• ETRI Journal
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• v.34 no.6
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• pp.816-826
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• 2012

Self-healing Ethernet rings show promise for realizing the SONET/SDH-grade resilience in Carrier Ethernet infrastructures. However, when a ring is faulty, high-priority protection messages are processed in less time than low-priority data frames are processed. In this situation, any delayed data frames either being queued or traveling through long ring spans will cause the ring nodes to generate incorrect forwarding information. As a result, the data frames spread in the wrong direction, causing the ring to become unstable. To solve this problem, we propose four schemes, that is, dual flush, flush delay timer setting, purge triggering, and priority setting, and evaluate their protection performance under various traffic conditions on a ring based on the Ethernet ring protection (ERP) method. In addition, we develop an absorbing Markov chain model of the ERP protocol to observe how traffic congestion can impact the protection performance of the proposed priority setting scheme. Based on our observations, we propose a more reliable priority setting scheme, which guarantees faultless protection, even in a congested ring.

• ETRI Journal
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• v.32 no.2
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• pp.184-194
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• 2010

Ethernet ring protection (ERP) technology, which is defined in ITU-T Recommendation G.8032, has been developed to provide carrier grade recovery for Ethernet ring networks. However, the filtering database (FDB) flush method adopted in the current ERP standard has the drawback of introducing a large amount of transient traffic overshoot caused by flooded Ethernet frames right after protection switching. This traffic overshooting is especially critical when a ring provides services to a large number of clients. According to our experimental results, the traditional FDB flush requires a link capacity about sixteen times greater than the steady state traffic bandwidth. This paper introduces four flush optimization schemes to resolve this issue and investigates how the proposed schemes deal with the transient traffic overshoot on a multi-ring network under failure conditions. With a network simulator, we evaluate the performance of the proposed schemes and compare them to the conventional FDB flush scheme. Among the proposed methods, the extended FDB advertisement method shows the fastest and most stable protection switching performance.

• Journal of the Korean Ceramic Society
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• v.49 no.6
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• pp.637-641
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• 2012

Due to its high production cost and relatively high energy consumption during the Siemens process, poly-silicon makers have been continuously and eagerly sought another silicon route for decades. One candidate that consumes less energy and has a simpler acidic and metallurgical purification procedure is upgraded metallurgical-grade (UMG) silicon. Owing to its low purity, UMG silicon often requires special steps to minimize the impurity effects and to remove or segregate the metal atoms in the bulk and to remove interfacial defects such as precipitates and grain boundaries. A process often called the 'gettering process' is used with phosphorus diffusion in this experiment in an effort to improve the performance of silicon solar cells using UMG silicon. The phosphorous gettering processes were optimized and compared to the standard POCl process so as to increase the minority carrier lifetime(MCLT) with the duration time and temperature as variables. In order to analyze the metal impurity concentration and distribution, secondary ion mass spectroscopy (SIMS) was utilized before and after the phosphorous gettering process.

• 대한공업교육학회지
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• v.44 no.1
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• pp.209-231
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• 2019

The purpose of this study was to extract the factors of core competency required for technology teachers and to analyze the educational needs for extracted core competency factors and to search for the application of core competencies in the in-service technology teachers education. This study was conducted by literature review, expert validation, and needs assessment method. The survey was conducted by 92 low-carrier technology teachers who participated in in-service technology teachers education for upgrading to first grade teacher certificate. Data were analyzed the factor analysis, needs assessment, and IPA analysis using SPSS 24. The core competencies with high education needs were selected by the score of the Borich formula and the IPA analysis. As a result of the study, 29 factors of core competencies were chosen as the priority: challenge, planning ability, decision making ability, future orientation, intellectual property utilization ability, communication ability, and creative thinking etc. Based on the conclusions of this study, I would suggest the following. It is to create a new in-service education program reflected on core competencies that have high educational needs of low-carrier technology teachers. In addition, a strategy that reflects core competencies methodically in existing in-service teachers education program is needed. Future research should be followed by research on curriculum design to enhance high needed core competencies of low-carrier technology teachers.

• The Research Journal of the Costume Culture
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• v.4 no.3
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• pp.337-347
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• 1996

The work-man's Uniform should be coincident with the image of his firm and accounted of the function according s its purpose. We made questions to 404 workers at 8firm in our country through the questionnaire papers to know about a work-man's uniform and researched whether the satisfactory in wearing his uniform had relation with his type of business, grade, carrier, age, marriage, and monthly income. The results of this study is as follows; 1. In the case of wearing the uniform many workers answered they always wore their uniform in the firm. It was shown that the office workers wore their uniform much more than workers in the production department. The longer the time working, the older age, the lower grade of school career are, he more workers wear. the order of the importance for he uniform was the function, the symbol, the originality, and the fashion. The longer their career in the firm was, the more important the function of their uniform was. 2. The order of dirty pat in taking care of the uniform was cuffs, color, the front of part in an upper garment and below the knee, the hip in pants It was very easy for the workers in the experts, or administrators and office workers than others to be dirty in the cuffs part of the uniform. Worn part of the uniform showed highest cuffs in an upper garment and a zipper in pants. The order of cleaning the uniform was washing by water, no ironing, and cleaning in their house.

• 한국신재생에너지학회:학술대회논문집
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• 2009.06a
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• pp.745-748
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• 2009

수소는 지구상에 풍부하게 존재하는 원소로 최근 수소경제시대에 대한 기대와 함께 청정 에너지 carrier로 주목받고 있다. 본 연구에서는 고순도 수소 생산을 위해 water gas shift (WGS) 반응과 $CO_2$의 분리를 하나의 unit operation의 형태로 수행하는 신개념의 thermal swing sorption enhanced reaction (TSSER) 공정의 타당성을 테스트하는데 목적을 두고 있다. Le Chatelier 원리를 기본으로 하는 흡착분리 동시 반응 (sorption enhanced reaction, SER)에서는 수소생산 반응의 열역학적 한계를 극복할 수 있고 정반응의 속도를 증대시킬 수 있다. 본 연구에서는 $K_2CO_3$가 첨가된 hydrotalcite에 대한 고온에서의 $CO_2$ 화학흡착 평형 및 거동 데이터를 실험을 통하여 측정하였다. 또한 WGS 상용촉매와 화학 흡착제를 이용하여 흡착분리 동시 반응을 실험과 수치해석 시뮬레이션으로 수행하였고, 연구결과로부터 연료전지에 사용할 수 있는 고순도의 수소 (~10 ppm CO)를 직접 생산할 수 있으며, 동시에 고압상태의 $CO_2$를 고순도로 포집할 수 있음을 확인할 수 있었다. 고압, 고순도의 $CO_2$ 포집은 이후 $CO_2$ 저장에 용이하게 이용되어 온실가스 저감에 기여할 수 있을 것으로 기대된다.

• Journal of Korea Foundry Society
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• v.14 no.1
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• pp.28-34
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• 1994

Metallurgical-grade polycrystalline silicon was directionally solidified at growth rates of $0.2{\sim}1.0mm/min$ by using split type, reusable graphite molds which were coated with $Si_3N_4$ powder. The resultant grain sizes of the silicon ingots and the shapes of the solid/liquid(S/L) interfaces were investigated. X-ray diffraction was used to determine the preferred orientation in each of the silicon ingots. The impurity content of the silicon was analyzed and the resistivities of the ingots were measured. During the growth of an ingot, the shape of the S/L interface was concave to the silicon melt, and the resistivity decreased. The presence of Al which can be acting as a carrier, is thought to be the main factor causing such a decrease in resistivity. When a growth rate of 0.2㎜/min was used, the preferred orientation was found to be (111).

• Electronics and Telecommunications Trends
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• v.28 no.6
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• pp.13-27
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• 2013

SDN(Software Defined Network) 기술이 미국을 중심으로 먼저 출발하였으며 NFV(Network Function Virtualization) 기술은 유럽을 중심으로 한 SDN의 경쟁적인 기술로 초기에는 인식이 되었으나, 두 기술의 상호 시너지 효과를 고려하여 2013년 하반기부터는 다양한 형태의 협력 방안들이 표준단체, 산업체 및 캐리어들로부터 소개되고 있다. 두 기술이 지향하는 가장 큰 목표는 하드웨어의 의존성을 배제하고 네트워크 및 서비스를 추상화함으로써 캐리어들이 신규 서비스를 Time-to-Market에 맞게 그러면서도 유연하게 출시하고 제어 및 관리를 중앙집중 방식으로 제공하여 CAPEX(Capital Expenditure) & OPEX(Operating Expense)를 최소화 하는데 있다. 본고에서는 이 두 기술의 표준화 및 기술 동향, 그리고 아직은 태동기인 두 기술이 지향하는 다양한 Use Case들과 적용사례를 캐리어 환경 중심으로 살펴보고 향후 상용화 및 산업화에 대한 장 단기 발전 전망에 대해 기술 중심으로 예측해 본다.

• Textile Coloration and Finishing
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• v.32 no.3
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• pp.128-134
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• 2020

Heat and flame protecting cloth is usually made of meta aramid fiber because of its own properties. But the high inter molecular hydrogen bonding and high Tg is the reason of the difficulty to dye meta aramid fiber. Recently, it was commercialized that the easily dyeable meta aramid fiber(AMD) for improving dyeability. In this study, the dyeing properties of AMD dyed with cationic dyes were investigated. The K/S values of AMD were 5~10% higher than these of general meta aramid fiber(AM) in the case of 1%owf caused by the lower crystallinity of AMD. The difference between K/S values of AMD and AM was increased as increasing dyeing concentration. The washing and rubbing fastness grade of AM and AMD were similar and good to very good.

• Proceedings of the KAIS Fall Conference
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• 2011.12a
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• pp.330-333
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• 2011

Allomatrix (Wright Medical Tech, Inc., USA), is a newly designed, injectable putty with a reliable demineralized bone matrix(DBM), derived from human bone. The compound contains 86% DBM and other bone growth factors such as bone morphogenic protein (BMP)-2, BMP-4, insulin-like growth factor (IGF)-1, and transforming growth factor (TGF)-${\beta}1$. It has excellent os-teoinduction abilities. In addition, DBM is known to have osteoconduction capacity as a scaffold due to its collagen matrix. This product contains a powder, which is a mix of DBM and surgical grade calcium sulfate as a carrier. A practitioner can blend the powder with calcium sulfate solution, making a putty-type material which has the advantages of ease of handling, better fixation, and no need for a membrane, because it can function as membrane itself. This study reports the clinical and radiographic results of various guided bone regeneration cases using Allomatrix, demonstrating its strong potential as a graft material.