• Proceedings of the Korean Society of Agricultural Engineers Conference
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• 2005.10a
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• pp.266-271
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• 2005

In this study, following works have been carried out : division of Nakdong River Basin into 25 sub basins, development of a technique to evaluate spatial distribution of rainfall and analysis of rainfall data of 169 stations, selection of control points, and selection of a hydrologic model(SSARR). The runoff analysis showed that the surface-subsurface separation and soil moisture index parameters are the most important two to the simulation result.

• Journal of Industrial Technology
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• v.18
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• pp.439-442
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• 1998

In this paper, we firstly suggested C&D (Common mode and Differential mode) model for the representation of a stereophonic signal. Then a measure of stereophonic channel separability is defined as the ratio of differential mode energy to total energy in frequency domain. After that, a new channel separability enhancement scheme is proposed by the control of common mode rejection. Finally, some experimental results are presented in order to verify our scheme.

• Current Optics and Photonics
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• v.3 no.4
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• pp.298-303
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• 2019

We propose a photonic quasi-crystal fiber (PQF) for supporting up to 14 orbital angular momentum (OAM) modes with low and ultra-flat dispersion characteristics over the C+L bands. The designed PQF which consists of a large hollow center and quasi structural small air holes in the clad region exhibits low confinement losses and a large effective index separation (>$10^{-4}$) between the vector modes. This proposed fiber could potentially be exploited for mode division multiplexing and other OAM mode applications in fibers.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.23 no.11
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• pp.891-895
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• 2010

Polymer dispersed liquid crystal (PDLC) films were prepared by the phase separation method using the liquid crystal (E7) and prepolymers. This work investigated the electro-optical characteristics of various PDLC films. In order to have good contrast ratio, the polymer refractive index must be adjusted to the ordinary refractive index of the liquid crystal. The driving voltage of PDLC films were mainly affected by elastic deformation. E7-Ebecryl810-IOA-TMPTA-HMPPO system had good threshold voltage and driving voltage and E7-Ebecryl810-EHA-PEGDA-HMPPO system had good contrast ratio.

• Proceedings of the KSR Conference
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• 2007.05a
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• pp.594-599
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• 2007

According to separation policy between rail infrastructure and operation, the National Railroad Administration was converted to Korea Railroad Cooperation on Jan, 2005. That makes railway service assessment regarded as essential. About this matter, Section 15 of the Framework Act on Rail Industry Development and section 26 of the Rail Business Act shows that the railway service assessment should be conducted every 2 years. The government can officially announce the result and give orders operation company to improve service level. In the first railway service assessment in 2006, the principal railroad lines and stations were investigated. Rail supply service index and customer satisfaction index are introduced. It includes service items of supply, reliability, convenience, safety and customer satisfaction. This study presents the contents of 2006 rail service assessment. Some points of assessment which should be improved are analyzed as well.

• 한국정보디스플레이학회:학술대회논문집
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• 2009.10a
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• pp.902-903
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• 2009

Polymer Dispersed Liquid Crystal (PDLC) films were prepared using the phase separation method with liquid crystal and a newly developed prepolymer. This study investigated the electro-optic characteristics of the PDLC film at various temperatures. It was found that as temperatures increased, the voltage varied, and that the ordinary refractive index of the liquid crystal and the polymer refractive index in the composite had similar dependence at various temperatures.

• Journal of Industrial and Engineering Chemistry
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• v.67
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• pp.123-131
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• 2018

Using mixed nonionic surfactants Span/Tween, we investigated the effects of HLB value on the O/W emulsion stability and rheological behaviors. In this study, MS-01 (Span 60 & Tween 60) and MS-02 (Span 80 & Tween 80) was used as mixed nonionic surfactants. We considered required HLB value 10.85 and selected corresponding HLB value range 8-13. The droplet size distributions, droplet morphology, rheological properties, zeta-potential and creaming index of the emulsion samples were obtained to understand the mechanism and interaction of droplets in O/W emulsion. The results indicated that optimal HLB number for O/W emulsions was 10.8 and 10.7, while using MS-01 surfactant and MS-02 surfactant respectively. MS-01 (HLB = 10.8) sample and MS-02 (HLB = 10.7) sample showed smallest droplet size and highest zeta-potential value. Rheological properties are measured to understand rheological behaviors of emulsion samples. All emulsion samples showed no phase separation until 30 days storage time at $25^{\circ}C$.

• Korea Journal of Hospital Management
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• v.10 no.4
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• pp.51-74
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• 2005

This paper presents an analysis of the current status of domestic hospital industry which went trough the time of new hospitals operated by chaebols from 1994 to 2003 and the dramatic changes of medical service environment such as IMF relief loan in 1997 and the separation of prescription and dispensing (SPD) in 2000. For the sake of righteous policy-making in the future, this paper presents a productivity analysis of the management and administration of 38 tertiary hospitals nationwide in the past 10 years. The analysis is based on the Malmquist index approach using linear programming. d prepare a productivity index that measures not merely efficiency but the technological evolution and adjustment to changing environments.

• The Korean Journal of Health Service Management
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• v.5 no.1
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• pp.77-85
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• 2011

The study intends to conduct an analysis of relations between efficiency of investment to human resources and the operating margin in hospitals. The analyzed results are as follows: First, it is found out that an index related to labor productivity(the monthly value added per bed, the value added ratio to gross revenue), and an index for efficiency of human resources(value added to personnel expenses), do not have a significant difference by years. Second, labor productivity, indicating the efficiency of human resources, does not have a significant difference between regions and between hospital types. But there is a significant difference according to types of establishment: private hospitals have higher labor productivity(efficiency of human resources) than corporate hospitals. The hospital size is small have significantly higher labor productivity. As a result of a follow-up check, it is found out that there is separation between a group with more than 200 beds and a group with less than 200 beds. Third, at the relations between the indices related to value-added productivity and the operating margin that the higher the value added ratio to gross revenue and the higher labor productivity, the higher the operating margin. Especially, labor productivity(value added to personnel expenses), an index for the efficiency of human resources, out of all the indices related value added productivity, has the most significant influence on the operating margin.

• Proceedings of the Korea Water Resources Association Conference
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• 2018.05a
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• pp.171-171
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• 2018

댐 유입량의 구성을 이해하는 것은 직접유출과 기저유출의 특성에 따라 수자원확보, 물 공급, 관개용수, 수력발전, 생태계 서식지, 친수활동 등 계절별 댐 운영을 효율적으로 수행하는데 기여할 수 있다. 또한, 댐은 대부분 유역 상류에 위치해 있어 댐 유입유량에 있어 다른 수리구조물에 의한 영향이 상대적으로 작기 때문에 앞에서 제시한 인위적 영향을 제외한 기저유출분리를 수행 할 수 있다. 이와 관련하여 본 연구의 목적은 1)댐 유입량에 대한 연별, 월별 기저유출을 분석하고; 2) 유역 상 하류에 위치한 댐의 유입량에 대하여 기저유출 기여도를 비교하는 것이다. 두 개의 연계 댐에 대하여 인위적 영향이 적은 상류에 위치한 댐이 하류에 위치한 댐보다 Baseflow Index가 더 작은 결과를 보여주었다. 상류 수자원시설부터 인위적 방류는 하류의 댐 유입량의 Baseflow Index를 과다산정의 원인이 될 수 있다는 것으로 나타났다. 본 연구의 결과는 댐 유입량의 특성을 월별 연별로 분석함으로써 댐의 역할과 기능을 확대하고 효율적 상 하류 댐 연계운영에 기여할 것으로 기대한다.