• 전기학회논문지
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• 제57권6호
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• pp.1081-1086
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• 2008

This paper presents the $3^{rd}$ 4bit sigma delta modulator with the block and timing diagrams of DWA(Data Weighted Averaging) to optimize a operating time. In the modulator, the proposed DWA structure has a stable operation and timing margin so as to remove three latches and another clock. Because the modulator with proposed DWA structure improve timing margin about 23%. It can increase sampling frequency up to 244MHz. Through the MATLAB modeling, the optimized coefficients are obtained to design the modulator. The fully differential SC integrators, DAC, switch, quantizer, and DWA are designed by considering the nonideal characteristics. The designed $3^{rd}$ order 4bit modulator has a power consumption of 40mW and SNR(signal to noise ratio) of 77.2dB under 1.2V supply and 64MHz sampling frequency.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2007년도 추계학술대회 논문집 전력기술부문
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• pp.237-239
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• 2007

This paper focuses on maintenance scheduling using PSO algorithm for power plants from an economic (operating cost) and reliable(variance of operating reserve margin) point of view. We also apply regional reserve margin and transfer capability to maintenance scheduling problem. The proposed method has been applied to IEEE-RTS(1996) with 32-generators and a real -world large scale power system with 291 generators.

• 한국병원경영학회지
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• 제18권3호
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• pp.43-61
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• 2013

The purpose of this study is to analyze the relations between publicness and profitability of national university hospitals in Korea. Finance and management data from 2008 to 2010 were collected from balancing accounts and annual reports in 13 national university hospitals. The dependant variables are used profitability indicators which are operating margin, net profit to gross revenues, normal profit to gross revenues. The independent variables are publicness indicators which are medical social work, ratio of medical aid in inpatients, ratio of medical aid in outpatients, publicness index. The results show that operating margin, net profit to gross revenues in profitability indicators are affected by medical social work in publicness indicators. Normal profit to gross revenues in profitability indicators is strong related to medical social work and hospital province in publicness indicators. Based on these results, this study suggests implications to balance the publicness and the profitability in national university hospitals.

• 한국유체기계학회 논문집
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• 제14권2호
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• pp.35-40
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• 2011

This study analyzed the influence of firing biogas on the performance and operation of a gas turbine combined heat and power (CHP) system. A reference CHP system designed with natural gas fuel was set up and off-design simulation was made to investigate the impact of firing biogas in the system. Changes in critical operating parameters such as compressor surge margin and turbine blade temperature caused by firing biogas were examined, and a couple of operating schemes to mitigate their changes were simulated. Part load operation of the biogas-fired system was compared with that of natural-gas fired system, and it was found that as long as the two system produce the same electric power output, they exhibit nearly the same heat recovery.

• 한국유체기계학회 논문집
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• 제14권6호
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• pp.68-75
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• 2011

This study simulated the effect of steam injection on the performance and operation of a gas turbine combined heat and power (CHP) system. A commercial simple cycle gas turbine was analyzed. A full off-design analysis was carried out to investigate the variations in not only engine performance but also the operating characteristics of the compressor caused by steam injection. Variation in engine performance and operation characteristics according to various operation modes were examined. First, the impact of full steam injection was investigated. Then, operations aiming to guarantee a minimum compressor surge margin, such as under-firing and partial steam injection, were investigated. The former and latter were turned out to be relatively superior to each other in terms of power and efficiency, respectively.

• 한국병원경영학회지
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• 제25권4호
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• pp.48-59
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• 2020

Purposes: The purposes of this study is analysis of business performance in national university hospitals in Korea. Methodology: Data from 2010 to 2019 were collected from balance sheet, income statement, and annual reports in 11 national university hospitals. The dependant variables are business performance which are operating margin to total assets, operating margin to gross revenue, and net income to gross revenue. The independent variables are the number of bed, hospital location, opening, liquidity, stability, and activity. Findings: In recent years, activity has been shown to have a lot of influence on management performance. National university hospitals increase profitability by using resources as efficiently as possible. The short-term debt and fixed assets have been increased rapidly in recent years. It was found that management performance has been increased through active investment using financial leverage. Practical Implications: Based on these results, this study will be the basic data for efficient management of national university hospitals.

• 대한기계학회논문집B
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• 제37권11호
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• pp.1015-1022
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• 2013

본 연구에서는 현재 개발중인 200kW 급 마이크로 가스터빈의 운전 특성을 모사하였다. 세부적인 성능 데이터를 이용하여 부분부하 제어방식(터빈 입구온도 제어방식(constant TIT control)과 터빈 출구온도 제어방식(constant TET control))과 외기온도에 따른 성능 및 작동특성을 분석하였다. 넓은 운전 범위에 대하여 압축기 서지마진과 터빈 입출구 온도 같은 작동 파라미터의 민감도를 단위 연료량 변화에 따라 예측하였다. 정상상태 계산으로 부분부하 변동 시 최대서지마진의 감소에 대한 정보를 민감도 분석을 통해 알 수 있다.

• The Journal of Asian Finance, Economics and Business
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• 제8권11호
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• pp.223-234
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• 2021

This study aims to examine whether operating cash flows influence banks' financial stability in Pakistan. The study employed annual panel data collected from annual reports of 20 commercial banks listed on the Pakistan Stock Exchange for the year 2011 to 2019. Free cash flow yield was taken as the dependent variable while cash flow ratio was selected as the independent variable, and net interest margin, income diversification, asset quality, financial leverage, the cost to income ratio, advance net of provisions to total assets ratio, capital ratio, financial performance, breakup value per share and bank size were taken as control variables. The study performed ordinary least square technique, random and fixed effects models, Hausman test, Lagrange multiplier test, descriptive and correlation analysis. Results showed that operating cash flows and net interest margin significantly and positively influenced banks' financial stability while the cost to income ratio and advances net of provisions to total assets ratio significantly and negatively associated with banks' financial stability. To improve financial stability, banks should become more cost-effective and enhance their liquidity levels by lowering lending activities. In the future, it would be useful to compare commercial and investment banks, also Islamic and conventional banks in the same research setting.

• 한국콘텐츠학회논문지
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• 제9권6호
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• pp.196-206
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• 2009

병원의 수익성이란 병원이 회계년도 기간동안 환자 진료 및 기타 경영활동을 통해 달성한 경영성과를 말한다. 본 연구는 병원의 수익성 측정 지표로 병원을 운영하여 얻은 의료수익에서 의료비용을 뺀 순수한 의료이익인 의료수익의료이익율을 사용하였다. 이를 통해 수익성에 영향을 미치는 다양한 지표를 대상으로 병원 수익성 관련 요인을 도출하였다. 이 결과를 토대로 병원의 수익성 제고 방안을 강구할 수 있는 보다 유용한 기초자료를 산출하고자 하였다. 분석결과 공공병원이 민간병원보다 수익성이 낮았다. 각 지표의 수익성을 적자병원군과 흑자병원군으로 구분하여 분석한 결과 인건비 비율, 관리비 비율, 전문의 1인당 수술건수, 의료장비 회전율와 관련한 지표에서 유의한 차이를 보였다. 관련 지표가 수익성에 미치는 영향을 보면 모형에 따라 설명력은 25%-74.5%였다.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2000년도 하계학술대회 논문집 A
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• pp.3-6
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• 2000

In this paper the concept of voltage stability operating limit in optimal power flow problem is described. A methodology of optimal power flow considering voltage stability margin is proposed based on auxiliary constraint to get a secure dispatch solution. The look-ahead margin is used to shift dispatch solutions to the secure direction in proposed framework. The a1gorithm proposed is successfully tested on IEEE 30-bus system.