• Proceedings of the Korea Water Resources Association Conference
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• 2015.05a
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• pp.559-559
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• 2015

하천은 크게 이수와 치수 및 환경 등의 주요 기능을 가지고 있다. 이수는 하천과 물이 주는 가치를 말하며, 치수는 기능이라기 보다는 엄밀한 의미에서 하천관리를 통한 자연재해 방지를 의미한다. 이러한 이 치수 기능의 확보와 수변환경 조성을 위해 친환경적 수리구조물인 가동보의 설치가 증가 하고 있다. 가동보는 하천에 주로 설치되는 수리구조물 중의 하나로 국내에서는 2000년 대부터 고정보를 대신하여 설치가 시작 되었으며, 최근 친환경적 하천정비 및 다양한 목적 등으로 국내 하천에 약 1,200여개의 가동보가 설치 및 운영되고 있다. 이와 같이 다목적 활용을 위해 가동보의 수요가 급증하고 있으나, 안전한 이 치수를 위한 유량 계측 시스템은 국내 외 적으로 구축되어 있지 않은 실정이다. 하천 유량 자료는 하천관리에 있어 서 필수적인 요소이며, 하천 유량 측정을 위해 국토교통부 및 환경부에서는 매년 막대한 예산을 사용하고 있는 실정이다. 이에, 본 연구에서는 단면이 일정한 가동보 특징을 고려하여 높이 측정센서와 상류측 수위 측정 센서로부터 계측된 자료를 추출하여 가동보 월류량 산정식을 적용해 가동보와 연계한 실시간 유량 계측 시스템을 개발하였다. 개발 결과 각 센서의 계측값을 이용하여 실시간 하천유량 계측이 가능하며, 기 설치된 가동보에 적용이 가능해 개발된 기술을 국내 가동보에 적용한다면 정량적인 실시간 유량 측정이 가능하여 안전한 하천관리가 가능할 것으로 판단된다.

• Journal of the Korean Society of Propulsion Engineers
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• v.13 no.2
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• pp.26-34
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• 2009

Secondary flow losses can be as high as 30~50% of the total aerodynamic losses for a turbo-machinery blade or stator row. These are important part for improving a turbine efficiency. Therefore, many studies have been performed to decrease the secondary flow losses. The present study deals with the chamfered leading-edge at a generic wing-body junction to decrease the horseshoe vortex, one of factors to generate the secondary flow losses, and investigates the vortex generation and the characteristics of the horseshoe vortex with the chamfered height, and depth of the chamfer by using $FLUENT^{TM}$. It was found that the total pressure loss for the best case can be decreased about 1.55% compare to the baseline case.

• The Journal of the Acoustical Society of Korea
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• v.40 no.2
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• pp.155-160
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• 2021

This paper proposes an automatic method for detecting snore sound, one of the important symptoms of sleep apnea patients. In the proposed method, sound signals generated during sleep are input to detect a sound generation section, and a spectrogram transformed from the detected sound section is applied to a classifier based on a Convolutional Bidirectional Gated Recurrent Unit (CBGRU) with attention mechanism. The applied attention mechanism improved the snoring sound detection performance by extending the CBGRU model to learn discriminative feature representation for the snoring detection. The experimental results show that the proposed snoring detection method improves the accuracy by approximately 3.1 % ~ 5.5 % than existing method.

• Resources Recycling
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• v.30 no.1
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• pp.26-34
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• 2021

Titanium is the fourth most abundant structural metal, after aluminum, iron, and magnesium. However, it is classified as a 'rare metals', because it is difficult to smelt. In particular, the primary titanium production process is highly energy-intensive. Recycling titanium scraps to produce ingots can reduce energy consumption and CO2 emissions by approximately 95 %. However, the amount of metal recycled from scrap remains limited of the difficulty in removing impurities such as iron and oxygen from the scrap. Generally, high-grade titanium and its alloy scraps are recycled by dilution with a virgin titanium sponge during the remelting process. Low-grade titanium scrap is recycled to ferrotitanium (cascade recycling). This paper provides an overview of titanium production and recycling processes.

• Journal of Korean Medical classics
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• v.35 no.4
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• pp.115-125
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• 2022

Objectives : This study reviews whether the traditional medical thought process reflected in the Traditional Chinese Medical Treatment Plan for COVID-19 is based on existing classical texts, and examine concerns over the quality of evidence that the plan is based on. Methods : First, terminology and basic formulas composing the compound formulas in the COVID-19 TCM Treatment Plan were collected. Next, their usage in existing classical texts were searched in the medical classics database. Results : Infectious diseases similar to COVID-19 were understood as external disease due to Six Qi in the texts. Basic formulas used for treatment were those applied in Shanghan and Wenbing, among which cases where such formulas were applied in infectious diseases could be found in the classics. Conclusions : The level of evidence of the Treatment Plan suggested by various specialists could be evaluated as insufficient if we consider the literature. However, if application of such a plan could be supported institutionally, it could become a starting point for evidence generation.

• Clean Technology
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• v.18 no.2
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• pp.200-208
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• 2012

This study was performed to prevent the health damage of environmental contaminants in Industrial Complex Area. And, this study aimed to identify the concentration levels and distribution characteristics of environmental contaminants and Polycyclic Aromatic Hydrocarbons (PAHs) at soil in Industrial Complex Area and control area. The concentration of the soil pollution standard such as the heavy metals in the soil, VOCs, PAHs, and PCB were measured and analyzed using the soil specimens in the Industrial Complex Area and control area. Soil specimens from the Industrial Complex Area (the direct exposure area) and the control area were surveyed. Songdo-dong, Haedo-dong and Jechul-dong, which are in the direct exposure area and near the emission source, showed relatively high concentrations of contaminant materials when compared with Jangki-myeon, which is far off and in the control area. The concentration of zinc was 20.8-58.9% of the level of concern (300 mg/kg) in the 1st region, which is a relatively high concentration. The concentration of fluoride was under the standard in every region, but it was about 74% of the level of concern (400 mg/kg) in the 1st region. It is recommended that controlling fluoride emissions is necessary. Levels of organic phosphate, phenol, and VOCs like benzene, toluene, ethylbenzene and xylene were under the detection limit of the analysis instruments. The concentration of TPH was high in Songdo-dong. The concentration of contaminants in Jechul-dong was high. In addition, it was observed that the level of soil contamination changed depending on the distance from the emission source. The concentration of PAH compounds in the soil was 18.71-1744.59 ng/g, and the concentration of six potential cancer-causing PAH materials was 6.54-695.94 ng/g. The highest concentration was in Songdo-dong. The PAH concentration in the direct exposure area near the complex was relatively high compared to the indirect exposure area.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.31 no.3
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• pp.399-408
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• 1998

The effect of low molecular alginates feeding on the cholesterol levels and fatty acid compositions of rat serum and liver lipid were investigated. After one week basal diet feeding, four week old Sprague-Dawley male rats were fed with water soluble and acid $\cdot$alkali soluble alginate extracted from sea mustard (Undaria pinnatifida) and giant kelp (Macrocystis pyrifera), and their low molecular alginates prepared by the HCl partial hydrolysis. The feeding efficiency of the alginate fed group was ranged in 0.37$\~$0.44, which was 0.03$\~$0.05 lower than that of the basal diet group. Also, there was much less increase of liver weight in the alginate fed group. The water soluble alginate showed more significant effect in reducing the total cholesterol, free cholesterol, LDL-cholesterol, triglyceride and phospholipid of serum and liver lipid than the acid$\cdot$alkali soluble alginate. The effect was much better with low molecular alginate (reducing effect by the low-molecularization : Water soluble alginate - serum lipid; total cholesterol $59\%$, free cholesterol $65\%$, LDL-cholesterol $96\%$, triglyceride $50\%$, and phospholipid $36\%$. liver lipid: total cholesterol $4\%$, free cholesterol $62\%$, LDL-cholesterol $44\%$, triglyceride $33\%$, and phospholipid $44\%$. acid$\cdot$alkali soluble alginate - serum lipid; total cholesterol $52\%$: free cholesterol $97\%$, LDL-cholesterol $78\%$ triglyceride $32\%$, and phospholipid $64\%$. liver lipid; total cholesterol $11\%$, free cholesterol $12\%$, LDL-cholesterol $10\%$, triglyceride $27\%$, and phospholipid $21\%$). The effect of low molecular alginate feeding on the fatty acid composition of serum and liver lipid reflects the remarkable increase of polyenoic acid, over $44\%$ in serum lipid and about $70\%$ in liver lipid, comparing to the cholesterol fed group. The overall results indicated that feeding of low molecular alginates improves physiological function of rats by changing the serum and liver lipid composition.

• Journal of Korean Ophthalmic Optics Society
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• v.7 no.2
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• pp.33-39
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• 2002

The purpose of this study is to evaluate the effects of continuing work on VDT(video display terminal). Therefore, we examined visual fatigue by a questionnaire and measured frequency of blinking, tear film break-up time(BUT), height of palpebral fissure, visual acuity, refraction with retinoscopy and accommodation before and after two hour long VDT work. For the ocular symptoms, the greatest number was tired eyes accounting for 34%. In the visual symptoms, blurred vision was the highest rate of 83% and in case of systemic symptoms, shoulder pain was 38% marked top ranking but other symptoms were also distributed similar rate. The frequency of blinking during VDT work decreased significantly comparing with the one at rest. The average frequency of blinking is 8/min during VDT work and 22/min at rest. The BUT measured immediately after VDT work decreased much more than in the resting state. The average BUT was 7sec immediately after VDT work and 12sec at rest. The height of palpebral fissure during VDT work increased significantly comparing with the value at rest. The average height of palpebral fissure was 7.69mm at rest and 9.04mm during VDT work. The average visual acuity decreased almost 9.5% from 0.63 to 0.57, but refraction with retinoscopy increased about 0.28D to the direction of myopic shift. The amplitude of accommodation decreased approximately 1.49D from 7.98D to 6.49D and this resulted from the prolongation of near point of accommodation. Near point of convergence also was prolongated from 9.45cm to 10.30cm after VDT work.

• Journal of Energy Engineering
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• v.5 no.2
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• pp.115-122
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• 1996

Heat transfer characteristics of low temperature latent heat storage systems have been examined for the circular finned and unfinned tubes using Na$_2$B$_4$O$\_$7/10H$_2$O as a phase change material. In order to reduce the supercooling of PCM, 3 wt% of Na$_2$B$_4$O$\_$7/10H$_2$O was added as the nucleating agent and 2.2 wt% of acrylic acid sodium sulfate was used as the thickener. The heat storage vessel has dimension of 530 mm height, 74 mm 1.D. and inner heat transfer tube is 480 mm height and 13.5 mm O.D. Water was employed as the heat transfer fluid. During the heat recovery experiment, the heat recovery rate was affected by the flow rates and inlet temperature of heat transfer fluid. The enhancement of heat transfer by fins over the unfinned tube system was found to be negligible in the thin finned tube systems, whereas the heat transfer coefficient in the thick finned tube system is approximately 60% higher than that in the unfinned lobe system. The experimentally determined heat transfer coefficient for the unfinned tube and thick finned tube systems are 150-260 W/㎡$^{\circ}C$ and 230-530 W/㎡$^{\circ}C$, respectively. The fin efficiency based on the heat transfer coefficient and area increased by fins was found to be 0.05 and 0.26 for the thin and the thick finned tube systems.

• Microbiology and Biotechnology Letters
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• v.33 no.4
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• pp.248-254
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• 2005

One hundred thirty nine bacteria were isolated from rotten onions collected from main producing districts, Chang-Nyung, Eui-Ryung, and Ham-Yang in Korea. The $18\%$ (25 strains) of bacterial isolates have carboxymethylcellulase (CMCase) activity and the $53\%$ (74 strains) have polygalacturonase (PGase) activity. Thirty one among randomly selected 45 strains of PGase producing bacteria have pathogenicity to onions. The isolates were classified into Pseudomonas sp. (18 strains), Bacillus sp. (11 strains), Yers-inia sp. (7 strains), and others (9 strains) on the basis of FAMEs patterns. Eighteen strains of Pseudomonas sp. were mainly divided into three cluster in the dendrogram and only the two clusters of them showed pathogenicity to onions. CMCase and PGase activities of Pseudomonas sp. weaker than those of Bacillus sp.. However, the pathogenicity of pseudomonas sp. to soften onions was stronger than that of Bacillus sp. Inoculation of $10^{2}$ cfu of Pseudomonas sp. gives rise to softening of onions. Pseudomonas sp. was identified as Pseudomonas gladioli by biochemical and physiological characteristics. P. gladioli is the first reported bacterium as a pathogen of onion in Korea. In low temperature, P. gladioli showed better growth and higher PGase activity than those of Bacillus sp. identified as Bacillus subtilis. And pH 9.0 is optimal pH for PGase activity of B. subtilis while that of P. gladioli is pH $5.0\∼6.0$ which is the acidity of onions. Taken together, P. gladioli may be a main pathogene of onion rot during the cold storage condition.