• Journal of Forest and Environmental Science
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• v.33 no.4
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• pp.257-269
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• 2017

The study has piloted to find the Pattern of species distribution along environmental variables and disturbance in Raghunandan Reserve Forest. Shaltila and Shahapur beat of Raghunandan Hill Reserve Forest are situated in Chunarughat sub-district of Habiganj district between $24^{\circ}5^{\prime}-24^{\circ}10^{\prime}N$ and $91^{\circ}25^{\prime}-91^{\circ}30^{\prime}E$ under the Sylhet Forest Division. The Environmental variable and vegetation data were collected from 30 sample plots from each forest beat by using arbitrary sampling without preconceived bias. 51 species were found from Shaltila and 34 species found in Shahapur forest beat. Thus the dataset continued with total 85 species in 60 samples. To determine the relationships between tree species distribution and environmental variables, Canonical Correspondence Analysis (CCA) ordination method were performed separately for two forest beat. In CCA ordination, tree species showed significant variation along environmental gradients in terms of soil organic matter and disturbances (p<0.05) in the case of Shaltila forest. Potassium has a significant relationship with axis 1 and axis 2 in this forest. But Shahapur forest showed no significant relationship between species and environmental variables. Phosphorus has a significantly negative relationship with axis 2 in this forest. Disturbance played as a critical role of this forest thus influencing the distribution of species. The study showed that the distributions of tree species are strongly influenced by disturbance and organic matter in Shaltila and Shahapur forest beat showed no significant relationship between species and environmental variables. Future research should be included more environmental variables with larger study area that identify the most important environmental forces which will drive by species distribution findings in this forest.

• Culinary science and hospitality research
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• v.17 no.5
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• pp.30-41
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• 2011

This study investigates coffee consumers' perceptions of coffee shops, using the Importance-Performance Analysis and the Fishbein Attitude Model approach. A survey was carried out in coffee shops(2010, 12/6~12/20), and 175 out of 200 copies of questionnaire were returned from the coffee shops. After excluding 27 unusable cases which had an unacceptable level of missing data, 148 cases were used for analysis. The IPA showed that an attractive facade, toilet cleanliness, coffee freshness, coffee taste were included in the area of maintaining good results while coffee price was in the area of concentrating efforts, which coffee shop managers should improve. Also, the analysis using the Fishbein attitude model showed that coffee taste, an attractive facade, toilet cleanliness, and coffee freshness were in order of importance, and Starbucks, Angelinus, Caffebene, and Pascucci are in order of brand preference. Although this study has some limitations(such as self-report, common method bias), it shows significant implications to coffee shop managers.

• Journal of the Society of Naval Architects of Korea
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• v.55 no.3
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• pp.205-214
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• 2018

This paper deals with the experimental study on the hygrothermal ageing effect to the strength of Carbon Fiber Reinforced Plastics (CFRP) materials for marine leisure boat manufactured by vacuum assisted resin infusion method. The experiments performed consist of tensile, flexural and shear tests according to American Society for Testing and Materials (ASTM) and Korean Industrial Standards (KS) test methods. Test coupons are varied from uni-directional(UD, $0^{\circ}$, $90^{\circ}$), Bi-Directional (BD), and Double-Bias (DB) carbon fiber fabrics in conjunction with epoxy resin. The results of tensile test show that tensile strength reduces significantly while not the same degree of reduction is observed for elasticity modulus with respect to the existence of hygrothermal ageing effect. This implies that the tensile strain induced from external load holds steady values but ultimate strength values change widely under hygrothermal ageing effect. In case of the flexural test, $0^{\circ}$ UD shows more strength reduction than $90^{\circ}$ UD while BD has reduced values in both flexural strength and elasticity modulus under hygrothermal ageing effect. It is learned that the bending strain induced from external load and ultimate strength values are reduced with respect to hygrothermal ageing effect. Shear test performed only on DB materials, and the results show marginal reduction in ultimate strength and moderate reduction in elasticity modulus. This means that the shear strain varies more than ultimate shear strength with respect to hygrothermal ageing effect. The experiment conducted in this paper clearly demonstrates the differences in material properties of the CFRP for the consideration of hygrothermal ageing effect. Findings obtained from this experimental study can serve as a fundamental input data for the realistic structural responses of marine leisure boat built in CFRP materials.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.14 no.2
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• pp.534-539
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• 2010

In genomic studies, thousands of features are collected on relatively few samples. One of the goals of these studies is to build classifiers to predict the outcome of future observations. There are three inherent steps to build classifiers: a significant gene selection, model selection and prediction assessment. In the paper, with a focus on prediction assessment, we normalize microarray data with quantile-normalization methods that adjust quartile of all slide equally and then design a system comparing several methods to estimate 'true' prediction error of a prediction model in the presence of feature selection and compare and analyze a prediction error of them. LOOCV generally performs very well with small MSE and bias, the split sample method and 2-fold CV perform with small sample size very pooly. For computationally burdensome analyses, 10-fold CV may be preferable to LOOCV.

• Proceedings of the KIEE Conference
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• 2006.07c
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• pp.1438-1439
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• 2006

$Ge_{2}Sb_{2}Te_5$(GST) thin film at present is a promising candidate for a phase change random access memory (PCRAM) based on the difference in resistivity between the crystalline and amorphous phase. PCRAM is an easy to manufacture, low cost storage technology with a high storage density. Therefore today several major chip in manufacturers are investigating this data storage technique. Recently, A. Pirovano et al. showed that PCRAM can be safely scaled down to the 65 nm technology node. G. T Jeonget al. suggested that physical limit of PRAM scaling will be around 10 nm node. Etching process of GST thin ra films below 100 nm range becomes more challenging. However, not much information is available in this area. In this work, we report on a parametric study of ICP etching of GST thin films in $Cl_2$/Ar chemistry. The etching characteristics of $Ge_{2}Sb_{2}Te_5$ thin films were investigated using an inductively coupled plasma (ICP) of $Cl_2$/Ar gas mixture. The etch rate of the GST films increased with increasing $Cl_2$ flow rate, source and bias powers, and pressure. The selectivity of GST over the $SiO_2$ films was higher than 10:1. X-ray photoelectron spectroscopy(XPS) was performed to examine the chemical species present in the etched surface of GST thin films. XPS results showed that the etch rate-determining element among the Ge, Sb, and Te was Te in the $Cl_2$/Ar plasma.

• Journal of Korean society of Dental Hygiene
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• v.20 no.3
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• pp.269-279
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• 2020

Objectives: Previous studies have reported inconsistent findings in the association between dental diagnostic X-ray exposure and thyroid cancer. This study was a meta-analysis of case-control studies evaluating the association between exposure to dental radiation and the thyroid cancer risk. Methods: We searched the PubMed and EMBASE databases to identify studies on dental radiation and thyroid cancer risks that were published up to September 2018. Quality of studies was assessed using the Newcastle-Ottawa scale. A fixed-effects model was used to estimate pooled odds ratios (ORs) and 95% confidence intervals (CIs) using STATA 14.0. Potential publication biases were evaluated using Egger's test and Begg's funnel plot. Results: From the literature search, we included six case-control studies in this meta-analysis. The meta-analysis using the fixed-effects model found that dental X-ray exposure was associated with 2.34 times increased risk for thyroid cancer (OR=2.34, 95% CI=1.79-3.21). There was no heterogeneity in the data (p=0.662, I² =0%). Egger's test showed that there was no publication bias (p=0.532). Conclusions: This meta-analysis confirmed the association of dental X-ray exposure and thyroid cancer risk. The current results underscore the importance of applying safety regulations at dental clinics to protect thyroid glands during dental radiography examinations.

• Journal of The Korean Society of Agricultural Engineers
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• v.59 no.6
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• pp.9-18
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• 2017

The objective of this study was to estimate the climate change impact on inflow to Namgang Dam using SWAT (Soil and Water Assessment Tool) model. The SWAT model was calibrated and validated using observed flow data from 2003 to 2014 for the study watershed. The $R^2$ (Determination Coefficient), RMSE (Root Mean Square Error), NSE (Nash-Sutcliffe efficiency coefficient), and RMAE (Relative Mean Absolute Error) were used to evaluate the model performance. Calibration results showed that the annual mean inflow were within ${\pm}5%$ error compared to the observed. $R^2$ were ranged 0.61~0.87, RMSE were 1.37~7.00 mm/day, NSE were 0.47~0.83, and RMAE were 0.25~0.73 mm/day for daily runoff, respectively. Climate change scenarios were obtained from the HadGEM3-RA. The quantile mapping method was adopted to correct bias that is inherent in the climate change scenarios. Based on the climate change scenarios, calibrated SWAT model simulates the future inflow and evapotranspiration for the study watershed. The expected future inflow to Namgang dam using RCP 4.5 is increasing by 4.8 % and RCP 8.5 is increasing by 19.0 %, respectively. The expected future evapotranspiration for Namgang dam watershed using RCP 4.5 is decreasing by 6.7 % and RCP 8.5 is decreasing by 0.7 %, respectively.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.16 no.2
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• pp.1036-1044
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• 2015

This paper estimates the relative risk aversion coefficients of apple farmers. Two hypothetical situations are designed and two-stage questionnaires are conducted for each situation. A utility function that has constant relative risk aversion was used, and it was assumed that the relative risk aversion coefficients follow a log-normal distribution. To reduce the hypothetical bias, the data was collected from repetitive questions. As a result, the mean and standard deviation of the relative risk aversion coefficients of apple farmers was 10.915 and 7.516, respectively. The relative risk aversion coefficients conditional on a survey response in each category were also measured. These findings can be used as parameters to analyze the effects of risk management tools.

• Proceedings of the Korean Vacuum Society Conference
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• 2013.08a
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• pp.186-186
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• 2013

종래의 흑연 위주 연료전지 분리판 개발되어 최근 고분자 전해질 막 연료전지가 높은 전력, 낮은 배기 가스 배출, 낮은 작동 온도로 자동차 산업에서 상당한 주목을 받고 있다. 요구사항은 높은 전기 전도도, 높은 내식성, 낮은 가스 투과성, 낮은 무게, 쉬운 가공, 낮은 제조비용이다. Thin film Cr 장비로 저항가열 furnace, sputter 등이 사용된다. 연료전지 분리판의 고전도도, 내부식성 보호막의 고속 증착을 위한 새로운 증착원으로 스퍼터 - 승화형 소스의 가능성을 유도 결합 플라즈마에 금속 봉을 직류 바이어스 함으로써 시도하였다. 유도 결합 플라즈마를 이용하여 승화증착 시스템을 사용하여 OES (SQ-2000)와 QMS (CPM-300)를 사용하여 $N_2$ flow에 따른 유도 결합 플라즈마를 이용한 스퍼터-승화증착 시스템을 사용 하여도 균일한 공정을 하는 것을 확인 하였다. 5 mTorr의 Ar 유도 결합 플라즈마를 2.4 MHz, 500 W로 유지하면서 직류 바이어스 전력을 30 W (900 V, 0.02 A) 인가하고, $N_2$의 유량을 0.5, 1.0, 1.5 SCCM로 변화를 주어 특성을 분석하였다. MID (Multiple Ion Detection) mode에서 유도결합 플라즈마를 이용한 스퍼터-승화 증착 장비를 사용하여 CrN thin flim 성장시켰고, deposition rate은 44.8 nm/min으로 얻을 수 있었다. 또한 $N_2$의 유량이 증가할 수록 bias voltage가 증가하는 것을 확인 할 수 있었다. OES time acquisition을 이용한 공정 분석에서는 $N_2$ 유량을 off 하였을 때 Ar, Cr의 중성 intensity peak이 상승하였고, 시간 경과에 따라 sublimation에 의한 영향이 없는 것을 확인 할 수가 있었다. XRD data에서는 질소 유량이 증가함에 따라 $Cr_2N$이 감소하고, CrN이 증가하는 것을 확인할 수가 있었다. 결정배향성과 Morphology는 다결정 재료의 경도에 영향을 주는 인자이다. CrN 결정 구조의 경우는 (200)면이 경도가 제일 높은데 (200)면에서 성장한 것을 확인 할 수 있었다. 잔류가스 분석 결과로는 일정한 Ar의 유량을 흘렸을 때 $N_2$의 변화량이 비례적인 경향이 보이는 것을 확인 할수 있었다. 또한 $N_2$가 흐르면서도 유도 결합 플라즈마를 이용한 스퍼터-승화 증착 시스템을 사용하면 일정한 공정을 하는 것을 확인 할 수 있었다. 질소의 분압이 유량에 따라서 $3.0{\times}10^{-10}$ Torr에서 $1.65{\times}10^{-9} $Torr까지 일정한 비율로 증가한다. 즉, 이 시스템으로 양산장비 설계를 하여도 가능 하다는 것을 말해준다.

• Journal of Physiology & Pathology in Korean Medicine
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• v.34 no.3
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• pp.117-125
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• 2020

The purpose of this review is to confirm whether Soyo-san (Xiaoyao-san) and its modifications is effective on alleviating clinical symptoms in chronic fatigue syndrome (CFS) patients. We collected clinical trials (randomized controlled trial, quasi-randomized controlled trial, controlled clinical trial) to investigate the effects of Soyo-san and its modifications on general symptoms, fatigue, depression and anxiety in CFS patients. The databases used for data retrieval were Pubmed, Central Cochrane, Embase, CNKI, CQVIP, Wanfang, CiNii, OASIS, RISS, and Koreamed. We performed selection/exclusion process from the found studies to conform with prespecified criteria, and assessed the final included trials according to the Cochrane risk of bias tool. The included studies were classified based on the interventions in experimental and control group. Eight randomized controlled trials and one controlled clinical trial (total 921 participants) were eligible and their results were synthesized in the meta analysis. The synthesis showed a considerable effect of Soyo-san and its modifications on improvement of general symptoms (relative risk 0.27 [95% CI 0.19 to 0.39], Z=7.03, P<0.00001; I2=0%) and fatigue severity (SMD -1.20 [95% CI -1.46 to -0.93], Z=8.78, P<0.00001; I2=52%) in CFS patients, while Effect on depression and anxiety were inconclusive. We found that Soyo-san and its modifications were effective for improvement of general symptoms and fatigue severity in CFS post-treatment.