• 대한전기학회논문지:전력기술부문A
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• 제52권6호
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• pp.307-315
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• 2003

This paper proposes a novel simulation method of WPGS (Wind Power Generation System). The rotation speed control method of turbine under variable wind speed using the pitch control is proposed. Moreover, when wind speed exceeds the cut-out wind speed, the turbine will be stopped by controlling pitch angle to 90$^{\circ}$, otherwise it will be controlled to steady-state operation. For the purpose of effective simulation, the SWRW (Simulation method for WPGS using Real Weather condition) is used for the utility interactive WPGS simulation in this paper, in which those of three topics for the WPGS simulation: user-friendly method, applicability to grid-connection and the utilization of the real weather conditions, are satisfied. It is impossible to consider the real weather conditions in the WPGS simulation using the EMTP type of simulators and PSPICE, etc. External parameter of the real weather conditions is necessary to ensure the simulation accuracy. The simulation of the WPGS using the real weather conditions including components modeling of wind turbine system is achieved by introducing the interface method of a non-linear external parameter and FORTRAN using PSCAD/EMTDC in this paper. The simulation of long-term, short-term, over cut-out and under cut-out wind speeds will be peformed by the proposed simulation method effectively. The efficiency of wind power generator, power converter and flow of energy are analyzed by wind speed of the long-term simulation. The generator output and current supplied into utility can be obtained by the short-term simulation. Finally, transient-state of the WPGS can be analyzed by the simulation results of over cut-out and under cut-out wind speeds, respectively.

• 전기학회논문지
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• 제61권11호
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• pp.1758-1764
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• 2012

A large number of wire rope has been used in various inderstiries as Cranes and Elevators from expanding the scale of the industrial market. But now, the management of wire rope is used as manually operated by rope replacement from over time or after the accident.It is caused to major accidents as well as economic losses and personal injury. Therefore its time to need periodic fault diagnosis of wire rope or supply of real-time monitoring system. Currently, there are several methods has been reported for fault diagnosis method of the wire rope, to find out the feature point from extracting method is becoming more common compared to time wave and model-based system. This method has implemented a deterministic modeling like the observer and neural network through considering the state of the system as a deterministic signal. However, the out-put of real system has probability characteristics, and if it is used as a current method on this system, the performance will be decreased at the real time. And if the random noise is occurred from unstable measure/experiment environment in wire rope system, diagnostic criterion becomes unclear and accuracy of diagnosis becomes blurred. Thus, more sophisticated techniques are required rather than deterministic fault diagnosis algorithm. In this paper, we developed the fault diagnosis of the wire rope using probability density estimation techniques algorithm. At first, The steady-state wire rope fault signal detection is defined as the probability model through probability distribution estimate. Wire rope defects signal is detected by a hall sensor in real-time, it is estimated by proposed probability estimation algorithm. we judge whether wire rope has defection or not using the error value from comparing two probability distribution.

• Journal of Electrical Engineering and Technology
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• 제9권5호
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• pp.1471-1481
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• 2014

This paper presents the new power dissipation model of individual switching device in a high-level modular multilevel converter (MMC), which can be mostly used in voltage sourced converter (VSC) based high-voltage direct current (HVDC) system and flexible AC transmission system (FACTS). Also, the voltage balancing method based on sorting algorithm is newly proposed to advance the MMC functionalities by effectively adjusting switching variations of the sub-module (SM). The proposed power dissipation model does not fully calculate the average power dissipation for numerous switching devices in an arm module. Instead, it estimates the power dissipation of every switching element based on the inherent operational principle of SM in MMC. In other words, the power dissipation is computed in every single switching event by using the polynomial curve fitting model with minimum computational efforts and high accuracy, which are required to manage the large number of SMs. After estimating the value of power dissipation, the thermal condition of every switching element is considered in the case of external disturbance. Then, the arm modeling for high-level MMC and its control scheme is implemented with the electromagnetic transient simulation program. Finally, the case study for applying to the MMC based HVDC system is carried out to select the appropriate insulated-gate bipolar transistor (IGBT) module in a steady-state, as well as to estimate the proper thermal condition of every switching element in a transient state.

• 동의신경정신과학회지
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• 제33권4호
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• pp.389-400
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• 2022

Objectives: Depression is a highly prevalent disease, and the market for antidepressant drugs continues to grow at a steady rate. Although current antidepressants are reported to be effective, because of their low remission rate and side effects, new antidepressants are needed. The use of Banhahubak-tang (BHT) to treat the symptoms of depression is supported by experimental evidence. The proposed study will evaluate the efficacy and safety of BHT in treating depression. Methods: A randomized, waitlist-controlled, parallel clinical trial will be conducted to assess the efficacy of BHT in depression. A total of 84 participants with depression will be randomized into the intervention group or waitlist-control group at a 1:1 ratio. Patients in the intervention group will be administered BHT three times a day for four weeks and followed up for four more weeks after therapy completion. Patients in the waitlist-control group will undergo the same intervention and follow-up after a four-week waiting period. The primary outcome is change in the Korean version of the Hamilton Depression Rating Scale (K-HDRS) scores for major depressive disorders after four weeks. The secondary outcomes include scores on the K-HDRS, Korean Symptom Check List 95 (KSCL-95), Insomnia Severity Index (ISI), State-Trait Anxiety Inventory-Korean version (STAI-K), State-Trait Anger Expression Inventory-Korean version (STAXI-K), and the Instrument on Pattern Identifications for Depression and EuroQol-5 Dimension (EQ-5D). Conclusions: This trial will provide high-quality clinical evidence of the efficacy and safety of BHT in the management of depression.

• 지질공학
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• 제33권1호
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• pp.137-149
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• 2023

구조물에 작용하는 토압의 방향과 장기변위상태변화를 직관적으로 파악하기 위해 수평, 수직방향의 변위 데이터를 시그모이드 함수를 이용하여 가공하고 각각 좌표계의 한 축으로 하여 변위좌표계 시스템을 설정하였다. 이러한 변위좌표계에 변위상태(압축 또는 팽창) 구분영역과 관리단계 구분영역 설정하여 각 계측지점의 변위상태와 관리단계를 직관적으로 확인할 수 있었다. 관측점을 연속적으로 나타내어 변위경로를 나타내었으며, 변위경로를 통해 변위이력, 변위추세, 지반에 작용하는 응력방향 등을 알 수 있었다. 흙막이 가시설의 실계측데이터 분석 결과 모든 계측지점에서 응력해방 방향으로 변위가 일어났으며, 정상관리상태에 위치하였다. 또한 공간적 상관성이 높은 계측지점 간 거동은 비슷한 거동추세를 보였으며, 공간적 상관성이 낮은 계측지점 간에는 상이한 거동 추세를 보였다. 공간적으로 연속되어 분포하는 지표침하데이터를 변위좌표계를 이용하여 전조현상과 거동영역에 대한 상관성 분석을 수행하면 파괴시간, 영역 예측이 가능 할 것으로 판단된다.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2001년도 Proceedings ICPE 01 2001 International Conference on Power Electronics
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• pp.295-300
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• 2001

A variety of high voltage DC power supplies employing the high frequency inverter are difficult to achieve soft switching considering a quick response and no overshoot response under the wide load variation ranges which are used in medical-use x-ray high voltage generator from 20kV to 150kV in the output voltage and from 0.5mA to 1250mA, respectively. The authors develops soft switching high voltage DC power supply designed for x-ray power generator applications, which uses series resonant inverter circuit topology with a multistage voltage multiplier instead of a conventional high voltage diode rectifier connected to the second-side of a high-voltage transformer with a large turn ratio. A constant on-time dual mode frequency control scheme operating under a principle of zero-current soft switching commutation is described. Introducing the multistage voltage multiplier, the secondary transformer turn-numbers and stray capacitance of high-voltage transformer is effective to be greatly reduced. It is proved that the proposed high-voltage converter topology with dual mode frequency modulation mode control scheme is able to be the transient response and steady-state performance in high-voltage x-ray tube load. The effectiveness of this high voltage converter is evaluated and discussed on the basis of simulation analysis and observed data in experiment.

• 조명전기설비학회논문지
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• 제21권5호
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• pp.1-9
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• 2007

본 논문은 SynRM의 동손 및 철손을 최소화 하는 효율 최적화 제어를 제시한다. 퍼지와 신경회로망으로 구성된 적응 퍼지-신경회로망 제어기를 바탕으로 한 속도 제어기를 설계한다. 특정 전동기 토크를 발생하는 d-q축 전류 조합은 무수히 많이 존재한다. 효율 최적화 제어기의 목적은 정상상태에 확실한 동작점에서 d-q축 전류 조합을 찾는 것이다. 제시된 알고리즘은 양호한 동적 토크 제어를 유지하는 동안 속도 및 토크 변화를 감소시키기 위하여 전자기적 손실은 허용한다. HAI 제어기의 제어 성능은 다양한 동작 상태에서 평가된다. 결과 분석은 제시된 알고리즘의 타당성을 보여준다.

• 한국실내디자인학회논문집
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• 제27권3호
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• pp.126-135
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• 2018

In the 1960s, rapid urbanization and industrialization created the social atmosphere of individualism in Korea. Individualism has weakened social ties, led to the breakdown of communities, and caused various social problems. So, the paradigm is shifting to a shared society and there are moves to seek ways to solve social problems through community. As part of the initiative, the value and importance of common space in multi-unit dwelling, the typical Korean housing type, is increasing. Thus, the purpose of this study is to identify the trends of domestic research about common space, to assess the current state of domestic academic world and explore the future plans of the common space. The content analysis method was mainly used and statistics were additionally used to analyze 172 preceding research. As a result, research on common spaces showed a steady increase to the current time. And research was being diversified in the field of publishing journals, research contents, research methods and facilities. Until now, most studies have focused on improvement of plan and the quality of common space by identifying the attitude survey, space planning, and the actual situation. Thus many more studies about proper way to operate and manage common space need to be conducted. it is considered that the common space will develop more efficiently. The study is expected to be used as groundwork for the development of the common space and serve as concrete data to show future development directions.

• Journal of Chest Surgery
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• 제48권5호
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• pp.311-317
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• 2015

Background: Robotic surgery is an alternative to minimally invasive surgery. The aim of this study was to report on current trends in robotic thoracic and cardiovascular surgical techniques in Korea. Methods: Data from the National Evidence-based Healthcare Collaborating Agency (NECA) between January 2006 and June 2012 were used in this study, including a total of 932 cases of robotic surgeries reported to NECA. The annual trends in the case volume, indications for robotic surgery, and distribution by hospitals and surgeons were analyzed in this study. Results: Of the 932 cases, 591 (63%) were thoracic operations and 340 (37%) were cardiac operations. The case number increased explosively in 2007 and 2008. However, the rate of increase regained a steady state after 2011. The main indications for robotic thoracic surgery were pulmonary disease (n=271, 46%), esophageal disease (n=199, 34%), and mediastinal disease (n=117, 20%). The main indications for robotic cardiac surgery were valvular heart disease (n=228, 67%), atrial septal defect (n=79, 23%), and cardiac myxoma (n=27, 8%). Robotic thoracic and cardiovascular surgeries were performed in 19 hospitals. Three large volume hospitals performed 94% of the case volume of robotic cardiac surgery and 74% of robotic thoracic surgery. Centralization of robotic operation was significantly (p<0.0001) more common in cardiac surgery than in thoracic surgery. A total of 39 surgeons performed robotic surgeries. However, only 27% of cardiac surgeons and 23% of thoracic surgeons performed more than 10 cases of robotic surgery. Conclusion: Trend analysis of robotic and cardiovascular operations demonstrated a gradual increase in the surgical volume in Korea. Meanwhile, centralization of surgical cases toward specific surgeons in specific hospitals was observed.

• 정보관리학회지
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• 제32권3호
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• pp.199-219
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• 2015

본 연구는 2004년에서 2014년까지 11년간의 KERIS 상호대차 트랜잭션 데이터를 대상으로 서비스 현황과 기간별 변화를 분석하였다. 연구 결과 발견한 주요 사실은 다음과 같다. 첫째, 4년제 대학도서관의 신청과 제공건수 사이에는 밀접한 상관관계가 있었으며, 타 관종의 경우 거의 관련이 없게 나타났다. 둘째, 상호대차 대상 자료는 주제별로 살펴보면 사회과학 분야 및 문학 분야가 상위를 차지하고 있었다. 언어별로는 영어 자료가 절반 가까이 차지하고 있었다. 셋째, 신청건수가 제공건수보다 많은 기관이 전체 중에서 약 60%를 차지하였으나, 4년제 대학도서관의 경우는 비교적 균형을 이루고 있었다. 넷째, 2012년을 기점으로 KERIS 상호대차 서비스는 모든 면에서 지속적으로 성장하고 있음을 보여주고 있다.