• 전기의세계
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• 제31권1호
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• pp.50-58
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• 1982

As a method for improving the power factor and the waveform of ac line current drawn by ac to dc converters, converters of pulse-width control type with forced commutation circuits have been developed in recent years. However, these converters have rather complex commutation circuits which contain auxiliary thyristors in addition to the main thyristors, and their performance is not satisfactory. This paper proposes a new pulse-width controlled ac to dc converter, and analyses its commutation mechanism and its input and output characteristics. The proposed converter circuit consists of a usual thyristor bridge circuit with series diodes to which reactors and diodes are added. This circuit dose not contain auxiliary thyristors, and in this sense it is simpler than the previous converter circuits of pulse-width control type. Since the main thyristors of the converter can be forcedly turned off several times in a half cycle of source voltage, a pulse-width modulation control is possible in order to improve the current waveform as well as the power factor on ac line side. As to dc output side it is shown that the adjustable range of output voltage is wide and the voltage regulation is good due to a rapid reversal of voltage across the commutating capacitors by LC resonance during commutation period. It is also shown that the regenerative operation of the converter is possible.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2002년도 제4회 영호남학술대회 논문집
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• pp.73-79
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• 2002

This study evaporates ZnO layer thickness' differently with RF sputtering method on Si Wafer(n-100). This study is performed to examine the characteristics of photon energy and dielectric loss according to the thickness of ZnO and increase the reliability and reproduction of ZnO thin film. It is confirmed that the variation of electric Permittivity by frequency is resulted from the formation of particles within thin film, the particle size and the polarization on grain boundary. Peak of electric Permittivity value of thin film has slower and less value in early low wavelength by the coulomb force involved in carrier combination according to the increase of frequency. Reversal of electric Permittivity values is induced by dipole polarization shown in the dielectric of thin film. Complex electric constant $({\varepsilon}_1,{\varepsilon}_2)$ has larger peak values as it's thickness is thinner and then it is larger according to the increase of frequency. Electric Permittivity by photon energy has large value in imaginary number and is reduced exponentially by the increase of carrier density according to that of photon energy.

• 한국음향학회지
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• 제38권5호
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• pp.587-592
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• 2019

수중음향통신에서 다중경로로 인한 인접 심볼 간 간섭은 통신 성능을 저하시킨다. 인접 심볼 간 간섭의 영향을 최소화하여 수중음향통신 성능을 향상시키기 위해 다이버시티 기법을 사용한다. 본 논문에서는 공간 다이버시티와 시간 다이버시티의 결합을 통해 수중음향통신 성능이 개선됨을 보인다. 시공간 다이버시티를 통해 제한적인 배열에서 수중통신 시스템의 효율성을 증대시켰다. 또한 2018년 10월 한국의 동쪽 해역에서 수행한 BLAC18(Biomimetic Long range Acoustic Communication 18) 실험 데이터와 비교하여 이를 검증하였다.

• 패션비즈니스
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• 제23권3호
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• pp.1-9
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• 2019

The purpose of this study was to develop questions for fashion design development, by applying 7 elements of the scamper to the fashion design elements, and to present a scamper checklist of fashion design elements, and item structures. In this study, the scope of research was limited to clothing design among various fashion products, and among various design development stages. Fashion design development focusing on design sketching, was limited to the research scope. The research method was based on an empirical study that derived scamper questions through FGI (Focus Group Interview), consisting of 5 fashion experts. Fashion design elements applied to development of scamper questions consisted of silhouettes, constructive lines, structural details, decorative details, patterns and textures of fabrics, and item structures, derived by applying these elements to the individual 7 elements of the scamper: substitute, combine, adjust, modify, put to other uses, eliminate, and reverse. Results of the study included 7 questions for substituting, 8 questions for combining, 6 questions for applying, 15 questions for modifying, 4 questions for putting to other uses, 4 questions for eliminating, and 7 questions for reversal. The scamper checklist for fashion design elements and item structures drew to 5 lists of silhouette variations, 7 lists of constructive line variations, 11 lists of structural detail variations, 10 lists of decorative detail variations, 11 lists of fabric variations, and 9 lists of structural modifications of items.

• International Journal of Naval Architecture and Ocean Engineering
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• 제13권1호
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• pp.617-627
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• 2021

Underwater Acoustic Channels (UAC) have inherent sparse characteristics. The traditional adaptive equalization techniques do not utilize this feature to improve the performance. In this paper we consider the Variable Adaptive Subgradient Projection (V-ASPM) method to derive a new sparse equalization algorithm based on the Minimum Symbol Error Rate (MSER) criterion. Compared with the original MSER algorithm, our proposed scheme adds sparse matrix to the iterative formula, which can assign independent step-sizes to the equalizer taps. How to obtain such proper sparse matrix is also analyzed. On this basis, the selection scheme of the sparse matrix is obtained by combining the variable step-sizes and equalizer sparsity measure. We call the new algorithm Sparse-Control Proportional-MSER (SC-PMSER) equalizer. Finally, the proposed SC-PMSER equalizer is embedded into a turbo receiver, which perform turbo decoding, Digital Phase-Locked Loop (DPLL), time-reversal receiving and multi-reception diversity. Simulation and real-field experimental results show that the proposed algorithm has better performance in convergence speed and Bit Error Rate (BER).

• Nuclear Engineering and Technology
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• 제16권2호
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• pp.47-57
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• 1984

2상유동을 해석하기 위한 3차원 코드인 THERMIT-6S의 미분 방정식을 세우기 위해, 수학적으로 정확하게 유도된 시간과 공간에 대해 평균한 보존 방정식을 단순화했다. 미분 방정식을 불연속화(discretization)하여 THERMIT-6S의 차분방정식을 얻는다. First-order spatial scheme, donor cell method, 그리고, staggered mesh layout을 써서 공간에 대한 불연속화를 한다. 그리고 시간에 대한 불연속화는 first-order semi-implicit scheme으로써, sonic terms와 국부적인 전달 현상에 관계되는 항들은 implicit하게 그리고 대류 전달 항들은 explicit하게 취급한다. 이렇게 얻어진 방정식들은Newton-Raphson 방법으로 선형화된다. 축소된 압력 방정식을 만들기 위해 모든 변수들이 mesh cells사이에서 단지 압력 변수를 통해서만 결부되도록, 선형화된 방정식들을 처리한다. OPERA-15 실험을 수치해석적으로 모의실험하여 본 결과, THERMIT-6S가 flow coastdown, 역류, 유체진동(flow oscillation) 등을 포함하고, sodium boiling 후의 원자로내의 변화를 예측하는데 매우 유효하다는 것이 밝혀졌다.

• Archives of Plastic Surgery
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• 제36권2호
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• pp.183-187
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• 2009

Purpose: Because of the volume of elective sterilizations performed in the world during the past decade, the vasectomy was a popular method for male sterilization in Korea and this, in turn, had been followed by an increase in the number of patient requiring vasectomy reversal with the high rate of subsequent divorce and remarriage. Recently, many authors have reported high success rates of vasovasostomy using microsurgical techniques and we performed modified two layer vasovasostomy with intravasal silicone tube to increase postoperative patency and pregnacy rate. Methods: Microscopic vasovasostomy was performed in 9 patients and their average age was $35.78{\pm}1.36years$(from 28 years to 44 years) from June 2006 to June 2008 at our department using modified two layer vasovasostomy with silicone tube insertion. Standard Guibor silicone tube, consisting of two 17.7 cm, 0.064 cm diameter, malleable, stainless steel probes connected by 29 cm of silicone tubing wedged onto disposable probes, were used in all cases. Results: Success rates were 88.8 % for patency and pregnancy 44.4 % for pregnancy in modified two layer vasovasostomy with silicone tube insertion. The patency rates were higher in cases of long postoperative day and in cases of short duration of vasectomy and vasovasostomy. Conclusion: We used a modified method to correspond the patency and pregnancy rate in microscopical modified two layer vasovasostomy using the intravasal silicone tube permanently. This method brings normal patency in microsurgical vasovasostomy because the silicone tube prevent obstruction of anastomosed site of the vas permanently.

• 한국실내디자인학회논문집
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• 제18권6호
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• pp.44-51
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• 2009

Various and complex cultural phenomena have led to many changes in the space. The concept of unconsciousness, among others, and experimental expression technique and the concepts from surrealism that rather attaches great importance to contingency than intentional attempt have been employed in the space. The abstract expression as expressional characteristics of surrealism makes the space ambiguous through the concept of automatism using the approach of indeterminism and double image expression, and represents the space providing diversity through the dualism. In contrast, objective expression, which was based on depaysement, generates the tension and expresses the dramatic situation in such a way and manner which are intentional, distorted transformed, together with heterogenous meanings aligned through the reversal appeared in the techniques of collage and paranoiac-critical method. However if such space accommodating the expressional characteristics of surrealism is approached as superficial concept in analyzing the human's inner consciousness and imaginary society, expression of the ultimate concept contained in the expressional characteristics of surrealism can hardly be achieved. Hence, the spatial analysis from the semiotic approach, instead of unilateral method aimed to convey the meaning only, which creates the signification, was adopted. The study, as effective approach to the space accommodating the expressional characteristics of surrealism, was intended systematically evaluate the concreteness of understanding and generation of meaning through the semiotic method. Greimas' semiotic square analysis to the space plays the important role in generating the spatial meaning, as well as is needed for objective analysis of the importance of various characteristics and methodology which the space contains through the expressional characteristics of surrealism.

• Clinical and Experimental Reproductive Medicine
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• 제23권1호
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• pp.61-66
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• 1996

Vasectomy has become a popular method for male sterilization and this, in tum, has been followed by an increase in the number of patients requiring vasectomy reversal. Recently, many authors have reported a high success rate of vasovasostomy using microsurgical techniques. However, a significant discrepancy exist between the anatomical patency rate and pregnancy rate despite improvements in surgical techniques. Number of 420 patients who underwent vasovasostomy by a modified one layer reanastomosis from January 1986 to December 1994 were reviewed. Of the total, Complete follow up were possible in 115 patients. Of the 115 patients, 74 patients were treated by macroscopic reanastomosis, and microscopic technique were applied in 41 patients. Duration of vasal obstruction, gross apperance of vasal fluid, operative method, presence or absence of sperm and sperm granuloma, and results of postoperative semen analysis were analyzed as factors influencing the pregnancy rate. Success rates for patency and for pregnancy were 81% and, 42% respectively. Rate of pregnancy were increased if there were shorter periods of obstruction(<10years), bilateral observation of watery vasal fluid, presence of sperm bilaterally, bilateral presence of sperm granuloma at the vasectomy site, and normal results on postoperative semenalysis. With these results, we can conclude that all factors mentioned may affect the success rate of pregnancy following vasovasostomy.

• 복식
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• 제63권7호
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• pp.65-78
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• 2013

This study aims to suggest the methodology for conservation of excavated costumes especially repair and restoration process. Early excavated costumes had not attracted attention from the field of academia and the public. So not many scholars, organization and society participated in the excavations but as its value has gotten more recognition, there has been a reversal in trend. And so many organizations have taken part in it. Excavating includes conservation processes such as washing, repair and restoring, and then it is published by reports or books after the process is complete. However the method of conservation has varied depending on the institution. In particular, repair and restore methods do not include anything specific details, and often times, only has descriptions of the before and after state, and so a more unified method needs to be suggested and shared. This study defined 'Conservation', 'Repair' and 'Restoration' and then applied it to the short history of Korean excavated-costumes. Then it suggested ways to repair and restore excavated-costumes in terms of construction, textile, and damage by the unpublished cases of excavated-costumes of Noh Su-ham(1516~1573)'s Family. It was also referred to repair and restoration process such as shaping correction, dyeing, supporting, sewing and after treatment by texts and pictures. Other contents such as a list of relics and its details, will be published through a report or a book. The whole process of conservation was in progress based on the ethical guidelines of conservation, 'Minimum intervention' and 'Reversibility'.