• 대기
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• 제28권4호
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• pp.383-392
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• 2018

This study investigates synoptic characteristics of cold surges over South Korea during winter season (December-February). A total of 63 cold events are selected by quantile regression analysis using daily mean temperature observations from 11 KMA stations for 38 years (1979/80-2016/17). Large-scale pressure pattern during the cold surges is well characterized by high over Siberia and low over Aleutian regions, which elucidates cold advection over the Korean peninsula. However, the large-scale pattern cannot successfully explain the observed sudden decrease of temperature during the cold surges. Composite analyses reveal that a synoptic-scale cyclone developing over the northern Japan is a key feature that significantly contribute to the enhancement of cold advection by increasing pressure gradient over the Korean peninsula. Enhanced sensible and latent heat fluxes are observed over the southern ocean of Korea and Japan during the cold surges due to temperature and humidity differences between the near surface and the lower atmosphere over the ocean. The evaporated water vapor transported toward the center of the surface cyclone and condenses in the lower-to-middle troposphere. The released energy likely promotes the development of the surface cyclone by inducing positive PV near the surface of the heating region.

• 동의생리병리학회지
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• 제23권2호
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• pp.288-293
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• 2009

This study was investigated developing of Diagnosis Questionnaires which were used by Oriental Medical hospital of Dong-Eui University. We analyzed the results of Questionnaires about 620 outpatients who had participated study of diagnosis Dong-Eui University from April 2006 to March 2007. Pretest score in outcome reliability were similar on Cold, Heat, Deficiency and Excess. In Diagnosis Questionnaires, the number of variables below applied to Cold was 13, Hot was 8, Deficiency was 9, Excess was 7.

• 동의생리병리학회지
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• 제19권3호
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• pp.811-814
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• 2005

This clinical study is designed to find the characteristics of heat and cold according to Sasang Constitutions by using a statistical analysis. The study was conducted based on the questionnaire sheets and medical history (clinical data) of 1080 people registered at Sasang Constitution Information Bank (SCIB). The total number of people registered at SCIB was 1083; however, 3 Taeyangin's data were excluded in this study. The statistical analyses results on these data were: Most Taeumins have warm limbs, while Soeumins have cold ones. Taeumin, and Soyangin do not like hot weather, while Soyumin doesn't like coldness. As soeumins' body temperature is relatively lower than that of other constitutions, they tend to sleep tightly under blankets or comforters. Taeumin tend to drink more water because they sweat a lot; while Soeumin drink smaller amount of water because they sweat less. Both Taeumin, and Soyangin like cold food, but Soeumin liked hot food. Soeumin showed strong tendency for hot and cold food, while other constitutions displayed less inclination toward the certain temperature of food. Soeumin certainly had the remarkable response toward changes in heat and cold than other constitutions. The differences written above were proved to be meaningful enough by Chi-square test.

• 한국분말재료학회지
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• 제19권2호
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• pp.110-116
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• 2012

This study investigated the effects of annealing environment for the densification and purification properties of pure titanium coating layer manufactured by cold spraying. The annealing was conducted at $600^{\circ}C$/1 h and three kinds of environments of vacuum, Ar gas, and $5%H_2+Ar$ mixture gas were controlled. Cold sprayed Ti coating layer (as sprayed) represented 6.7% of porosity and 228 HV of hardness, showing elongated particle shapes (severe plastic deformation) perpendicular to injection direction. Regardless of gas environments, all thermally heat treated coating layers consisted of pure ${\alpha}$-Ti and minimal oxide. Vacuum environment during heat treatment represented superior densification properties (3.8% porosity, 156.7 HV) to those of Ar gas (5.3%, 144.5 HV) and $5%H_2+Ar$ mixture gas (5.5%, 153.1 HV). From the results of phase analysis (XRD, EPMA, SEM, EDS), it was found that the vacuum environment during heat treatment could be effective for reducing oxide contents (purification) in the Ti coating layer. The characteristic of microstructural evolution with heat treatment was found to be different at three different gas environments. The controlling method for improving densification and purification in the cold sprayed Ti coating material was also discussed.

• 설비공학논문집
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• 제20권11호
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• pp.767-774
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• 2008

This paper presented the heat transfer and pressure drop characteristics for micro plate heat exchanger with straight channel. The metal sheets for straight channel are manufactured by chemical etching and fabricated micro plate heat exchangers by using the vacuum brazing of bonding technology. The performance experiments are performed within the Reynolds numbers range of 15$\sim$250 under the same flow rate conditions for hot and cold sides. The inlet temperature of hot and cold water are conducted in the range of $30^{\circ}C{\sim}50^{\circ}C$ and $15^{\circ}C{\sim}25^{\circ}C$, respectively. Heat transfer rate and pressure drop are evaluated by the Reynolds numbers and mass flow rates as the inlet temperature variations of the hot and cold sides. Correlations of Nusselt number and friction factor are suggested for micro plate heat exchanger with straight channel using the results of performance experiment.

• 소성∙가공
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• 제12권5호
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• pp.473-478
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• 2003

This study presents the enhancement of forgeability of SNCM522H materials. Target parts are output shaft(OP shaft) used as components of power train for automobiles. To carry out cold forging process of OP shaft by 1 pass instead of existing 2 pass process, studies in terms of process design and heat treatment were performed. To introduce the new process, the finite element method was accomplished, and to assess the validity of proposed heat treatment cycle, several experiments(hardness test, observation of optical microstructures, tensile test) were carried out. The 2Pass forging process could be reduced as lPass process through improvement of process and heat treatment technology and that would give cost reduction.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2008년도 추계학술대회B
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• pp.2328-2333
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• 2008

The experimental study was carried out to evaluate the heat transfer performance on the shell side of shell-and-plate finned tube heat exchanger with three different tube numbers(9, 13 and 19). Oil flowing on the shell side was cooled by cold water flowing inside the tubes. A shell-and-tube heat exchanger of an oil cooler consisted of one shell pass and two tube passes with the inner tube diameter of 8.82 mm and the tube length of 575 mm. Mass flow rate was varied from 1.2 to $6.0\;m^3/h$ for oil and from 0.6 to $3.0\;m^3/h$ for cold water, respectively. From the experiment of shell-and-plate finned tube heat exchanger, the shell side heat transfer coefficient of heat exchanger with 9 tubes was compared with that of 13 and 19 tubes. It was found that the heat exchanger with 9 plate finned tubes showed more performance of heat transfer than that of 13 and 19 tubes.

• 대한한의학회지
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• 제18권2호
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• pp.148-154
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• 1997

In the pharmacology of traditional Korean medicine, each drug has its own specific characters. The different characters of drugs are employed to treat diseases, rectify the hyperactivity or hypoactivity of yin or yang, and help the body restore its normal physiological functions, consequently curing the diseases and restoring health. The various characters and functions of these drugs concerning medical treatment include drugs' properties, flavours, actions of lifting, lowering, floating and sinking, channel tropism, toxicity, etc. Among these theories, theory of properties and flavours of drugs provides the basis for drug analysis and application. 'Property' refers to the cold, hot, warm or cool nature of a drug. These properties of drugs are so sorted out according to the different actions of the drugs on the human body and thier therapeutic effects. Drugs which cure heat syndrome(yang syndrome) have a cold or cool property, whereas drugs which cure cold syndrome (yin syndrome) have hot or warm property Drugs of cold and cool-natured and drugs of warm and hot natures are of opposite properties. A cold-natured drug is different from a cool-natured on only in degree, and so is a warm-natured drug from a hot-natured drug. Most of the cool- or cold- natured drugs have the effects of clearing heat, purging fire, removing toxic substances, and nourishing yin, and are uese to cure heat syndromes. On the contrary, drugs of warm or hot nature usually have the effects of dispersing cold, warming up the interior, supporting yang, and treating collapse, and are therefore used to treat cold syndromes. We thought that the property of drug may be related to the autonomic nervous system in western medicine. In other words, drugs of warm or hot nature increase heart rate or acts like sympathomimetics, and drugs of cool or cold nature decrease heart rate or acts like para sympathomimetics . According to this hypothesis, we administrated some drugs to isolated rat right atrium in magnus tube. But there is no correlation between 'property' in traditional Korean medicine and autonomic nervous system in western medicine.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2004년도 추계학술대회
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• pp.1219-1224
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• 2004

The objective of this study is to propose an experimental calibration facility in which a heat flux sensor can be calibrated under conductive condition by using helium gas. The heat flux calibration facility was designed, simulated and manufactured for use in a high heat transfer condition. It delivers heat fluxes up to a maximum of 35 KW $m^{-2}$. A copper block heated electrically with 3.5 KW power is designed to produce uniform temperature up to 600 K across its face. High heat fluxes are provided between hot plate and cold plate by 1 mm height helium filled gap. A cold plate is maintained around 300 K through pool boiling using a refrigerant and water-cooled heat exchanger. A simulation was conducted to verify the design of the main test section. To verify the performance of calibration facility, a heat flux sensor was examined. The measured heat fluxes were compared to the calculated one.

• 대한치과보철학회지
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• 제31권3호
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• pp.385-393
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• 1993

Injection processing of denture base resin was introduced by Pryer in 1942, in an attempt to reduce processing shrinkage. More recently a continuous-pressure injection type technique has been developed (SR-Ivocap, Ivoclar AG, Schaan, Liechtenstein.), and it reduced processing error and increased resin density. The purpose of this study was to compare tensile bond strength of heat-cured, cold-cured, and light-cured denture base resin bonded to continuous-pressure injection type resin. To know it, 60 cylindrical resin specimens were fabricated, and tensile bond strength were measured. The results were as follows : 1. The mean tensile bond strength bonded to continuous-pressure injection type resin was lower than bonded to conventional heat cured resin. But tensile bond strength of conventional heat cured resin bonding with light cured resin was lower than continuous-pressure injection type resin. 2. Of the tensile bond strength bonded to continuous-pressure injection type resin, tensile bond strength bonding with continuous-pressure injection type resin was the greatest(but not significantly different from bonding with conventional heat cured resin), followed by cold-cured, light-cured resin. 3. Of the tensile bond strength bonded to conventional heat cured resin, tensile bond strength bonding with conventional heat cured resin was the greatest and followed by continuous-pressure injection type resin, cold-cured resin, light-cured resin. According to these results, bonding of continuous-pressure injection type resin with conventional heat cured resin or continuous-pressure injection type resin is acceptable, but bonding with light-cured resin is questionable.