• Transactions of the Korean Society of Mechanical Engineers
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• v.16 no.10
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• pp.1963-1970
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• 1992

An oscillatory motion of the natural convection in a two dimensional, partially divided square enclosure heated from below, and fitted with a partition is investigated numerically. The enclosure was composed of the lower hot and the upper cold horizontal walls and the adiabatic vertical walls, and a partition was situated perpendicularly at the mid-height of the one vertical insulated wall. The governing equations are solved by using the finite element method with Galerkin method. The computations were performed with the variation of the length and the thermal conductivity of the partition, and Rayleigh number based on the temperature difference between horizontal walls and the enclosure height with water(Pr=4.95). also, the effect of the inclination angles was studied for the transition to the oscillating flow. As the results, it was found that the intensity and frequency of oscillatory motion were affected significantly by the Rayleigh number and the length of partition. The effect of oscillatory motion was weaken with the increase of the thermal conductivity of partition. The inclination angle for the transition was raised with the increase of Rayleigh number and the length of partition.

• Journal of Energy Engineering
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• v.27 no.2
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• pp.32-48
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• 2018

Monitoring of energy use should be a priority in order to efficiently manage building energy use. Energy use in buildings can be managed by dividing them into energy sources, uses, and ZONE. By energy source, electricity, gas, fuel, and district heating are supplied to run the building's facilities. The purpose can be divided into five main applications, including cooling, heating, lighting, hot water and ventilation, but not many elevators and electric heaters that are difficult to include in the five applications are classified. ZONE Star refers to the comparison or separate management of areas for which the purpose of the building is similar or different. In addition, energy efficiency management requires control of the temperature, humidity, and people who will be measuring energy in the building, and the recent problem of fine dust should directly affect the ventilation of the building.

• Journal of the East Asian Society of Dietary Life
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• v.3 no.2
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• pp.1-13
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• 1993

This paper has examined and analyzed the ways of making Jang(Korean soybean sauce), vinegar and liquor in terms of food processes, which are mentioned in sooljip 5 and 6 Food collections of 'Kosa-sibi Jip', an encyclopaedia written in Chinese and published in 1789-the eleventh year of King Jung-jo of Chosun Dynasty. There respestively six items of nine items of and thirty three items of the recipe for making jang, vinegar and liquor, Soybean was a major material for making jang. And wheat flour and ground barley were added. Myun-jang was made from only flour. Dong-kook Jojang Bup(oriental soybean sauce preparation) which is the traditional Korean process for making jang from only soybean is recorded in this book. The cereals used in the nine items of the vinegar making recipe were rice(six times), wheat(twice), barley(three times) and wheat flour(once). And fruits are also used. Rice was most used of all these materials. The cereals used in the thirty three items of the liquor-making recipe were regular rice(50%), sticky rice(42.6%) and wheat flour(7.4%) In particular sticky rice was much used for Yakyee Rhue and Bok-sik Rhue for medications. The ways of processing cereals for liquor-making were Jee-ae-bop : steamed rice(52.9%), Jook:thick gruel with cereal (32.3%), Goo-mung Tuck: doughnut-shaped rice cake(8.8%) and Hin-moo-ree Tuck: shawith peless rice cake(2.9%). The three unique processes are as follows. First, in winter when the process of liquor-making did not go on because the jar was cold, the bottle with hot water in was put in the jar and so the aduquate temperature for liquor-making was maintained. Next, in warming up a small double boiler, they prevented effervescence by hanging down thread. Finally. in warming up in a double boiler, they sealed the mouth-piece of the jar and put a handful of wet rice when the rice was completely cooked, it was thought of as the sign that the process of liquor-making was done.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.6 no.3
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• pp.302-314
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• 1994

The effects of the inclination of enclosure and partition on natural convective flow and heat transfer were investigated numerically. The enclosure was composed of the lower hot and the upper cold horizontal walls and the adiabatic vertical walls, and a partition was positioned perpendicularly at the mid-height of one vertical insulated wall. The governing equations are solved by using the finite element method with Galerkin method. The computations were performed with the variations of the partition length and Rayleigh number based on the temperature difference between two horizontal walls and the enclosure height with water(Pr=4.95). The effects of the inclination angle of enclosure and partition on the heat transfer within an enclosure were also studied. As the results, the increase of the inclination angle of enclosure rapidly raised the heat transfer rate, while the inclination angle for the maximum Nusselt number was retarded with the increase of the partition length and the decrease of the heat transfer rate became larger in proportion to the increase of the partition length. The Nusselt number obtained by the inclination of partition was smaller than that of the inclination of enclosure. However, the difference of the heat transfer rates was considerably decreased at the longer partition lengths and the trends for the variation of the average Nusselt number were more similar with that of the inclination of enclosure. The upward oriented partition increases the convective heat transfer distinctly in contrast to that of the inclination of enclosure as the partition length increases.

• Proceedings of the SAREK Conference
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• 2009.06a
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• pp.863-868
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• 2009

The drag reduction(DR) for Betaine+Amin and Xantan Gum as kinds of surfactant and Polyacrylamide as kinds of polymer solution according to the fluid velocity, temperature and surfactant concentration were compared experimentally. For this study, two kinds of experimental apparatus for short time and long time measurement were established. Each experimental appratus was equipped with hot water storage tanks, pumps, testing pipe network, flowmeter, two pressure gauges and data logging system was built for them. Results showed that Betaine+Amin and Xanthan Gum as kinds of surfactant had appeared optimal DR around 200-500 ppm and their DR tended to be decreased when flow velocity increased but Polyacrylamide as kinds of polymer solution showed the opposite trend to be increased when flow velocity increased. The both of them showed above 40% DR in the case of better condition by the short term measurement. But Polyacrylamide as kinds of polymer solution showed more degradation than Betaine+Amin and Xanthan Gum as kinds of surfactant by the long term measurement. As a result, Betaine+Amin and Xanthan Gum as kinds of surfactant showed better materials to use to the district heating system.

• Asian-Australasian Journal of Animal Sciences
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• v.4 no.2
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• pp.131-136
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• 1991

Four male swamp buffaloes weighing $460.5{\pm}44.6kg$ were used to study the effects of different cooling techniques on draught capacity. Each animal carted an 882 kg load on the same asphalt road for one hour during four different time periods: 9:00-10:00 A.M., 10:30-11:30 A.M., 2:00-3:00 P.M. and 3:30-4:30 P.M. Simultaneously, all animals were subjected to five different treatments on five days of similar environmental conditions. In Treatment 1, animals were put stationary in a field and did no work; in Treatment 2, animals were worked without any cooling method; in Treatment 3, fifteen-minute wallow was allowed to animals prior to working; in Treatment 4, animals were covered with wetted jute bags while working, and in Treatment 5, two buckets of water were poured over the buffaloes' trunks just prior to working. The experiment was conducted from April to July 1989, when the weather was very hot. It was found that cooling methods and working times did not affect the draught efficiency of buffaloes during the one hour, but did affect physiological traits. The work load had a larger partial effect on physiological responses of buffalo other than respiration rate than did climatic variables except on the respiration rate of the buffaloes. One cooling technique that seemed to slow the increase of body temperature while working was covering the buffalo's back with wetted jute bags. Animals working at different times had significant differences in the increase of physiological traits except pulse rate.

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2017.05a
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• pp.119.2-119.2
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• 2017

무전해 니켈도금은 전기 공급 없이 환원재의 화학반응에 의해 도금이 진행되며, 복잡한 형상의 제품에도 균일한 도금 층을 형성시킬 수 있어 널리 적용되는 기술이다. 특히, 전기 니켈도금 층에 비해 무전해 니켈도금 층의 내식성과 내마모성이 우수하여 산업현장에서 가장 많이 사용되고 있다. 그러나 해양환경에서 빠른 유속 변화에 의해 발생되는 캐비테이션-침식 방지를 위한 무전해 니켈도금의 적용은 전무한 실정이다. 따라서 본 연구에서는 회주철의 캐비테이션-침식 방지를 위해 최적의 무전해 니켈도금 조건을 규명하고, 그 캐비테이션 저항성을 평가하고자 하였다. 무전해 니켈코팅을 위한 모재는 gray cast iron (FC250)을 $19.5mm{\times}19.5mm{\times}5mm$의 크기로 제작하였다. 회주철의 인장강도는 $330N/mm^2$이며, 그 성분 조성(wt.%)은 3.23 C, 1.64 Si, 0.84 Mn, 0.016 P, 0.013 S 그리고 나머지는 Fe이다. 시험편은 SiC 페이퍼 grit #1200까지 연마하였으며, 시험편의 표면 거칠기(centre line average, Ra)는 $1.6-2.1{\mu}m$ 범위 내로 제작하였다. 연마된 시험편은 증류수(distilled water) 세척 후 hot air로 건조하였다. 무전해 도금 전 시험편은 탈지를 위해 아세톤 용액(room temperature, RT)에서 3분간 초음파 세척하고, $90^{\circ}C$의 알카리 수용액으로 5분간 세척하였다. 그리고 표면활성화를 위한 산세척(acid pickling)은 5% sulfuric acid 용액에서 30초 동안 실시하였다. 무전해 Ni-P(electroless nickel, EN) 도금 전과 모든 과정마다 증류수로 시험편을 철저하게 세척하였다. EN 도금을 위한 도금욕(the bath)은 기존 문헌 연구를 통해 조성성분, 도금조건 및 변수들(the parameters)의 적절한 범위를 결정하였다. 도금조로 500mL 비커를 사용하였으며, 모든 시험편은 2시간 동안 EN deposition을 실시하였다. 캐비테이션 실험 결과 EN 도금의 표면경도가 증가함에 따라 캐비테이션 저항성도 현저하게 향상되었다.

• Economic and Environmental Geology
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• v.29 no.1
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• pp.25-33
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• 1996

Stable isotopic ratios of the carbonate rocks and chemical compositions of the matrix of pebble bearing phyllitic rocks known as the Hwanggangri Formation, which are in hot debate on their origin such as tillite, debris flow and turbidite, were determined to interpret their depositional environment. Argillaceous matrix of the pebble bearing phyllitic rocks has a high content of CaO (av. 19.5%) and MgO (av. 8.3%), corresponding to calcareous sandy shale. No difference of chemical compositions including trace elements and REE is in the matrices between the Hwanggangri and the Kunjasan Formations. Carbonate rocks from the Okchon zone and outside of the zone range $-2.5{\sim}+6.1$‰ in ${\delta}^{13}C$ and $+5.8{\sim}+25.9$‰ in ${\delta}^{18}O$, indicating normal marine limestone. However, unusally $^{13}C$ enriched carbonate rocks might be deposited in the highly evaporated sedimentary basin. A wide variation of ${\delta}^{18}O$ values is responsible for metamorphism with a $^{18}O$ depleted meteoric water. Isotopic equilibrium temperatures by graphite-calcite geothermometer show a higher metamorphic temperature ($547{\sim}589^{\circ}C$) in the Okchon zone than those ($265{\sim}292^{\circ}C$) in the Samtaesan Formation of the Chosun group. Rhythmic alternation of relatively thin shale with thin limestone in the Kounri Formation is not cherty layer but thin limesilicate bed by metasomatic replacement. Judging from the isotopic and chemical compositions of the carbonate rocks and calcareous matrix of the pebble bearing phyllitic rocks, the Hwangganari Formation was deposited in the shallow marine environment favorable to debris flow.

• The Korean Journal of Physiology and Pharmacology
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• v.14 no.5
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• pp.273-278
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• 2010

Tropical inhabitants are able to tolerate heat through permanent residence in hot and often humid tropical climates. The goal of this study was to clarify the peripheral mechanisms involved in thermal sweating pre and post exposure (heat-acclimatization over 10 days) by studying the sweating responses to acetylcholine (ACh), a primary neurotransmitter of sudomotor activity, in healthy subjects (n=12). Ten percent ACh was administered on the inner forearm skin for iontophoresis. Quantitative sudomotor axon reflex testing, after iontophoresis (2 mA for 5 min) with ACH, was performed to determine directly activated (DIR) and axon reflex-mediated (AXR) sweating during ACh iontophoresis. The sweat rate, activated sweat gland density, sweat gland output per single gland activated, as well as oral and skin temperature changes were measured. The post exposure activity had a short onset time (p<0.01), higher active sweat rate [(AXR (p<0.001) and DIR (p<0.001)], higher sweat output per gland (p<0.001) and higher transepidermal water loss (p<0.001) compared to the pre-exposure measurements. The activated sweat rate in the sudomotor activity increased the output for post-exposure compared to the pre-exposure measurements. The results suggested that post-exposure activity showed a higher active sweat gland output due to the combination of a higher AXR (DIR) sweat rate and a shorter onset time. Therefore, higher sudomotor responses to ACh receptors indicate accelerated sympathetic nerve responsiveness to ACh sensitivity by exposure to environmental conditions.

• Journal of the Korean Wood Science and Technology
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• v.44 no.4
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• pp.477-493
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• 2016

A single process using hot water (0% green liquor) and green liquor (GL) was investigated for pre-pulping extraction on two types of raw material. The GL was applied at different alkali charges of 0-5% on a dry wood weight basis. The extractions were performed at an H-factor 900 at $180^{\circ}C$. The 0% and 3% GL extraction detected acetic acid (AA) at 10.02 and $9.94g/{\ell}$, extracts derived from hardwood, 2.46 and $3.76g/{\ell}$, extracts derived from softwood, respectively. The single liquid-liquid extraction (LLE) was studied using tri-n-alkylphosphine oxide (TAPO). Response surface methodology (RSM) was employed as an efficient approach for predictive model building and optimization of AA recovery conditions. The extraction of AA was evaluated with a three-level factorial design. Three independent variables, pH (0.5-3.5), temperature ($25-65^{\circ}C$), and residence time (24-48 min) were investigated. Applying the RSM models obtained, the optimal conditions selected of extracts derived from hard- and softwood with a 3% GL were approximately pH 1.4, $26.6^{\circ}C$, 43.8 min and approximately pH 0.7, $25.2^{\circ}C$, 24.6 min, respectively. The predicted and experimental values of AA recovery yield were similar whilst sugar retention was 100%.