• 한국환경과학회지
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• 제26권8호
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• pp.993-998
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• 2017

De-icing salts applied to roads during winter enable safe driving conditions. However, these salts are eventually displaced to roadside areas at which they can negatively impact soil, vegetation, and water resources. This purpose of this study is to determine the relationship between foliar damage ratio (NY = 0-25%, SY = 26-50%, CY = 51-75%) on roadside trees (Ginko biloba) and seasonal impact of de-icing salts on soil and vegetation. Thirty roadside trees were selected at 8 m intervals between the Konkuk and Judeok intersections in Chung-ju city. The results reveal that seasonal soil acidity is relatively alkaline for foliar damage ratio of Ginko biloba was CY compared to NY. Also, electronic conductivity of each seasonal sampling was recorded as high in winter and spring, whereas the opposite trend is observed in summer. Various plants species were identified in abundance under roadside trees within NY roadside sections. These same species were observed in reduced numbers within CY sections. Strong negative correlations were identified between foliar damage ratio on roadside trees and vegetation. This relationship may be a method to use in predicting the accumulation of de-icing salt and visible injuries on roadside trees.

• 한국환경복원기술학회지
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• 제19권3호
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• pp.1-9
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• 2016

The objective of this study was to exam early stages of plant growth of Euonymus fortunei 'Emerald and Gold' and Hedera japonica grown in fabric felt bag attached on vertical greenery system with the ratio of hydrophilic polymer to substrate, 0(referred as Control), 0.1, 0.2, or 0.4% (v/v), in order to effectively utilize rainfall for low maintenance. After rainfall, the increase in volumetric water content of substrate amended with the hydrophilic polymer was between 13% and 87%, compared to that in Control. During drought period, higher ratio of hydrophilic polymer to substrate slowly decreased the volumetric water content, and increased plant height, leaf length, leaf width, number of leaves, branch number, and stem diameter of both Euonymus fortunei 'Emerald and Gold' and Hedera japonica with the highest fresh and dry weights of shoots or roots under the 0.1% ratio of hydrophilic polymer.

• Korean Journal of Ophthalmology
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• 제32권6호
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• pp.483-487
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• 2018

Purpose: To compare the characteristics and surgical outcomes in patients with tenacious proximal fusion (TPF) and high accommodative convergence/accommodation ratio (AC/A) types of intermittent exotropia. Methods: This study retrospectively enrolled 40 patients with intermittent exotropia, 23 with TPF and 17 with high AC/A. Binocular function was evaluated by Worth's 4-dot test. Patients underwent lateral rectus recession, and surgical outcomes were compared. Surgical success was defined as less than ${\pm}10$ prism diopters (PD) at 12 months postoperatively. Results: The proportion of diplopia at near, evaluated by Worth's 4-dot test, was significantly higher in patients with high AC/A than in those with TPF (35.3% vs. 4.3%, p = 0.029). The mean preoperative angles of deviation in TPF and high AC/A types were $28.3{\pm}4.4$ and $28.8{\pm}4.5PD$ at distances, and $14.7{\pm}4.2$ and $15.1{\pm}4.1PD$ at near. Twelve months after surgery, the mean angles of deviation in TPF and high AC/A types were $2.9{\pm}9.8$ and $1.2{\pm}9.6PD$, respectively, at distance and $1.7{\pm}7.7$ and $-1.3{\pm}11.3PD$ at near. The surgical success rates were similar in the TPF and high AC/A types (74.0% vs. 64.7%). Five (21.7%) patients with TPF and 2 (11.8%) with high AC/A type experienced recurrence, with consecutive esotropia occurring in 1 (4.3%) patient with TPF and 4 (23.5%) patients with high AC/A. Conclusions: The proportion of diplopia at near was higher in patients with high AC/A type than in those with TPF intermittent exotropia. However, the surgical success rates were not significantly different between the types.

• 한국디지털정책학회:학술대회논문집
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• 한국디지털정책학회 2006년도 추계학술대회
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• pp.327-336
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• 2006

The odds ratio is used for assessing the disease-exposure association, because epidemiological data for case-control of cohort studies are often summarized into 2 ${\times}$ 2 tables. In this paper we define the odds ratio function(ORF) that extends odds ratio used on discrete survival event data to continuous survival time data and propose estimation procedures with censored data. The first one is a nonparametric estimator based on the Nelson-Aalen estimator of comulative hazard function, and the others are obtained using the concept of empirical odds ratio. Asymptotic properties such as consistency and weak convergence results are also provided. The ORF provides a simple interpretation and is comparable to survival function or comulative hazard function in comparing two groups. The mean square errors are investigated via Monte Carlo simulation. The result are finally illustrated using the Melanoma data.

• 한국융합학회논문지
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• 제10권5호
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• pp.407-415
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• 2019

본 논문은 아르바이트를 경험한 청소년의 식습관과 건강위험행위의 위험도를 비교 분석하고자 시행되었다. 제13차(2017년) 청소년 건강행태 온라인 자료를 바탕으로 SPSS 24.0을 이용하여 기술통계, 복합표본 다중 로지스틱 회귀분석을 진행하였다. 아르바이트를 경험한 청소년이 경험하지 않은 청소년보다 과일을 섭취하지 않는 비율이 1.20배 (CI: 1.10-1.31) 높았고, 반면에 패스트푸드는 1.28배 (CI: 1.19-1.38) 더 많이 섭취하고 있는 것으로 나타났다. 건강위험행위는 현재 흡연의 경우 아르바이트를 경험한 청소년이 경험하지 않은 청소년보다 3.48배(CI: 3.17-3.84), 현재 음주는 3.36배(CI: 3.14-3.96), 고카페인 섭취는 1.11배(CI: 1.04-1.19), 위험 성행동은 2.29배(CI: 2.06-2.55) 더욱 높게 나타났다. 따라서 청소년을 대상으로 보건교육프로그램 개발 시 아르바이트 경험 여부에 따른 식습관과 건강위험행위에 관한 내용이 포함되어야 할 필요가 있다.

• Composites Research
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• 제33권6호
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• pp.336-340
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• 2020

본 연구에서는 헥사 메틸렌 테트라민을 촉매로 사용하여 이소프로판올에서 레소시놀과 퍼푸랄을 졸-겔 중축합한 후 이소프로판올 동결 건조 조건에서 유기 겔을 직접 건조시킨 후 질소 분위기에서 탄화시켜 탄소 에어로겔을 제조하였다. 탄소 에어로겔의 제조 조건은 퍼푸랄에 대한 레소시놀의 몰비를 변경하여 조사하였다. 탄소에어로겔의 기공 구조에 대한 제조조건의 영향은 질소 흡착 등온선에 의해 고찰하였다. 탄소 에어로겔의 특성은 주사전자현미경과 적외선 분광법을 가지고 측정하였다. 전기 이중층 커패시터에서 전극으로서의 탄소 에어로겔의 기공 접근성과 성능을 전기 화학적으로 고찰하였다. 결과적으로 BET 표면적과 비용량은 R/C 비율에 따라 증가하였으며, 765 ㎡/g 및 132 F/g의 최대 값은 각각 R/C 비율 200에서 달성되었다. 결론적으로 R/C 비율을 높이면 CA 전극의 평균 기공 크기가 증가하여 시스템의 속도 성능이 향상됨을 확인하였다.

• 한국기계가공학회지
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• 제21권8호
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• pp.79-86
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• 2022

With the recent increase in the demand for electric vehicles, it is necessary to identify the high current safety of automobile parts. Among the automobile parts, the EPDM parts required colored parts from the existing black; therefore, it was necessary to change the basic filler from carbon black to silica. The rubber used in automobile parts is flexible and exhibits basic characteristics of high strength and elongation. However, as the filler is changed to silica, its physical properties, such as tensile strength and elongation, are lower than those of the existing carbon black base. Therefore, it is necessary to evaluate the mechanical properties with the addition of the EPDM compound using silica as a base without degrading the physical properties of EPDM. In this study, an experiment based on the additive content was performed using the mixture experimental planning method to analyze the mechanical properties according to the additive type and mixing ratio of silica-based EPDM. The mixing ratio of the four additives was set using a simplex lattice design, and the tensile strength, elongation, modulus 300%, and permanent compression reduction rate were analyzed for mechanical characteristics, and rheometer experiments were performed for vulcanization characteristics. Through statistical analysis of the measured data, the main effects and interactions of the EPDM-blended rubber additives were analyzed. These results can be used to derive a mixing ratio of additives that satisfies the required characteristics of the EPDM compound.

• Current Photovoltaic Research
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• 제11권3호
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• pp.67-74
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• 2023

The earth-abundant element-based Cu₂ZnSn(S,Se)₄ (CZTSSe) thin film solar cells (TFSCs) have attracted greater attention in the photovoltaic (PV) community due to their rapid development in device power conversion efficiency (PCE) >13%. In the present work, we demonstrated the fine-tuning of the bandgap in the CZTSSe TFSCs by altering the sulfur (S) to the selenium (Se) chalcogenide ratio. To achieve this, the CZTSSe absorber layers are fabricated with different S/(S+Se) ratios from 0.02 to 0.08 of their weight percentage. Further compositional, morphological, and optoelectronic properties are studied using various characterization techniques. It is observed that the change in the S/(S+Se) ratios has minimal impact on the overall Cu/(Zn+Sn) composition ratio. In contrast, the S and Se content within the CZTSSe absorber layer gets altered with a change in the S/(S+Se) ratio. It also influences the overall absorber quality and gets worse at higher S/(S+Se). Furthermore, the device performance evaluated for similar CZTSSe TFSCs showed a linear increase and decrease in the open circuit voltage (V_oc) and short circuit current density (J_sc) of the device with an increasing S/(S+Se) ratio. The external quantum efficiency (EQE) measured also exhibited a linear blue shift in absorption edge, increasing the bandgap from 1.056 eV to 1.228 eV, respectively.

• Current Optics and Photonics
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• 제1권2호
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• pp.157-162
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• 2017

In large liquid crystal displays, the image quality in an oblique viewing direction is a crucial issue. From this perspective, 8-domain polymer-stabilized vertical alignment (PS-VA) mode has been developed to suppress the color shift in oblique viewing directions, compared to that in 4-domain PS-VA mode. To realize the 8-domain PS-VA, the four domains in a pixel are each divided into two regions, such that applying different electric potentials result in different tilt angles in these two regions, while keeping four azimuthal directions in each domain. However, applying different voltages in a pixel causes drawbacks, such as requiring additional processes to construct a capacitor and a transistor, which will further reduce the aperture ratio. Here we propose a different approach to form the 8-domain, by controlling surface polar anchoring energy and the width of patterned electrodes in two regions of a pixel. As a result, the gamma-distortion index (GDI), measured at an azimuthal angle of $0^{\circ}$, is reduced by about 23% and 8%, compared to that of a conventional 4-domain at polar angles of $30^{\circ}$ and $60^{\circ}$ respectively.

• 한국융합학회논문지
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• 제12권1호
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• pp.111-118
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• 2021

본 연구는 성별에 따른 한국인의 혈중지질과 치주질환과의 상관성을 연구하기 위해 2016-2018년 국민건강영양조사 원시자료를 이용하여 최종 11,797명을 분석대상자로 하였다. 한국인 남성의 혈중지질과 치주질환과의 관련성을 보기 위한 흡연과 거주지역을 층화하여 분석하였으며. 남성에서 비흡연자가 중성지방 경고 그룹은 OR(odds Ratio) 1.38 배(95% CI:1.09-1.76), 위험 그룹은 OR 1.49배 (95% CI:1.16-1.91)로 치주질환 연관성이 유의하게 나왔으며 흡연자에서도 중성지방 위험 그룹은 OR 1.76배 (95% CI:1.39-2.23) 높아 치주질환과 연관성이 나왔으며 도시지역 거주자 남성은 총콜레스테롤 위험 그룹은 OR 1.48배 (95%CI:1.14- 1.19), HDL 콜레스테롤은 위험 그룹이 OR 1.49배 (95% CI:1.16-1.19), 중성지방은 경고 그룹이 OR 1.14배 (95% CI:1.16-1.70), 위험 그룹은 OR 1.60배 (95% CI:1.32- 1.94) 치주질환 연관성과 유의하다는 결과가 나왔다. 결론적으로 남성의 혈중지질과 치주질환과는 흡연이나 거주지역에 따라 연관성이 있으며 특히 도시지역 남성의 전신질환과 치주질환 관련 보건교육 프로그램을 개발함에 있어서 기초 자료로 활용하고자 한다. 향후 도시지역 남성을 대상으로 하는 교육 프로그램을 개발함에 있어서 기초자료로 활용하고자 한다.