• 대한전기학회:학술대회논문집
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• 대한전기학회 2004년도 추계학술대회 논문집 전력기술부문
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• pp.9-13
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• 2004

This paper proposes a modified current differential relay for Y-$\Delta$ transformer protection. The relay uses the same restraining current as a conventional relay, but the differential current is modified to compensate for the effects of the exciting current. A method to estimate the circulating component of the delta winding current is proposed. To cope with the remanent flux, before saturation, the core-loss current is calculated and used to modify the measured differential current. When the core then enters saturation, the initial value of the flux is obtained by inserting the modified differential current at the start of saturation into the magnetization cure. Thereafter, the core flux is then derived and used in conjunction with the magnetization curve to calculate the magnetizing current. A modified differential current is then derived that compensates for the core-loss and magnetizing currents. The performance of the proposed differential relay was compared against a conventional differential relay. Test results indicate that the modified relay remained stable during severe magnetic inrush and over-excitation because the exciting current was successfully compensated. The relay correctly discriminates magnetic inrush and over-excitation from an internal fault and is not affected by the level of remanent flux.

• Journal of the Korean Wood Science and Technology
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• 제45권2호
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• pp.139-146
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• 2017

This study was conducted to develop a new drying technology in order to quickly and massively dry bamboo tubes without crack and check. The bamboo tubes with the diameter of 45 mm - 68 mm had been impregnated in the solution of PEG-1000, and then were dried under room temperature and high temperature, respectively. The cracks occurred on all control specimens while no cracks were found on PEG treated specimens during drying at room temperature due to effect of PEG restraining the circumferential shrinkage of bamboo tube. But the drying period of this method was too long (200 days) compared to 10 hours of kiln drying. During fast high temperature drying, cracks occurred on all control specimens, but no cracks were found on PEG treated specimens, which could be accounted for more solidified PEG due to higher drying temperature and faster drying rate, and the tension set formed on the surface of bamboo tube in the early stage of drying owning to high drying temperature and low relative humidity. Thus, it is advised that PEG treated bamboo tube should be fast dried at high temperature in order to not only prevent crack or check in short drying period but also increase the dimensional stability of the products made of bamboo tubes.

• 한국지반공학회논문집
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• 제26권4호
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• pp.5-14
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• 2010

본 연구에서는 새로운 동상 억제제로서 폐타이어 파우더의 활용가능성을 검토하기 위해 폐타이어 분말 혼합토와 미혼합토를 대상으로 3년간 일본 토마코마이에서 야외실험 수행하였다. 야외실험 결과, 폐타이어 파우더를 20% 혼합함에 의해 현저한 동상억제 효과가 발생함을 확인하였으며, 관련 동상억제 효과를 동상량, 동상율, 열전도율, 투수성, segregation potential 이론 등을 중심으로 정량적으로 검토하였다.

• 한국지반공학회논문집
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• 제32권12호
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• pp.45-57
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• 2016

IER은 굴착 중에 안정성을 증가시키기 위해서 전면지주에 배면지주를 기울어지게 설치하고 강결시킨 구조이다. IER은 배면지주가 억지말뚝의 역할을 함으로써 전면지주에 발생하는 수평변위를 억제하는 효과가 있고, 전면지주에 작용하는 토압을 분산 시켜 구조적으로 안정한 가시설 공법이다. 본 연구에서는 사질토 지반에서 수치해석과 실내모형실험을 통해 IER의 두부를 강결과 힌지로 조건을 다르게 연결하여 IER의 역학적 특성을 확인하였다. 수치해석 결과, 최대수평변위는 두부의 연결 방법이 강결일 때 힌지일 때의 88%가 발생하고 실내모형실험 결과, 수평변위는 두부 연결 방법이 강결일 때 힌지일 때의 단지 7%만 발생하는 것으로 분석되었다. 또한, 지반의 전단변형 해석 결과 토압은 두부의 연결 방법이 강결일 때 힌지일 때의 67%만 작용하는 것으로 분석되었다.

• Asian-Australasian Journal of Animal Sciences
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• 제19권11호
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• pp.1665-1670
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• 2006

The objective of this research was to provide the characterization and method for producing anti-E. coli O157:H7 antibodies in egg-laying hens and to determine if the antibody can restrain the proliferation of E. coli O157:H7 in-vitro. Selected antigenic fractions (whole cell, outer membrane protein and lipopolysaccharide (LPS)) from E. coli O157:H7 were injected to hens in order to produce anti-E. coli O157:H7 antibodies. The immune response and the egg yolk antibodies of laying hens against the whole cell, outer membrane protein and LPS antigens were monitored by ELISA. The level of antibodies against whole cell antigen monitored through ELISA sharply increased after the initial immunization, and it was found to be maximum on day 49 however, the level was maintained up to day 70. Antibodies (5 mg/ml) directed against the whole cell inhibited E. coli proliferation 10-13 times more than outer membrane protein or LPS. The antibody response against the whole cell antigens appeared to have higher activity in restraining the proliferation of E. coli O157:H7 than antibody against outer membrane protein or LPS. Results reflected that increasing the IgY's in the egg yolk could prevent greater economic losses due to human and animal health from pathogenic bacteria i.e. E. coli O157:H7.

• Journal of Power Electronics
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• 제15권5호
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• pp.1305-1317
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• 2015

Distributed generation systems (DGSs) have been getting more and more attention in terms of renewable energy use and new generation technologies in the past decades. The self-excited induction generator (SEIG) occupies an important role in the area of energy conversion due to its low cost, robustness and simple control. Unlike synchronous generators, the SEIG has to absorb capacitive reactive power from the outer device aiming to stabilize the terminal voltage at load changes. This paper presents a novel static VAR compensator (SVC) called a magnetic energy recovery switch (MERS) to serve as a voltage controller in SEIG powered DGSs. In addition, many small scale SEIGs, instead of a single large one, are applied and devoted to promote the generation efficiency. To begin with, an expandable mathematic model based on a d-q equivalent circuit is created for parallel SEIGs. The control method of the MERS is further improved with the objective of broadening its operating range and restraining current harmonics by parameter optimization. A hybrid control strategy is developed by taking both of the stand-alone and grid-connected modes into consideration. Then simulation and experiments are carried out in the case of single and double SEIG(s) generation. Finally, the measurement results verify that the proposed DGS with SVC-MERS achieves a better stability and higher feasibility. The major advantages of the mentioned variable reactive power supplier, when compared to the STATCOM, include the adoption of a small DC capacitor, line frequency switching, simple control and less loss.

• Earthquakes and Structures
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• 제5권5호
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• pp.499-526
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• 2013

Seismic isolation is an effective method for the protection of buildings and their contents during strong earthquakes. This research work aims to assess the appropriateness of the linear and nonlinear models that can be used in the analysis of typical low-rise base isolated steel buildings, taking into account the inherent nonlinearities of the isolation system as well as the potential nonlinearities of the superstructure in case of strong ground motions. The accuracy of the linearization of the isolator properties according to Eurocode 8 is evaluated comparatively with the corresponding response that can be obtained through the nonlinear hysteretic Bouc-Wen constitutive model. The suitability of the linearized model in the determination of the size of the required seismic gap is assessed, under various earthquake intensities, considering relevant methods that are provided by building codes. Furthermore, the validity of the common assumption of elastic behavior for the superstructure is explored and the alteration of the structural response due to the inelastic deformations of the superstructure as a consequence of potential collision to the restraining moat wall is studied. The usage of a nonlinear model for the isolation system is found to be necessary in order to achieve a sufficiently accurate assessment of the structural response and a reliable estimation of the required width of the provided seismic gap. Moreover, the simulations reveal that the superstructure's inelasticity should be taken into account, especially if the response of the structure under high magnitude earthquakes is investigated. The consideration of the inelasticity of the superstructure is also recommended in studies of structural collision of seismically isolated structures to the surrounding moat wall, since it affects the response.

• 동의생리병리학회지
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• 제26권4호
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• pp.432-436
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• 2012

Among a number of factors related to the effect of acupuncture and moxibustion treatment, prescriptions do important work. Traditional eastern doctors also placed emphasis on prescriptions of acupuncture and moxibustion, and a lot of experiences have been accumulated. The method forms prescriptions of Sa-am acupuncture therapy pivots on five transport points. Studies show prescriptions are made on the basis of the theory of 'Wang Xiang Xiu Qiu Si'(旺相休囚死) used engendering and restraining of five phases, and it is considered the principle of transformed prescriptions through this theory. Because there is still no study analyzing prescriptions of Sa-am acupuncture by existing principles, we report opinion about Combination principle of points in them. 1. We studied history of acupuncture and moxibustion, development and kinds of points' Combination principle. 2. Around Combination principles of points in Classic of Difficult Issues and Internal Classic, we analyzed and compared between Combination principles of points in Sa-am acupuncture therapy and them in Korea and overall acupuncture methods. 1. There were many Combination principles of acupunture point combination in Classic of Difficult Issues, Internal Classic and Korea acupuncture methods. For example, Point combination of the same meridian, Point combination of the different meridian, Exterior-Interior point combination, Point combination of the same name meridian, Point combination of the multiple meridian, Point combination of Adjacent and Distant points, Left-Right point combination, Anterior-Posterior point combination, Superior-Inferior point combination, Brook point and Stream point combination, Triple energizer point combination, Eight meeting point combination, Five transport point combination, Source-Connecting point combination, Alram point and Transport point combination, Mother-Sun meridian combination, Empirical point combination, Important point combination, Point combination according to syndrome. 2. Existing Combination principles of points in prescriptions of Sa-am acupuncture therapy included every rule. 3. They could be evidences that prescriptions of Sa-am acupuncture therapy are forms inheriting and developing acupuncture and moxibustion treatments.

• 한국산학기술학회논문지
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• 제18권10호
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• pp.513-523
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• 2017

구강보건 관련 취약계층에 해당하는 거주 장애인의 개인위생과 구강위생 업무수행의 어려움의 정도 및 구강보건 수행환경을 알아보고자, 경기도 장애복지 시설 생활재활교사에게 설문조사를 실시하여 총 111부를 기술통계와 상관분석으로 분석한 결과는 다음과 같다. 첫째, 거주 장애인의 개인위생은 자발적인 칫솔질, 칫솔질 중요도 인식, 자신의 칫솔 찾기와는 정적 상관을 보였다. 둘째 거주 장애인의 구강위생 수행과 관련한 어려움의 정도는 자신의 칫솔 찾기, 치과 의료기관의 구강검사 여부에서 보통이상을 수행할 수 있는 것으로 나타났고, 자발적 수행정도에서는 잇몸 맛사지, 설탕 함유 식품 자제순으로 잘하지 못하는 것으로 나타났다. 셋째, 자발적인 칫솔질을 잘 수행할수록 올바른 칫솔질 방법 등에 대한 교육을 적절하게 받고 있는 것으로 나타났으며, 3분 이상 칫솔질과 회전법 칫솔질을 스스로 잘 수행 할수록 구강관리용품을 적절하게 지원받고 있는 것으로 나타났다. 또한 혀 닦기를 잘 수행할수록 담당 장애인의 수는 적절한 것으로 나타났다. 따라서 거주 장애인이 개인위생을 실천하기 어려운 경우, 구강위생 실천에 도움을 줄 수 있는 생활재활교사 및 장애인에게 지속적인 치위생 중재 프로그램이 필요할 것으로 보인다.

• 대한간호학회지
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• 제37권5호
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• pp.665-675
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• 2007

Purpose: The purpose of this study was to explore the experiences of people with chronic hepatitis B (CHB) in Korea. The specific aim was to identify major problems that people with CHB face and strategies that they are dealing with. Methods: A grounded theory method was utilized. The data were collected by individual in-depth interviews from 12 CHB patients from one of the major hospitals in Korea. Results: After constant comparative analysis, a core category emerged as "illness management with self-reliance and will." Seven major strategies that were identified in dealing with the illness were maintaining receptive and positive attitudes; restraining excessive work and greed; searching for information; controlling illness information; adhering to practices for not spreading the viral disease; abstaining from alcohol and smoking and maintaining healthy eating habits; nd using alternative therapies. The outcomes that result from employing these strategies were identified as burden, depression and helplessness, stress for maintaining compliance, and dispirited interpersonal relationships. Conclusion: The results of this study suggest that most people with CHB in Korea have problems in psychosocial area. Thus health professionals need to provide not only informational support but also emotional one to improve quality of life of the people with CHB.