• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1999.05a
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• pp.21-25
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• 1999

In order to remove minority carries of the base region at changing signal in conventional bipolar logic circuit, we made transistor which is composed of NPN transistor shortened buried layer under the Base region, PNP transistor which is merged in base, epi layer and substrate. Also the Ring-Oscillator for measuring transmission time-delay per gate was designed as well. In the result, we get amplitude of logic voltage of 200mV, the minimum of transmission delay-time of 211nS, and the minimum of transmission delay-time per gate of 7.26ns in AC characteristic output of Ring-Oscillator connected Gate.

• Electrical & Electronic Materials
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• v.7 no.4
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• pp.294-299
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• 1994

CHF$_{3}$/CH$_{4}$Ar 플라즈마에 의해 형성된 산화막 식각 잔류물의 화학구조와 이 잔류물의 제거를 위한 세정방법을 x-ray photoelectron spectroscopy를 이용하여 조사하였다. 잔류무르이 구조는 CF$_{x}$-polymer와 Si-C, Si-O 결합으로 이루어진 SiO$_{y}$ C$_{z}$ 이었다. CF$_{4}$O$_{2}$ 플라즈마에 의한 silicon light etch는 산화막 식각 잔류물인 SiO$_{y}$ C$_{z}$ 층과 손상된 실리콘 표면을 제거하엿으며 NH$_{4}$OH-H$_{2}$O$_{2}$과 HF용액으로 완전히 제거되는 CF$_{x}$-polymer/SiO$_{x}$층을 남겼다. 100.angs.정도의 silicon light etch는 minority carrier life time과 thermal wave signal값을 초기 웨이퍼 수준까지 회복시켰으며 접합누설 전류도 거의 습식 식각 공정수준까지 감소시켰다.

• The Journal of Natural Sciences
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• v.4
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• pp.233-244
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• 1991

This study was counducted to identify a relationship between the aesthetic costume arising from an and-social minority movement towards the end of 19c, England on the one hand, and bustle and crinolette style which were in fashion at that time, on the other. The aesthetic comstume is studied with articles and cricatures in the magazien "Punch" which was famous for its harsh criticisms of society. Aesthetic elements from various sources were praised or sometimes cricatured by Punch. Aesthets pursued naturalness as is found in Greek costume in reaction to the gross modernised Victorian costume. To be specific, the aesthetes pursued 1)loose robe instead of corset with bustle or crinolette, 2)2nd/3rd dimentionally-coloured dyes instead of anyline in the costume. Liberty Department Store in London has planyed a very important role as a major supplier or aesthteic articles to the aesthetes.

• International Journal of Advanced Culture Technology
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• v.7 no.4
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• pp.222-228
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• 2019

In recent years, in order to enhance the problem-solving skills required by the industrial field, universities have introduced the Problem-Based Learning(PBL) method to solve the problems caused by the lack of creativity, problem solving ability and self-directed learning. This study applied PBL class methods such as 'learning based on individual specific problems', 'self-directed learning', and 'small-group learning of small members' to practical design of fashion design. To do this, I conducted a questionnaire after conducting research based on the PBL module for one semester in a practical class of fashion design major at P University. As a result of the survey, the satisfaction and achievement of the class conducted by PBL learning method was improved than the existing teaching method. As such, if PBL class is used as a way of solving problems through close communication between professors and learners, it is expected to be established as a learner-centered education method that can improve creativity and professionalism.

• Korean Journal of Childcare and Education
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• v.14 no.5
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• pp.85-99
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• 2018

Objective: This purpose of this study was to analyze articles and research trends in children's free-choice activities in major domestic journals published from 1998 to 2017. Methods: Registered research papers in academic journals from 1998 to 2017 for the National Research Foundation of Korea were analyzed in terms of trends in their annual submission numbers, research subject, research type, research area. and research theme. Results: The quantity of the studies has more than doubled since 2010 but has decreased in recent years. Studies about free-choice activities for young children held the majority of research subjects while physical subjects such as literature, class, and education plans were in the minority. Furthermore, qualitative research, fusion qualitative, and survey were the most common research types while literature review studies were less common. Most research themes were studies about contemplation, actual conditions and perception, factor analysis, and programs of free-choice activities for young children. Conclusion/Implications: Considering the results of this study, further studies on free-choice activities for young children must be conducted.

• Journal of the Semiconductor & Display Technology
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• v.19 no.2
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• pp.68-71
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• 2020

In this study, SiNx and Al₂O₃ thin film was manufactured using PECVD deposition process and applied to crystalline silicon solar cells, resulting in 16.7% conversion efficiency. The structural improvement experiment of the rear electrode resulted in a 1.7% improvement in conversion efficiency compared to the reference cell by reducing the recombination rate of minority carriers and increasing the carrier lifetime by forming a passivation layer consisting of SiNx and Al₂O₃ thin films through the PECVD process.

• The Transactions of the Korean Institute of Electrical Engineers B
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• v.49 no.3
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• pp.188-194
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• 2000

This paper presents new Zero-Voltage-/Zero-Current-Switching (ZVZCS) PWM DC-DC converters. The proposed soft-switching technique achieves ZVS and ZCS simultaneously at both turn-on and turn-off of the main switch and diode by using only one auxiliary switch. Also, the proposed soft-switching technique is suitable for not only minority but also majority carrier semiconductor devices. The auxiliary circuit of the proposed topology is placed out the main power path and therefore, there are no voltage/current stresses on the main switch and diode. The operating principle of the proposed topology is illustrated by a detailed study with a boost converter as an example. Theoretical analysis, simulation and experimental results are presented to explain the proposed schemes.

• KIEE International Transaction on Electrical Machinery and Energy Conversion Systems
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• v.2B no.4
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• pp.183-190
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• 2002

This paper presents an improved Zero Voltage/Zero Current Switching (ZVZCS) commutation cell with minimum additional components, which provides soft switching at both turn-on and turn-off of main and auxiliary switches as well as diodes in a PWM DC/DC converter. The proposed soft-switching technique is suitable for not only minority, but also majority carrier semiconductor devices. The auxiliary switch of the proposed ZVZCS commutation cell is in parallel with the main switch, and therefore, the main switch and the diode are free of currentstress. The operation principles of the proposed ZVZCS commutation cell are theoretically analyzed using the PWM boost converter topology as an example. The validity of the PWM boost converter topology with the proposed ZVZCS commutation cell is verified through theoretical analysis, simulation and experimental results.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.13 no.2
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• pp.120-124
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• 2000

In this paper, the effects of trap distribution on switching characteristis of a lateral insulated gate bipolar transistor (LIGBT) are investigated. The simulations are performed in order to to analyze the effect of the positon, width and concentration of trap distribution model with a reduced minority carrier lifetime using 2D device simulator MEDICI. The turn off time for the proposed LIGBT model A with the trap injection is 0.8$mutextrm{s}$. These results indicate the improvement of about 2 times compared with the conventional LIGBT. It is shown that the trap distribution model is very effective to reduce the turn-off time with a little increasing of on-state voltage drop.

• Proceedings of the KIEE Conference
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• 2003.07c
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• pp.1556-1558
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• 2003

IGCT devices is a superior devices for power conversion purpose. The basic structure of the IGCT devices is same as that of GTO thyristor. This makes the blocking voltage higher and controllable on-state current higher. In this paper, we present static and dynamic characteristics of 4.5 kV PT-type IGCT devices as a function of minority carrier lifetime, n-base thickness and n-buffer thickness. We should choose proper structural parameters for good electrical characteristics of GCT devices.