• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.30 no.4
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• pp.175-185
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• 2018

This research investigates the internal flow and heat transfer in a plate heat exchanger with chevron shape by utilizing the computational fluid dynamics (CFD) software. The basic unit of the plate heat exchanger is generally composed of a hot channel, an intermediate chevron plate, and a cold channel. Several studies have reported experimental and numerical simulation of heat transfer and pressure drop. This study focused on the detailed numerical simulation of flow and heat transfer in the complicated chevron shape channel. The long chevron plate was designed to include 16 chevron patterns. For proper mesh resolution, the number of cells was determined after the grid sensitivity test. The working fluid is water, and its properties are defined as a function of temperature. The Reynolds number ranges from 900 to 9,000 in the simulation. A realizable $k-{\varepsilon}$ model and non-equilibrium wall function are properly considered for the turbulent flow. The friction factors and heat transfer coefficient are validated by comparing them with existing empirical correlations, and other patterned flow phenomena are also investigated.

• Journal of Environmental Science International
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• v.16 no.12
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• pp.1337-1343
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• 2007

The aim of this study was to isolate chicken feather-degrading bacteria with high keratinolytic activity and to investigate cultural conditions affecting keratinolytic enzyme production by a selected isolate. A chicken feather-degrading bacterial strain CH3 was isolated from poultry wastes. Isolate CH3 degraded whole chicken feather completely within 3 days. On the basis of phenotypical and 16S rDNA studies, isolate CH3 was identified as Bacillus thuringiensis CH3. This strain is the first B. thuringiensis described as a feather degrader. The bacterium grew with an optimum at pH 8.0 and $37^{\circ}C$, where maximum keratinolytic activity was also observed. The composition of optimal medium for keratinolytic enzyme production was feather 0.1%, sucrose 0.7%, casein 0.3%, $K_2HPO_4$ 0.03%, $KH_2PO_4$ 0.04%, $MgCl_2$ 0.01% and NaCl 0.05%, respectively. The keratinolytic enzyme had a pH and temperature optima 9.0 and $45^{\circ}C$, respectively. The keratinolytic activity was inhibited ethylenediaminetetraacetic acid, phenylmethylsulfonyl fluoride, and metal ions like $Hg^{2+},\;Cu^{2+}\;and\;Zn^{2+}$. The enzyme activated by $Fe^{2+}$, dithiothreitol and 2-mercaptoethanol.

• The Journal of Internal Korean Medicine
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• v.25 no.3
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• pp.633-639
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• 2004

A varicose vein of the lower limbs is dilated, tortuous and elongated vein. Western medical treatment involves conservative management, sclerotherapy, and surgery. Currently, internal medicinal treatment is inadequate. Recently a patient was diagnosed with varicose veins of the lower limbs based on clinical symptoms. In this case, Guibi-tang was administered and clinical symptoms improved. This report suggests that oriental medicinal treatment is efficacious in treating varicose veins of the lower limbs. We think that further oriental medical studies on various surgical diseases are needed.

• Journal of Physiology & Pathology in Korean Medicine
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• v.23 no.5
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• pp.964-968
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• 2009

The purpose of this study is to select the major pulse indicators and evaluate their significance in discriminating the subtypes of Pattern Identifications (PI) from stroke patients. Decision tree analysis was carried out using clinical data collected from 835 stroke patients with the same subtypes diagnosed identically by two experts with more than 3 year clinical experiences. Among the 10 pulse indicators, 6 major pulse indicators (slow, rapid, strong, weak, slippery, and fine pulse) were selected by decision tree analysis. The accumulated distributions of six pulse indicators in each PI showed that strong was major pulse indicator in Fire-Heat pattern, slippery in Dampness Phlegm pattern, weak in Qi Deficiency pattern. But there were two major combinations in Yin deficiency pattern, weak or fine with rapid pulse and weak or fine without rapid pulse. Therefore, it is suggested that 6 pulse indicators can be used for discrimination of PI in stroke patients, though the combination studies between these pulse indicators and the other PI indicators are left for further study.

• Journal of Physiology & Pathology in Korean Medicine
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• v.23 no.2
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• pp.499-504
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• 2009

The purpose of this study was to evaluate the diagnostic indicators which are used for the identification of fire-heat pattern in stroke patients. For evaluation of diagnostic indicator, we analyzed the indicators which are composed of symptoms and signs collected from stroke patients based on the clinical records using case report form (CRF). Patients had a first-ever stroke within 1 month after the onset of stroke. Pattern identification was performed and decided by two independent physicians. Two patient groups that consist of fire-heat pattern and the other patterns were compared to isolate important indicators affecting the fire-heat pattern identification of stroke patients. The 8 indicators among 16 fire-heat pattern indicators were significantly more frequent compared with non fire-heat pattern group. Logistic regression analysis revealed that 5 indicators among fire-heat indicators were significantly sensitive indicators being capable of identification of fire-heat pattern. But two of them was from the indicators of dampness-phlegm pattern and yin deficiency pattern. Therefore, further studies are required for the development of Korean standard indicators of Fire-heat pattern identification.

• Journal of the Korean Society for Heat Treatment
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• v.18 no.2
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• pp.99-104
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• 2005

In this study, the effects of C and Si on damping capacity and mechanical properties of as-cast and as-rolled Fe-17%Mn alloys were investigated as a basic study for the purpose of the commercialization of the alloy. The $M_s$ temperature of ${\gamma}{\rightarrow}{\varepsilon}$ martensitic transformation in Fe-17%Mn alloy was decreased with increasing C and Si contents, resulting in the less volume fraction of ${\varepsilon}$ martensite. The damping capacity was also decreased with increasing alloying content because of less ${\varepsilon}$ amount and the reduction in mobility of the damping sources such as the stacking fault boundaries and ${\gamma}/{\varepsilon}$ interfaces due to the pinning effect by alloying elements. The mechanical properties of as-rolled alloys were superior to those of as-cast alloys probably because of finer ${\gamma}$ grains, larger amount of ${\varepsilon}$ martensite, and chemical homogeneity.

• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.3 no.2
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• pp.166-176
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• 1993

In order to investingate the renal dysfunction in workers exposed to aromatic organic solvents, 105 male exposed workers and 109 controls were participated in this study. This study was conducted to examine the correlation among the concentration of aromatic organic solvents in air, worker's urinary NAG activity and urinary hippuric acid. The results were as follows : 1. The exposure level of aromatic organic solvent mixture caculated by the equation proposed by ACGIH was ranged from 0.27 to 0.54 and toluene concentration was ranged from 18.3ppm to 48.3ppm. 2. NAG activity in the urine of control and exposed group were $36.1{\pm}14.2nmolMU/mg$ creatinine and $52.4{\pm}26.1nmolMU/mg$ creatinine, respectively. Hippuric acid concentration in the urine of control and exposed group were $191.1{\pm}194.2mg/g$ creatinine and $789.3{\pm}784.1mg/g$ creatinine, respectively. 3. Correlation coefficent between the exposure level of aromatic organic solvent mixture was significantly related to urinary NAG activity(r=0.542) and urinary hippuric acid(r=0.752). 4. Correlation coefficient between NAG activity and hippuric acid concentration was 0.357. This study suggested that urinary NAG activity was a good renal function index for aromatic organic solvents exposure and urinary hippuric acid was an index for the biological monitoring of toluene exposure.

• Journal of Yeungnam Medical Science
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• v.8 no.2
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• pp.202-208
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• 1991

Hand injury in children was increased due to multiple environmental risks and failed attention of parents to children in rapidly developing society. By the results of this evaluation in 37 cases, it was summarized as follows. First, hand injuries in children most commonly occurs in spring, and occurs more commonly in the children at the age of high activity. The most common level of injury is zone I by microreplantation zone, and zone II by tendon injury zone. The more desirable results were obtained by full thickness skin graft and composite graft if it were possible. For the better functional results compare to adults, the methods and procedures must be constructed after more evaluation with more clinical cases. In the cases of pediatric hand injury, the most important fact is prevention of injury, with the close attention by parents, and the second is appropriate diganosis and treatment for more functional results.

• Journal of Korea Foundry Society
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• v.25 no.2
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• pp.73-79
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• 2005

Effects of Cr and Ni addition on damping capacity, mechanical property, and corrosion resistance of Fe-17%Mn martensitic alloy have been studied. Martensite start temperature($M_{S}$) of the alloy decreases linearly with increasing Cr and Ni contents up to 15%. The damping capacity decreases gradually from 27 to 22% in specific damping capacity(SDC) with increasing Cr and Ni contents from zero to 10%, and decreases rapidly with further Cr and Ni content in Fe-17%Mn alloy. The tensile strength of the alloy maintains a level of 60 $kgf/mm^{2}$ regardless of Cr content with an elongation of 20 to 25%. But, in case of Fe-17%Mn-x%Ni alloy, the tensile strength decreased rapidly with the Ni content of above 10% because of austenite morphology. Immersion test in 5% NaCl solution leads to the result that the corrosion resistance of the alloy becomes excellent above 10% Cr. From the above results, it is concluded that the optimum Cr content to improve the mechanical property and corrosion resistance of the alloy in 5%NaCl solution with a lesser decrease in damping capacity is about 10%. In the case of 5% $H_{2}SO_{4}$ condition, the Fe-17%Mn-10%Ni is an optimum alloy.

• Journal of Korean Society for Atmospheric Environment
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• v.4 no.1
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• pp.79-83
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• 1988

To improve working environment for the toll workers who were working at Kyungbu expressway in outskirts of Seoul and Suwon, the status of air pollution surrounding toll booth were measured from March 28 through June 14, 1986. The results were as follows: 1. The amount of TSP (total suspended particle) surrounding toll booth was directly proportional to the traffic load. The ratio of traffic load at Seoul and Suwon toll was 3.2:1 and of TSP was 2.6:1. 2. The proportion of particle larger than 5$\mum$ was 24.8 $\sim$ 34.9% of TSP at Seoul toll and 19.2 $\sim$ 32.7% at Suwon. The proportion of particle less than 2$\mum$ was 38.7 $\sim$ 51.8% of TSP at Seoul toll and 34.8 $\sim$ 54.8% at Suwon. 3. The concentration of respirable particle les than 7$\mum$ measured by personal air sampler was higher in Seoul toll booth than that of Suwon and it seems to be influenced by the exhausion of diesel engine. Especially the concentration of respirable particle of reformed toll booth with air curtain was 20% lower than unreformed one. 4. Concentration of Pb among suspended particles around Seoul toll was 5 times higher than Pb of Suwon toll. So it is considered that there were other possible pollution source of Pb beyond heavy traffic in Seoul toll area. The amount of Pb inside toll booth was extremely small but the concentration of benzo(a)pyrene showed a trend of increase according to traffic stagnation. 5. The concentration of $SO_2$ arround toll showed no difference between weekday and weekend and also showed no relation with traffic load. But the concentration of $NO_2$ was affected by traffic load.