔디는 $25^{\circ}C$에서 가장 높은 값을 나타내었다. 3. 광호흡속도(光呼吸速度)의 지표(指標)가 되는 $CO_2$ 보상점(補償点)의 평균치(平均値)는 난지형(暖地型)잔디에서 29.5 ppm, 한지형(寒地型)은 75.6 ppm이었는데, 난지형(暖地型) 잔디의 경우 온도(溫度)가 $25^{\circ}C$에서 $40^{\circ}C$까지 상승(上昇)하여도 크게 증가(增加)하지 않았으나, 한지형(寒地型)잔디는 온도(溫度)의 상승(上昇)에 따라 $CO_2$ 보상점(補償点)의 증가(增加)가 현저(顯著)하였으며, $25^{\circ}C$에서 $40^{\circ}C$ 범위(範圍)까지 온도(溫度)가 상승(上昇)하면 평균(平均) 50% 이상(以上) 높아졌다. 4. 암호흡속도(暗呼吸速度)는 온도(溫度)가 상승(上昇)함에 따라 높아졌으며, 어떤 온도조건하(溫度條件下)에서도 한지형(寒地型) 잔디가 난지형(暖地型) 잔디에 비하여 높았으나 온도상승(溫度上昇)에 따른 암호흡속도(暗呼吸速度)의 증가율(增加率)은 양자간(兩者間)에 차(差)가 없었다. 5. 다른 온도조건하(溫度條件下)에서 $CO_2$의 수지(收支)를 외견상(外見上) 광합성속도(光合成速度)와 암호흡속도(暗呼吸速度)를 기초(基礎)로 해서 구해 보면 난지형(暖地型)과 한지형(寒地型)모두 온도(溫度)의 상승(上昇)에 따라 $CO_2$의 수지(收支)는 낮아지는 경향(傾向)이었지만, 그 정도(程度)는 한지형(寒地型) 잔디가 난지형(暖地型) 잔디에 비하여 훨씬 컸다.

• 천문학회지
• /
• 제23권1호
• /
• pp.71-82
• /
• 1990

Theoretical calculations of the combined radiative transfer and statistical equilibrium equation including the charge-particle conservations have been earned out for a multilevel hydrogen atom in quiescent prominences. Cool and dense models show the steep changes of population and radiation field in the vicinity of the surface, while these physical quantities remain unchanged for models with temperature of 7,300K, regardless of total densities. Ionization rate of hydrogen atom related with metallic line formation varies in considerable amounts from the surface to the center of model prominences cooler than 6,300K. However, such cool models cannot release enough hydrogen line emissions to explain observed intensities. Prominence models with a temperature higher than 8,000K can yield the centrally reversed Lyman line profiles confirmed by satellite EUV observations. We find that queiscent prominence with a density between $2{\times}10^{11}$ and $10^{12}cm^{-3}$ should be in temperature range between 6,300K and 8,300K, in order to explain consistently observed H alpha, beta line emissions and $n_p/n_l$ ratio.

• 한국환경과학회지
• /
• 제14권2호
• /
• pp.215-220
• /
• 2005

Thermal neutrality is not enough to achieve thermal comfort. The temperature level can be the optimal, and still people may complain. This situation is often explained by the problem of local discomfort. Local discomfort can be caused by radiant asymmetry, local air velocities, too warm and too cold floor temperature and vertical temperature difference. This temperature difference may generate thermal discomfort due to different thermal sensation in different body parts. Therefore, thermal comfort can not be correctly evaluated without considering these differences. This study investigates thermal discomfort sensations of different body parts and its effect on overall thermal sensation and comfort in air-heating room. Experimental results of evaluating thermal discomfort at different body parts in an air-heating room showed that thermal sensation on the shoulder was significantly related to the overall thermal sensation and discomfort. Although it is known that cool-head, warm-foot condition is good for comfort living, cool temperature around the head generated discomfort.

• 전기학회논문지
• /
• 제64권2호
• /
• pp.284-288
• /
• 2015

The color temperature flexibility-typed Lighting Emitting Diode(LED) lighting control system proposed in this thesis employs Pulse Width Modulation(PWM) technique to control the brightness of LED lighting. The LED lighting used as a light source has 20W downlight composed of two types of LED chips: one is Warm White and the other is Cool white. One multi-sensor module consisting an infrared sensor, an illumination sensor, and a temperature sensor was made, to which Bluetooth wireless communication technique was applied to enable a smartphone application to control lighting brightness and identify the information collected from the sensor. CS-1000, a spectroradiometer, was used to measure LED dimming control and the changing values of a color temperature in eight steps. According to a test, it was found that it was possible to change a color temperature from 3187K of Warm White LED to 5600K of Cool White LED.