• 설비공학논문집
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• 제26권1호
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• pp.8-14
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• 2014

We have performed experiments to enhance the stratification in a storage tank in order to raise the collector efficiency and solar fraction in solar thermal systems. The storage tank with a spiral jacket in the side wall has a scroll-shaped heat exchanger coil added to the upper part. The performance was compared between only the side and upper-side heating part through simulation using TRNSYS under the same weather conditions and initial conditions. As a result, the upper-side heating has a 4.2% advantage in solar fraction, but almost no increase in collector efficiency.

• 한국연초학회지
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• 제16권2호
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• pp.122-127
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• 1994

Feeding preference of cigarette beetle, Lasioderma sewicorne F., on cured tobacco leaves was investigated to obtain basic information on ecological management of the insect pest in tobacco storage warehouses. About 3, 000-4, 000 adults of the insect were released in a warehouse in which groud tobacco leaves were placed on the bottom and at 3m above the floor level, and numbers of insects attracted were examined. There was no significant difference on feeding preference between the two tobacco varieties, flue-cured(NC82) and air-cured(Br3l) tobacco leaves. However, significant differences were noted in feeding preference between thick and thin leaves and among different quality grades within a tobacco variety. Feeding preferences of cigarette beetle between flue- and air- cured tobacco varieties showed significant differences on the lower position, though there were no differences on the 3m upper position. On the 3m upper position, feeding preferences were different between thick and thin leaves of tobacco varieties, and variety X thickness and variety X thickness equality grades showed statistically significant differences. Significantly higher feeding preference by cigarette beetle adults was observed for the food placed on the 3m upper than on the lower position. There were negative correlations between quality grades of cured tobacco leaves and feeding preference on the lower position, and the regression equation was Y(feeding preference)=4.050-0.683 X (degree).

• 대기
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• 제22권3호
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• pp.321-330
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• 2012

Generation mechanisms of the three moderate-or-greater (MOG)-level clear-air turbulence (CAT) encounters over South Korea are investigated using the Weather Research and Forecasting (WRF) model. The cases are selected among the MOG-level CAT events occurred in Korea during 2002-2008 that are categorized into three different generation mechanisms (upper-level front and jet stream, anticyclonic flow, and mountain waves) in the previous study by Min et al. For the case at 0127 UTC 18 Jun 2003, strong vertical wind shear (0.025 $s^{-1}$) generates shearing instabilities below the enhanced upper-level jet core of the maximum wind speed exceeding 50 m $s^{-1}$, and it induces turbulence near the observed CAT event over mid Korea. For the case at 2330 UTC 22 Nov 2006, areas of the inertia instability represented by the negative absolute vorticity are formed in the anticyclonically sheared side of the jet stream, and turbulence is activated near the observed CAT event over southwest of Korea. For the case at 0450 UTC 16 Feb 2003, vertically propagating mountain waves locally trigger shearing instability (Ri < 0.25) near the area where the background Richardson number is sufficiently small (0.25 < Ri < 1), and it induces turbulence near the observed CAT over the Eastern mountainous region of South Korea.

• 한국환경과학회지
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• 제16권10호
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• pp.1127-1137
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• 2007

We focused on effects on data assimilation of simulated wind fields by using upper-air observations (wind profiler and sonde data). Local Analysis Prediction System (LAPS), a type of data assimilation system, was used for wind field modeling. Five cases of simulation experiments for sensitivity analysis were performed: which are EXP0) non data assimilation, EXP1) surface data, EXP2) surface data and sonde data, EXP3) surface data and wind profiler data, EXP4) surface data, sonde data and wind profiler data. These were compared with observation data. The result showed that the effects of data assimilation with wind profiler data were found to be greater than sonde data. The delicate wind fields in complex coastal area were simulated well in EXP3. EXP3 and EXP4 using wind profiler data with vertically high resolution represented well sophisticated differences of wind speed compared with EXP1 and EXP2, this is because the effects of wind profiler data assimilation were sensitively adjusted to first guess field than those of sonde observations.

• Journal of Mechanical Science and Technology
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• 제15권4호
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• pp.492-499
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• 2001

The characteristics of Prand시-Meyer expansion of supersonic flow with condensation along a wavy wall in a channel are investigated by means of experiments and numerical analyses. Experiments are carried out for the case of moist air flow in an intermittent indraft supersonic wind tunnel. The flow fields are visualized by a Schlieren system and the distributions of static pressure along the upper wavy wall are measured by a scanning valve system with pressure transducers. In numerical analyses, the distributions of streamlines, Mach lines, iso-pressure lines, and iso-mass fractions of liquid are obtained by the two-dimensional direct marching method of characteristics. The effects of stagnation temperature, absolute humidity, and attack angle of the upper wavy wall on the generation and the locations of generation and reflection of an oblique shock wave are clarified. Futhermore, it is confirmed that the wavy wall plays an important role in the generation of an oblique shock wave and that the effect of condensation on the flow fields is apparent.

• International Journal of Safety
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• 제2권1호
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• pp.34-38
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• 2003

The lower and upper flash points of the flammable binary system, butylacetate+2-propanol were measured by air blowing tester. The shape of the concentration-temperature region of flash depended on the components of the mixture in solution. The experimental data were compared with the values calculated by the reduced model under an ideal solution assumption and the flash point-prediction models based on Van Laar equation. Good qualitative agreement was obtained with these models. The prediction results of these models can thus be applied to incorporate inherently safer design for chemical process, such as the determination of the safe storage conditions for flammable solutions.

• 한국대기환경학회지
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• 제13권2호
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• pp.103-113
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• 1997

The research described in this paper was conducted to estimate the stability and heat budget in planetary boundary layer (PBL) at Kimhae. The upper air observation was carried out during period from 3 Februsry 1993 to 5 February 1993 at Kimhae. The surface observation data used the one during period from 1 April 1994 to 31 March 1995. The maximum height of inversion layer observed at Kimhae was 310 m. Destruction of the inversion was simultaneously occurred at the surface and the mid-layer (200 $\sim$ 300 m), however the origin of destruction is different each other. The surface inversion is destructed by surface heating owing to growing radiation in surface but disappearance of the mid-layer inversion is related to the upper cold air movement.

• 제어로봇시스템학회논문지
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• 제16권10호
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• pp.919-926
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• 2010

This paper proposes a wearable hand rehabilitation device, DULEX, for persons with functional paralysis of upper-limbs after stoke. DULEX has three degrees of freedom for rehabilitation exercises for wrist and fingers except the thumb. The main function of DULEX is to extend the range of motions of finger and wrist being contracture. DULEX is designed by using a parallel mechanism, and its parameters such as length and location of links are determined by kinematic analysis. The motion trajectory of the designed DULEX is aligned to human hand to prevent a slip. To reduce total weight of DULEX, artificial air muscles are used for actuating each joint motion. In feedback control, each joint angle is indirectly estimated from the relations of the input air pressure and the output muscle length. Experimental results show that DULEX is feasible in hand rehabilitation for stroke survivals.

• 설비공학논문집
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• 제16권10호
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• pp.984-989
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• 2004

Significant air temperature increases in urban areas is well known as the heat island phenomenon in a global scale. Therefore, we propose numerical model in order to analyze quantitative effects of building environmental factors on the heat island phenomenon in urban area. In this paper, thermal property of upper atmosphere is experimentally investigated for Sakae, Nagoya Japan. In conclusion, it was confirmed that the boundary layer of a urban canopy existed near the altitude of 139 m.

• 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.