• 대한기계학회논문집A
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• 제34권12호
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• pp.1829-1836
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• 2010

지역난방은 열병합 발전소에서 생산된 열을 온수의 형태로 열배관 네트워크를 통해 넓은 지역에 일괄적으로 공급하는 난방시스템이다. 일반적으로 지역난방 열배관은 지중에 매설되며 내부를 흐르는 온수의 압력과 온도변화, 매설 토사와의 마찰 및 반력에 의한 하중을 받게 되므로 열공급 효율과 함께 기계적인 안전성에 대한 검토가 반드시 필요하다. 본 논문에서는 강관의 한계상태 설계법을 이용하여 한계판폭두께비와 한계변형률, 두 가지 관점에서 열배관의 국부좌굴 발생여부를 평가하였으며 그 결과 현재 국내에서 사용되고 있는 모든 열배관은 국부좌굴이 발생하지 않음을 확인하였다. 마지막으로 국부좌굴을 피하기 위한 최소 예열온도를 산출함으로써 예열온도에 대한 시공 기준을 제시하였다.

• 대한기계학회논문집
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• 제12권4호
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• pp.847-864
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• 1988

본 연구에서는 연료분출에 박리가 있는 경우와 없는 경우 각각에 대하여 화염 대 근처의 국부가속 현상이 박리에 의하여 어떻게 영향을 받는가를 실험적으로 규명하 고, 나아가서 종래에 행해져 왔던 관련 연구 결과를 재검토할려고 한다.

• 대기
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• 제26권3호
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• pp.445-459
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• 2016

Air temperature deviation (ATD) is one of major indicators to represent spatial distribution of urban heat island (UHI), which is induced from the urbanization. The purpose of this study is to evaluate the accuracy of air temperature deviation about Climate Analysis Seoul (CAS) workbench, which had developed by National Institute Meteorological Science and TU Berlin. Comparison and correlation analysis for CAS ATD including meso-scale air temperature deviation, local-scale air temperature deviation, total air temperature deviation, surface heat flux deviation, cold air production deviation among meso-scale numerical modelling variable in 'Seoul Region', micro-scale numerical modelling in 'Detail Region', and CAS workbench variable using observation data in ground stations. Comparison between night time OBS ATD and CAS ATD show that have most close values. Most of observations ($dT_{max}$ and $dT_{min}$) have highly positive ($dT_{SHP}$, $dT_{CA}$, MD, TD, $f_{BS}$, $f_{US}$, $f_{WS}$, $h_B$) and negative ($f_{VS}$, $f_{TV}$, $h_V$, Z) correlations. However, CAS workbench needs further improvement of both observational framework and analytical framework to resolve the problems; (1) night time OBS ATD of has closer values in compare with at high rise mountain area and (2) correlations are very dependable to meteorological scale.

• 한국지역사회생활과학회지
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• 제15권2호
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• pp.55-64
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• 2004

The purpose of this study was to examine the differences in skin temperature and thermal comfort of participants in a $19^\circ{C}$ room (the recommended room temperature in the winter) depending on age, sex and clothing weight. Subjects were divided into four groups (6 young males, 5 young females, 6 old males, 6 old females) and experimental trials consisted of three conditions: wearing underwear in a $19^\circ{C}$ room (19CUW), without underwear in a $19^\circ{C}$ room (19C), and without underwear in a $24^\circ{C}$ room (24C). The results indicated the following: 1) There were no significant differences in mean skin temperature based on age or sex, and the mean skin temperatures of the four groups were in the range of 32.4∼$34.0^\circ{C}$. 2) In the 19C condition, the skin temperatures of the hands and feet of old females were higher than those of the other three groups. 3) In terms of perceived thermal comfort, young females showed a tendency to feel the most uncomfortable. Both old and young groups agreed that the 24C condition was the most comfortable. 4) Relational coefficients between thermal comfort and skin temperatures were higher in the young group than in the old group. Furthermore, the perceived thermal comfort had a stronger relationship with mean skin temperatures than with local skin temperatures. 5) The mean skin temperatures of subjects who indicated they were 'comfortable' were in the range of 31∼$36^\circ{C}$ regardless of age or sex.

• 한국축산식품학회지
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• 제18권4호
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• pp.322-331
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• 1998

Good temperature control in the chill chain is imperative for maintaining safety and quality of the fresh meat. Therefore, the actual state of temperature or relative humidity histories of fresh meat product from carcass chill room to retail shop and the temperatures of chill and freezing rooms at local butcher shops were monitored by means of data loggers. The relative humidity and air temperature in carcass chill room were between 86 and 98%, and -3 and 0$^{\circ}C$, respectively. The surface temperatures of boxed beef measured in winter, when the outside air temperature was measured between -2 and -5$^{\circ}C$, were recorded between 1 and 3$^{\circ}C$, although transport vehicle switched off the chilling unit during transportation, However, the inside temperatures of chill transport vehicle measured in summer, when the transport time was prolonged to maximum 8 hrs, were raised to 10 to 15$^{\circ}C$, in worst case up to 25$^{\circ}C$. In that case, however, the inside temperature of boxed beef was maintained generally lower than 5$^{circ}C$ as the loading and unloading were finished within 30 min. The storage temperatures for meat in the subfreezing room, at which the butcher shops in local market are used to set to facilitate the thin slicing of meat, were measured between -2 and -8$^{\circ}C$. Furthermore, the temperatures of storage room for vacuum packaged meat in the chilled meat retail shops were maintained generally between 0 and +2$^{\circ}C$.

• 대한기계학회논문집
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• 제13권5호
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• pp.1012-1022
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• 1989

본 연구에서는 열원인 내관의 온도가 불균일한 경사진 동심환상공간에서의 열전달 특성을 $R_{a}$ =3*$10^{4T,P}$1r=7.0, 내외관의 반경비 0.6일 때 경사각도 0。,30。그리고 60。에 대하여 3차원 수치해석으로 연구하였으며 균일온도분포인 경우 와 비교 고찰하였다.

• 한국정보통신학회:학술대회논문집
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• 한국정보통신학회 2022년도 춘계학술대회
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• pp.89-91
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• 2022

실내에서 측위를 위해 주로 사용되는 무선 센서 네트워크(WSN)는 수신 신호 강도(RSSI)의 정확성에 의존한다. 이 RSSI는 간섭을 유발하는 여러 요인에 민감하며, 그 중 온도가 실내/외 환경에서 RSSI에 큰 영향을 미친다는 국외 연구 사례가 있다. 실내에서는 열원이나 공조 시스템으로 인해 실내 공간의 온도가 고르지 않으며, 특정 위치에서는 잦은 온도 변화가 발생한다. 특히, 실내 화재 상황 시 대피 경로 안내를 위해 정확한 측위 시스템이 요구되지만 Receiver 주변에서의 화재로 인해 국부적으로 높은 온도가 형성되어 RSSI 값에 영향을 미칠 수 있다. 본 논문에서는 SoC 내부 및 국부 온도와 RSSI의 상관관계 분석을 통해 RSSI에 미치는 영향을 연구하고자 한다.

• Structural Engineering and Mechanics
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• 제66권4호
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• pp.477-485
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• 2018

This study aims to investigate the influence of individual and hybrid fiber on the local bond-slip behavior of medium and high strength concrete after exposure to different high temperatures. Tests were conducted on local pullout specimens (150 mm cubes) with a reinforcing bar embedded in the center section. The embedment lengths in the pullout specimens were three times the bar diameter. The parameters investigated include concrete type (control group: ordinary concrete; experimental group: fiber concrete), concrete strength, fiber type and targeted temperature. The test results showed that the ultimate bond stress in the local bond stress versus slip curve of the high strength fiber reinforced concrete was higher than that of the medium strength fiber reinforced concrete. In addition, the use of hybrid combinations of steel fiber and polypropylene fiber can enhance the residual bond strength ratio of high strength concrete.

• 한국결정학회지
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• 제12권2호
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• pp.81-87
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• 2001

We have studied the effect of sintering temperature and time on the cation ordering and second phase formation in Ba(Mg/sub 1/3/Nb/sub 2/3/)O₃(BMN) microwave ceramics by using transmission electron microscopy. The relationship between the structural-chemical behavior arid microwave dielectric properties has also been investigated. It is revealed that according to the sintering conditions the BMN ceramics show very diverse local ordering behavior, such as the development of domain twinning and "core-shell"-structured grains and the formation of local disordered domains, though having 1 : 2 cation ordering structure basically. The disordered structure is found in Mg-excess region. Such local chemical variation seems to be caused by the formation of BaNb₂O/sub 6/-like second phase in its neigh-boring grain boundary. The microwave dielectric quality factor of the ceramics decreases greatly with the increase of the structural-chemical inhomogeneity and diversity.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2000년도 추계학술대회논문집B
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• pp.267-271
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• 2000

The local heat transfer rate of an axisymmetric submerged air jet impinging on normal to a heated flat plate was investigated experimentally with varying solidity of mesh screen. The mean velocity and turbulent Intensity profiles of streamwise velocity component were measured using a hot-wire anemometry. The temperature distribution on the heated flat surface was measured with thermocouples. The screen installed in front of the nozzle exit(behind of 35mm) modify the jet flow structure and local heat transfer characteristics. For higher solidity screen, turbulence intensity at core lesion is high and increases the local heat transfer rate at nozzle-to-plate spacings(L/D<6). For larger nozzle-to-plate spacings(L/D>6), however, the turbulent Intensities of all screens tested in this study approach to an asymptotic curve, but the small mean velocity at the core region reduces the local heat transfer rate for high solidity screens.