• Journal of Power Electronics
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• 제16권6호
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• pp.2272-2283
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• 2016

This paper proposes a power conditioning system (PCS) for distributed photovoltaic (PV) applications using an asymmetric cascaded multilevel inverter with a single PV source. One of the main disadvantages of the cascaded multilevel inverters in PV systems is the requirement of multiple isolated DC sources. Using multiple PV strings leads to a compromise in either the voltage balance of individual H-bridge cells or the maximum power point tracking (MPPT) operation due to localized variations in atmospheric conditions. The proposed PCS uses a single PV source with a flyback DC-DC converter to facilitate a reduction of the required DC sources and to maintain the voltage balance during MPPT operation. The flyback converter is used to provide input for low-voltage H-bridge cells which processes only 20% of the total power. This helps to minimize the losses occurring in the proposed PCS. Furthermore, transient analyses and controller design for the proposed PCS in both the stand-alone mode and the grid-connection mode are presented. The feasibility of the proposed PCS and its control scheme have been tested using a 1kW hardware prototype and the obtained results are presented.

• 산업경영시스템학회지
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• 제41권2호
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• pp.74-83
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• 2018

It is very crucial activities that Korean army have to detect and recognize enemy's locations and types of weapon of their artillery firstly for effective operation of friendly force's artillery weapons during wartime. For these activities, one of the most critical artillery weapon systems is the anti-artillery radar (hereafter; radars) for immediate counter-fire operations against the target. So, in early wartime these radar's roles are very important for minimizing friendly force's damage because arbiters have to recognize a several enemy's artillery positions quickly and then to take an action right away. Up to date, Republic of Korea Army for tactical artillery operations only depends on individual commander's intuition and capability. Therefore, we propose these radars allocation model based on integer programming that combines ArcGIS (Geographic Information System) analysis data and each radar's performances which include allowable specific ranges of altitude, azimuth (FOV; field of view) and distances for target detection, and weapons types i.e., rocket, mortars and cannon ammo etc. And we demonstrate the effectiveness of their allocation's solution of available various types of radar asset through several experimental scenarios. The proposed model can be ensured the optimal detection coverage, the enhancement of artillery radar's operations and assisting a quick decision for commander finally.

• 한국항해항만학회지
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• 제30권5호
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• pp.389-396
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• 2006

최근의 항만 환경에서는 분리된 선석의 통합이 활발히 진행되고 있으며, 통합의 필요성도 높아지고 있다. 그러므로, 기존의 게이트들의 활용이 컨테이너터미널에서의 차량의 체재시간 감소와 차량 통행량 분산 측면에서 검토되어야 한다. 본 연구는 통합게이트와 분리게이트의 운영효과를 분석하였다. 본 연구는 두개의 개별 선석 통합시 게이트 운영의 효율성이 높은 분리게이트시스템을 제안한다.

• 한국항해항만학회:학술대회논문집
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• 한국항해항만학회 2006년도 International Symposium on GPS/GNSS Vol.2
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• pp.373-376
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• 2006

Marine officers should have crisis control ability because ship operation needs not only highly specialized information, but also functional capability due to the fact that there always exist dangers at sea, which are different from those at shore. Therefore, marine officers should be trained on the related specialized information under the systematical educational system including shipboard training. Their training is also based on the strong spiritual power and physical strength through the strict training process. In order to have these vocational personalities, dormitory life training and shipboard training courses seem to be essential processes, which are required of maritime education. The introduction of automatic system into the ship as a result of the recent development of technology brings decrease of the full number of crew. Consequently, marine officers are increasingly under heavy burden, and should have more ship operation capabilities than before. Maine officers should have not only specialized information which differs from that at shore, but also vocational adaptability which can reasonably tackle with all the problems which exist on the spot and are obstacles to individual, spiritual, physical, natural, and social demands. So it is required that marine officers should have study many areas to deal with as extra curricula besides their major field of study, which are unique characteristics of the education for them. These vocational adaptabilities are based on the spiritual characteristics, such as self-developmental education, responsibility, meticulous care, attentiveness, voluntary, planning, readiness, spontaneity, accuracy, self-denial, obedience, leadership, and etc.

• 산업경영시스템학회지
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• 제43권4호
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• pp.76-83
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• 2020

Postal logistics organizations are characterized as having high labor intensity and short response times. These characteristics, along with rapid change in mail volume, make load scheduling a fundamental concern. Load analysis of major postal infrastructures such as post offices, sorting centers, exchange centers, and delivery stations is required for optimal postal logistics operation. In particular, the performance of mail traffic forecasting is essential for optimizing the resource operation by accurate load analysis. This paper addresses a traffic forecast problem of postal parcel that arises at delivery stations of Korea Post. The main purpose of this paper is to describe a method for predicting short-term traffic of postal parcel based on self-similarity analysis and to introduce an application of the traffic prediction model to postal logistics system. The proposed scheme develops multiple regression models by the clusters resulted from feature engineering and individual models for delivery stations to reinforce prediction accuracy. The experiment with data supplied by main postal delivery stations shows the advantage in terms of prediction performance. Comparing with other technique, experimental results show that the proposed method improves the accuracy up to 45.8%.

• 한국의료질향상학회지
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• 제12권1호
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• pp.104-112
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• 2006

Background : The necessity of unify and standardize codes used at hospital has been emphasized since OCS (Order Communicating System) was adopted. Therefore, the purpose of this study were to standardize operation code by continuous training of the ICD-9-CM code that is used as standard code in OCS program at operating room. Method : In 400 operation data, operation code entered in OCS program at operating room was compared to operation name recorded in medical record. In addition, a matching rate between input data of operation code by medical record department and computing input data of operation code in 3,710 cases was compared for each department. User operation name and operation code were matched and major diagnosis by operation department and operation name were also matched. Results : User operation name was reflected in operation classification code in detail, and operation code entered on user was registered. Input rate and matching rate of operation code were gradually improved after improvement activity. In particular, a matching rate was high at ophthalmology where operation name is segmented. Plastic surgery and orthopedics with a lot of emergency operation and comprehensive operation name show low input rates. Conclusions : As the medical field makes progress in computerlization, awareness of information exchange and sharing becomes higher. Among codes to classified medical institution, codes related to surgical operation are all different by user of hospital and department. Computerlization and standardization is essential. And when efforts of standardization continue in alliance with individual hospital and institution, initiative of preparing medical policy data at a national level will be accelerated.

• 디지털산업정보학회논문지
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• 제14권4호
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• pp.189-204
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• 2018

The purpose of this study is to examine an organizational performance difference by individual utilization level of the smart work. The Smart work help minimizing business process and improving organization productivity based on information technology. This new technology provides a flexible way of the task through smart-work center, videoconferencing, telecommuting, mobile(remote control) and business-only messenger. This investment changes organizational culture, institutions and behavior by new technology applying. The organization system change due to smart work has trouble between alteration preferences and existing maintains a group. In response, the organization should make investment justification of smart work for institutional and culture stabilized by a new system in organization. I set up the analytical process of four stages for empirical research. It will analyze an operation difference of the smart work between pre and post investment in the first-step analysis. The two-step analysis will conduct a text mining analysis of smart work operations. The three-step analysis will identify organization performance differences among individual levels in smart work. The four-step analysis will identify a factor difference in organizational performance by individual utilization level on smart work. According to the study, It has been revealed a difference between the pre and post investment performance on smart work. The text mining analyses many appeared an improvement opinion of organizational culture. Next, there is a difference in organization performance among utilize groups of smart work. Furthermore, the factors of organizational performance among groups appeared differently. The theoretical contribution of this study provided to expand the organizational theory of organization change and resistance. The practical implications provided to require a strong guideline an organizational culture and institution for smart work.

• 핵의학기술
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• 제13권1호
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• pp.93-97
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• 2009

2006년~2008년 2사분기까지의 2.5년간의 환자 건수는 14,674건이었으며, $^{18}F$-FDG 평균 주사량은 461.5 MBq 였다. 2.5년간 순환근무는 3회 이루어졌고, 10명의 방사선사 중 PET과 Gamma 영역별 1인을 제외한 8명의 순환근무가 시행되었다. 추가로 2008년 3인의 신입인력이 야간에 투입되어 이에 대한 평가도 이루어졌다. 방사선사의 근무연한은 15년 이상이 2인, 10~15년이 3인, 5~10년이 1인, 5년 미만이 3인이었다. 이들의 개인별 피폭선량은 먼저 PET실에 근무를 하고 있을 때가 Gamma 영역에 근무하고 있을 때 보다 더 높게 나왔다. 가장 큰 원인으로는 일일 처리 건수 면에서 PET과 Gamma영역의 차이가 거의 없는 상태에서 $^{99m}Tc$보다는 상대적으로 에너지가 높은 $^{18}F$-FDG를 사용하는데 있다고 본다. 특히 개인별 피폭선량도 근무연한에 따른 분기별 평가에서 서로 다르게 나타났다. 또한 순환근무 초기 1개월째보다는 업무의 연속성을 익힌 3개월째에 더 낮은 피폭선량을 보여 주고 있다. 이는 PET 실의 근무연한이 길수록 업무의 숙달도가 증가하여 개인별 피폭선량은 감소하는 것으로 보인다. 예약실에 근무하는 간호사의 피폭선량은 $^{18}F$-FDG 주사 후 짧은 시간에 환자와의 접촉이 이루어지고 있어 그리 큰 문제점을 보이지는 않았다. 그러나 임신 가능성이 있는 간호사일 경우는 이를 재고해 보아야할 필요가 있다. 순환 근무를 통한 장시간 PET/CT실을 벗어난 상황이 될 경우 대부분의 근무자가 초기 1개월에서 업무의 연속성 결여 및 개인별 피폭선량 증가라는 위험성을 내포하였다. PET/CT 환자의 증가에 따른 PET/CT실 전체의 과도한 피폭을 분산하기 위한 순환 근무제의 도입이 또 다른 문제점을 갖고 있음을 알 수 있다.5,6) 이를 해결하기 위해서는 근무자의 업무재교육과 순환 및 고정 근무제의 적절한 병행을 시행할 필요가 있다고 본다. 또한 고정 근무자는 순환 근무 인력들의 이런 문제점을 해결하기 위해 업무영역에서 표준화된 업무지침서 등을 만들어야 한다.

• 한국항행학회논문지
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• 제22권4호
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• pp.319-324
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• 2018

본 논문은 RF 전력 반도체를 사용한 고출력 전력증폭기를 구현한 것으로 기존의 플라즈마 발생 장치에 사용되는 마그네트론 방식의 고출력 증폭기 문제점인 낮은 효율과 짧은 수명, 유지 보수의 어려움 그리고 높은 운용비용 등을 개선하기 위한 것이다. 구현된 고출력 전력증폭기는 2.45 GHz ISM (industrial scientific medical) 대역에서 공간 결합방식을 이용한 저 손실, 고출력 레디알 결합기와 반도체로 3 kW급 출력을 얻기 위해서 300 W 급 전력 증폭기 16개의 증폭기로 구성되어 있다. 또한, 이 증폭기는 개별적인 증폭기에 수냉 방식의 구조를 적용하여 고출력에 따른 발열문제를 극복하였다. 소형 시스템으로 구성된 이 전력증폭기는 원하는 출력에서 50%의 높은 효율을 얻었다.

• 한국농림기상학회지
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• 제17권4호
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• pp.290-305
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• 2015

필지단위 재해발생 가능성을 적절한 대응방안과 함께 재배농가에게 농장 맞춤형으로 전달할 수 있는 '농업기상재해 조기경보 시스템'의 실용성과 운영 효율성을 높이기 위하여 현업 서비스 시스템을 국립농업과학원에 구축하여 2014년도 10월부터 2015년 3월까지의 시범 서비스 운영기간 동안 현장 적용을 위한 개선, 서비스 안정화 단계를 거쳤다. 현업 서비스 시스템은 섬진강 하류 유역(행정구역상 광양시 일부, 하동군 일부, 구례군 일부)의 약 470 자원농가와 950 여필지를 서비스 대상으로 하였다. 자원농가에게 필지 단위 사전경보를 개별 문자로 통보하는 시스템과 해당 지자체가 관내 현황을 시각적으로 파악할 수 있는 분포형 사전 경보시스템(웹 GIS 기반) 형식의 투 트랙(Two track) 시스템으로 구성되었다. 1차 연구대상지역인 섬진강 하류에 대하여 현업 서비스는 2015년 3월 2일부터 개별 문자통보를 개시하였으며 온라인 홈페이지는 2015년 4월부터 인터넷 주소(http://www.agmet.kr)로 운영을 시작하였다. 현재는 농장 날씨정보, 농장 재해정보, 전국기상위험, 전국기상특보, 문자서비스를 제공하고 있으며 연구가 진행되는 2017년까지 서비스 대상지역 확대, 서비스 컨텐츠 확대, 서비스 품질 개선 등의 연구활동과 함께 지속적으로 유지될 것이다.