• Transactions of the Korean Society of Mechanical Engineers
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• v.16 no.3
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• pp.497-505
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• 1992

본 연구에서는 최근에 개발된 직물 탄소섬유강화 복합재료의 파괴인성치를 정 량적으로 결정하고 파괴거동을 조사하고자 한다. 본 연구의 목적은 이 재료에 선형 탄성파괴역학의 적용여부를 알아보고, R곡선을 이용하여 균열의 생성점 및 불안정 파 괴점의 파괴인성치를 정확히 구하며, 주사형 전자현미경을 통해 파단면 및 균열 성장 시점을 관찰하여 파괴거동을 조사하는데 있다.

• Restorative Dentistry and Endodontics
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• v.35 no.2
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• pp.134-142
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• 2010

The purpose of this study was to evaluate the effect of Er,Cr:YSGG laser irradiation with hypersensitivity mode on microtensile bond strength of composite resin. Twenty extracted permanent molars were randomly assigned to six groups, according to the irradiation of Er,Cr:YSGG laser, adhesive system (Optibond FL or Clearfil SE bond) and application time of etchant (15 sec or 20 sec). Then composite resin was build up on each conditioned surface. The restored teeth were stored in distilled water at room temperature for 24 h and twelve specimens for each group were prepared. All specimens were subjected to microtensile bond strength and the fracture modes were evaluated. Also, the prepared dentin surface and laser irradiated dentin surface were examined under SEM. The results were as follows: 1. The microtensile bond strength of laser irradiated group was lower than that of no laser irradiated group. 2. Regardless of laser irradiation, the microtensile bond strength of Optibond FL was higher than that of Clearfil SE bond. And the microtensile bond strength of 20 sec etching group was higher than that of 15 sec etching group when using Optibond FL. 3. The SEM image of laser irradiated dentin surface showed prominent peritubular dentin, opened dentinal tubules and no smear layer.

• Korean Journal of Organic Agriculture
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• v.23 no.1
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• pp.123-131
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• 2015

In this study, viral disease samples were obtained between 2006 and 2010 from pepper fields in 11 major pepper-growing districts in Gangwon-do, and in 83 areas from other provinces, with the exception of Gyeongsangnam-do and Jeju island in Korea. In order to assess the type of infection, field surveys were conducted with regard to viral disease severity and virus type, based on typical symptoms on leaves. The means of single and mixed-virus infections were 46.6% and 48.0%, respectively, during those periods, suggesting that viruses are the agents that most severely decrease pepper production in field cultivation in Korea. In terms of single infection, Cucumber mosaic virus (CMV) was the most prevalent virus based on its disease severity ratings (34.8%). Next, Pepper mild mottle virus (PMMoV) and Pepper mottle virus (PepMoV) were shown to cause severe viral diseases in pepper, with disease severities of around 5-10%. On the other hand, Tomato spotted wilt virus (TSWV) occurs in a limited area in Chungcheongnam-do and Jeollanam-do. Thus, the viral disease caused by CMV, PMMoV, and PepMoV in pepper can be severe, and these virus types should remain considered critical reasons for decreased pepper production in field cultivation in Korea. In addition to single infection, mixed infections are frequently observed in collected pepper samples from all areas. The ratios of mixed infection were therefore studied to evaluate the disease severity of mixed infections and to define individual virus types. These data showed that different types of viruses were present, and CMV was the most abundant virus for mixed infection, as in the case of single infection. Among mixed infections, the highest disease severity was seen with CMV+Broad beam wilt virus 2 (BBWV2), followed by other types of mixed infection such as CMV+PepMoV and CMV+PMMoV. However, further work is needed to reduce the severe damage caused by viruses and to assess mixed infection types involving three or more viruses.

• Proceedings of the Korean Society For Composite Materials Conference
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• 2002.10a
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• pp.252-256
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• 2002

본 연구에서는 유리섬유/나일론 6 복합재료의 계면특성에 미치는 실란계 사이징제의 영향을 조사하기 위하여 microbonding test, short-beam shear test 그리고 dynamic mechanical analysis 방법을 사용하였다. 전자의 미시적인 방법과 후자의 두 가지 거시적인 접근 방법으로부터 얻은 유리섬유/나일론 6 복합재료의 계면특성에 대한 결과가 서로 일치하였다. 상업적으로 사이징 처리된 경우와 비교할 때, 본 연구에 적용된 네 종류의 실란계 사이징제는 유리섬유-나일론 6 수지의 계면결합력을 크게 향상시켰다. 특히, 3-chloropropyltrimethoxysilane (Z-6076)의 사용은 유리섬유/나일론 6 복합재료의 계면전단강도와 층간전단강도를 가장 두드러지게 증가시켰다.

• Proceedings of the Materials Research Society of Korea Conference
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• 2012.05a
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• pp.103.2-103.2
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• 2012

알루미늄기지 복합재료는 낮은 밀도, 높은 비강도, 우수한 강성을 가지고 있어서 수송기기용 경량소재로서 적용 가능하다. 강화재를 외부에서 주입하는 ex-situ 법에 비하여 화학반응에 의하여 강화상이 생성되는 in-situ 법은 기지와 강화상의 계면 특성이 우수하다. In-situ 주조법으로 제조한 알루미늄기지 복합재료는 여러 형태로 가공하기 위하여 압출, 열간압연 등의 공정을 거치게 되므로 열간가공성에 대한 이해가 필요하다. 이 연구에서는 고온압축시험을 이용하여 in-situ $Al/TiC_p$ 복합재료의 열간가공성을 평가하였다. 고온유동곡선으로부터 변형률속도민감도를 구하였으며 Dynamic Material Model을 이용하여 efficiency of power dissipation을 표현하는 공정지도를 작성하였다. 또한 변형 조건에 따른 미세조직 발달 거동을 조사하였으며 이로부터 각 변형 구간에 대한 변형기구를 도출하였다. 이로부터 알루미늄기지 복합재료의 열간가공성에 미치는 강화상의 영향을 고찰하였다.

• Korean Journal of Materials Research
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• v.6 no.11
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• pp.1090-1098
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• 1996

개조한 가스 금속 아아크 용접공정을 이용하여 SiC/AI 금속기 복합재료를 제조하고 그 특성을 조사하였다. AI 모재위에 강화입자의 크기와 부피분율을 변화하여 다양한 SiC/AI 복합재료층을 제조하였고, 만들어진 복합재료층의 특성은 미세조직관찰과 미소경도시험을 통하여 이루어졌다. 복합재료층의 두께는 약 7-8mm로 측정되었고 균일한 강화입자의 분포도를 얻을 수 있었다. 분산입자의 부피분률은 Ar가스의 유량에 의하여 조절하였고 분산입자의 부피분률이 증가하고 크기가 작아짐에 따라 기지의 수지상 응고조직은 더욱 미세화되었다. 복합재료의 부피경도는 분산입자의 부피분률이 감소함에 따라 낮아졌으나 입자 크기에는 크게 변화가 없는 것으로 나타났다.

• The Journal of Society for e-Business Studies
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• v.18 no.4
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• pp.1-24
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• 2013

Since the introduction of e-Government in Korea, government departments and public sectors produced a diversity of electronic records. In addition, they generated new electronic records (we are called composite electronic records(CERs)) which are composed of disparate electronic records. Typical examples of CERs are the records of Social Network Services (SNS). Currently, most of the government departments in Korea uses the Facebook Page to announce their policy and to collect feedback from the people. In addition, many CERs are created and produced. However, the government of Korea has no preservation policies about CERs. It causes problems with losing or neglecting a lot of information. Therefore, we presented the type and the characteristics of CERs which are produced by government departments of Korea. Moreover, we analyze and represent the researches of CERs preservation. Finally, we proposed the mechanism to preserve of CERs in Korea.

• The Journal of the Korea Contents Association
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• v.10 no.3
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• pp.10-20
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• 2010

This paper presents chunking strategy of a contiguous nouns sequence using semantic class. We call contiguous nouns which can be treated like a noun the compound noun phrase. We use noun pairs extracted from a syntactic tagged corpus and their semantic class pairs for chunking of the compound noun phrase. For reliability, these noun pairs and semantic classes are built from a syntactic tagged corpus and detailed dictionary in the Sejong corpus. The compound noun phrase of arbitrary length can also be chunked by these information. The 38,940 pairs of 'left noun - right noun', 65,629 pairs of 'left noun - semantic class of right noun', 46,094 pairs of 'semantic class of left noun - right noun', and 45,243 pairs of 'semantic class of left noun - semantic class of right noun' are used for compound noun phrase chunking. The test data are untrained 1,000 sentences with contiguous nouns of length more than 2randomly selected from Sejong morphological tagged corpus. Our experimental result is 86.89% precision, 80.48% recall, and 83.56% f-measure.

• Korean Journal of Materials Research
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• v.5 no.7
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• pp.765-774
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• 1995

The hot deformation behaviour of particulate reinforced aluminium 6061 Al composite were investigated by hot compression tests in the temperature range from 623K to 823K with strain rate of 10$^{-3}$ ~5.0 S$^{-1}$ . The effect of reinforced particulate volume fraction, mean diameter on the high temperature flow stress has also been studied. Experimental results showed that the increase in the volume fraction of reinforcement contributed to the rising of yield stress, but the stress above the yield point appeared to be steady state at all volume fractions. The apparent activation energy for deformation was 290KJ/mo1 for unreinforced 6061 Al, 327KJ/mo1 for 6061 Al-20vo1.% SiC composite and 531KJ/mo1 for 6061 Al-20vo1.%A1$_2$O$_3$composite. It appeared that $Al_2$O$_3$reinforced composites was more difficult to hot deform.

• Journal of Korea Society of Industrial Information Systems
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• v.11 no.5
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• pp.170-180
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• 2006

The increase in international logistics market and various customer demands emphasize the importance of Multimodal Transportation, and that market is continuously keeping growing. In order to ensure competitive superiority in a market of such infinite competition, service that can satisfy each individual customer by considering various customer characteristics, has become an issue. Thus, through the aspect of service, in order to improve customer satisfaction, growing factors of Multimodal Transportation Route was studied in this research. For this research, first of all main service factors that affect the growth of Multimodal Transportation were seized by literature survey and positive research. Then, by using these factors a methodology that enables individual customers to assess Multimodal Transportation Route was studied. Through this research, individual customers can acquire objective assessment data and Multimodal Transportation companies can seize what factors are considered as important by their customers.