• Korean Journal of Microbiology
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• v.38 no.4
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• pp.299-305
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• 2002

Clinically isolated Salmonella Enteritidis strain has a multi drug resistance plasmid, which confers ampicillin, chloramphe-nicol, sulfonamide, streptomycin and tetracycline, named pCAST2. We cloned a 7 kb Sacl fragment of pCAST2 which has sulfonamide, streptomycin and tetracycline resistance genes. The 7 kb SacI fragment showed the organization of sulII-strA-strB-tetR-tetA gene cluster which is different from the other clusters reported previously. In this study, we presented the method to detect this cluster by PCR analysis and showed that this cluster was found in Salmonella strains occurred sporadically at Kyungpook province in 2002.

• Proceedings of the Korea Concrete Institute Conference
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• 1997.04a
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• pp.285-291
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• 1997

This study is the experimental results on the applicability of the super flowing concrete, which is the pre-cast concrete, to various cases. The primary purpose of this study is to verify the demolding strength, the handling strength of the super flowing concrete at various curing conditions, and the site quality control of the DWS (Daewoo Multi-Room Modular Construction System). From the experimental works, required strength and curing cycles are satisfied. Furthermore site quality control details and quality of the pre-cast concrete using the super flowing concrete are obtained. From now on, this study may suggest how to apply the super flowing concrete for common circumstance.

• Nuclear Engineering and Technology
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• v.54 no.4
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• pp.1167-1174
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• 2022

Cast austenitic stainless steels (CASSs) are widely used as structural materials in the nuclear industry. The main drawback of CASSs is the reduction in fracture toughness due to long-term exposure to operating environment. Even though ultrasonic non-destructive testing has been conducted in major nuclear components and pipes, the detection of cracks is difficult due to the scattering and attenuation of ultrasonic waves by the coarse grains and the inhomogeneity of CASS materials. In this study, the ultrasonic signals measured in thermally aged CASS were discriminated for the first time with the simple ultrasonic technique (UT) and machine learning (ML) models. Several different ML models, specifically the K-nearest neighbors (KNN), Support Vector Machine (SVM), and Multi-Layer Perceptron (MLP) models, were used to classify the ultrasonic signals as thermal aging condition of CASS specimens. We identified that the ML models can predict the category of ultrasonic signals effectively according to the aging condition.

• Transactions of the Korean Society of Pressure Vessels and Piping
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• v.19 no.2
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• pp.171-178
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• 2023

For the phase boundary crack found in the gasket made of cast austenitic stainless steel in the nuclear power plant, the oxide layers were analyzed through SEM and TEM. The results showed that cracks initiated and propagated along the austenite/δ-ferrite phase boundary, the propagation path was changed to penetrate the inside of the phase. The oxide layer located at the periphery of the crack along the phase boundary was identified as a complex multi-layered spinel structure, and Cr-rich carbides were also detected in the oxide. The cracks that propagated inside the austenite matrix were attributed to the presence of high external stresses and impurities.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.38A no.7
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• pp.612-622
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• 2013

In this paper, we propose a coding packet group-based ARQ scheme (rNC) for file delivery in wireless networks. rNC assumes multiple network coding points between the source and the destination. Each network coding point gathers and codes a group of packets according to the queue polling system. A queue polling system makes a few or several packets available for coding in a queue while polling the other queues in the system. Thus, we assuem a queue polling system at each network coding point. We call this group of packets as coded packet group. Each coding point acknowledges the reception of every code packet group to its previous coding point for reliable delivery. Thus, the intermediate coding points including the source can release its buffer before the packet is delivered to the destination. To guarantee the ultimate file delivery to the destination, the destination sends acknowledgement to the sender. We evaluate our proposed scheme using ns-2 and compare the performance with CodeCast. The results show that rNC works better than CodeCast in terms of packet delivery ratio and control overhead in unreliable wireless networks.

• Journal of Internet Computing and Services
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• v.2 no.1
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• pp.77-85
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• 2001

CORBA is a middleware which enables distributed objects to cooperate regardless of specific platforms and techniques. But the ordinary CORBA communication model does not support multi-cast, and needs delay time, because it synchronously connects the distributed objects between client and server. To solve these problems, OMG suggests CORBA Event Service which can provide multi-cast among application objects. This paper presents a new technique for improving reliability, and supporting two-way communication by laying two interface objects on each consumers and suppliers that are registered in event channel. Also, to integrate objects efficiently, we, group distributed event channels and management it as view, A coordinator selected from channel group controls group and view.

• Proceedings of the Korea Information Processing Society Conference
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• 2006.05a
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• pp.1291-1294
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• 2006

우리는 P2P 네트워크 환경하에서 멀티캐스팅 스트리밍 전송방법으로서 포워딩 스트림 (forwarding stream)전송 방법을 사용한다. 일명 포워드캐스트(forwardcast)는 P2P 네트워크 환경과 멀티캐스팅 전송에 바탕을 두고, 클라이언트들의 자원을 효율적으로 이용함으로서 초기 클라이언트의 요청 기각률을 낮출 수 있었다. 본 연구에서는 이를 다수의 컨텐츠 서버 환경에 적용시킴으로서 하나의 서버에 집중되는 부하를 분산시킴과 동시에 초기 클라이언트의 기각률을 보다 낮추고자 한다. 실험결과 그 성능을 확인할 수 있었다.

• Proceedings of the Korea Information Processing Society Conference
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• 2000.10a
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• pp.35-38
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• 2000

본 논문에서는 기존의 워크플로우 모델을 바탕으로 역할을 기반으로 하는 새로운 개념의 모델을 제안하였으며, 이에 따른 워크플로우 업무 관리 시스템의 설계 및 구축 분야에서 역할 중심 업무 분산 체계(role oriented distribution)에 필요한 이론적 바탕을 마련하기 위한 역할 기반 모델(role based model)의 개념을 정의하고, 정의된 모델을 전형적 업무 관리 시스템인 워크플로우에 적용하였다. 본 논문에서 제시되어진 역할 기반 워크플로우 모델은 선택 할당(any-cast)방식 및 다중 할당(multi-cast)방식의 워크플로우 작업환경을 제공함으로써 현재 대부분 조직에서의 작업 환경인 객체지향 작업 환경 및 분산 작업 환경에서 워크플로우 관리 시스템을 구축할 수 있다.

• Journal of Industrial Technology
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• v.18
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• pp.203-208
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• 1998

Fatigue tests were performed to examine the 4 parameter method for specimens prepared by various heat treatment which resulted in different mechanical properties. Obtained main results are as follows. (1) Samples treated by austempering did not show the expected improvement of fatigue limit although hardness and strength increased. This is attributed to the fact that defect sensitivities of materials increase as increasing of hardness and tensile strength, it is also shown that the graphites acting as stress concentration place become larger by austempering heat treatment than by normal annealing. (2) It is very reasonable to predict the fatigue limit of ductile irons with 4 parameter method based on ${\sigma}_{TS}$, $H_v$, ${\Delta}K_{th}$ and ${\sqrt{area}}_{max}$. (3) The half-austempering treatment appeared to be more useful than the full-austempering method to improve the fatigue limit in the spheroidal graphite cast iron with multi defective material.

• Journal of Korea Foundry Society
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• v.17 no.5
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• pp.488-493
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• 1997

주방상태 및 열처리를 행한 다합금계백주철(Fe-5%Cr-5%V-5%Mo-5%W-X%C(X=0.5, 1.0, 1.5, 2.0, 2.5, 3.0)에 있어서 탄소함량이 탄화물의 형태 및 잔류오스테나이트의 함량에 미치는 영향에 관하여 연구하였다. 주방상태의 경우, 2.0% 이하의 탄소함량에서는 편상MC 및 층상 $M_2C$탄화물만 관찰되었으나 2.5%C 이상의 경우, 편상 및 괴상MC, 층상$M_2C$ 그리고 셀형 $M_7C_3$탄화물이 관찰되었다. 또한, 기지조직내 오스테나이트의 함량도 탄소첨가와 더불어 점차 증가하여 2.5%C에서 84.8%의 최대함량을 나타낸 후, 3.0%C에서는 다시 감소하였다. 또한 열처리한 시편의 경우, 1차탄화물의 형상은 주방상태의 그것과 비슷하였으나 열처리중 기지조직내 용해되었던 C, Cr, V, Mo, W등이 아주 미세한 2차탄화물의 형태로 석출되어 기지조직내 오스테나이트의 함량은 주방상태의 그것에 비해 감소하였다.