• 대한전자공학회논문지TC
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• 제47권6호
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• pp.42-48
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• 2010

군용 통합 전술 정보 통신 체계(JTIDS: Joint Tactical Information Distribution System)에서 사용하는 기저대역 변조 방식 중 하나인 순환 부호 편이 변조 (CCSK: Cyclic Code Shift Keying) 방식은 5개의 비트를 32개의 32칩 수열로 변환하는 일종의 직접 수열 기반 대역 확산 변조 방식이다. 순환 부호 편이 변조 방식은 총 32개의 비직교 수열을 사용한다. 본 논문에서는 CCSK를 기반으로 하는 비동기 검파 성능을 분석하였다. 또한, 보다 나은 성능을 가지는 32칩 수열을 제안하고, 종래의 32칩 수열과 성능을 비교하였다.

• 한국터널지하공간학회 논문집
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• 제25권4호
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• pp.305-330
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• 2023

쉴드TBM 터널은 NATM 터널과 달리 라이닝이 세그먼트로 분절되어 있다. 따라서 라이닝에 동일 하중이 발생되어도 NATM 터널 라이닝과 쉴드TBM 터널 라이닝의 응력 분포가 다르게 발생된다. 쉴드TBM 터널에서 라이닝에 발생되는 응력을 분석하는 대표적 방법은 연결부를 고려하지 않는 강성일체법과 링간 이음 및 세그먼트 연결을 고려하는 2링 빔스프링 모델이 있다. 본 연구는 라이닝 분절 Segmentaion을 고려한 Break-joint Mode 해석 방법이지만 세그먼트 라이닝 연결부의 구조적 역할을 고려하지 않고 마찰력 성분인 수직강성과 전단강성 만 도입된 쉘 인터페이스 요소를 이용한 모델링을 적용하여 진동하중 발생 시 라이닝의 응력 및 변위에 대한 응답결과를 분석했다. 토압 등 정적 하중에 대해 천 정부에서 가장 큰 응력이 발생되는 강성일체법과 달리 본 연구의 해석방법에 의해 발생된 세그먼트 라이닝 응력 분포는 세그먼트 연결부가 집중된 천정부 Key 세그먼트에서 가장 작은 응력이 발생하였고 연결부를 경계로 응력의 분포가 뚜렷이 구분되었다. 그리고 정적 해석 결과는 강성일체법에 발생된 라이닝 응력이 본 연구 방법에 의해 발생된 세그먼트 라이닝의 응력에 비해 최대 7배의 큰 응력이 발생되었다. 이러한 결과는 세그먼트 연결부를 고려한 기존의 2링 빔-스프링 모델의 응력분포 양상과 일치하는 결과다. 그러나 열차 진동하중에 대한 응력값은 Break-joint Mode로 해석한 본 연구방법의 응력이 강성일체법에 비해 더 큰 응력을 발생되었다. 이는 짧은 부재들의 조합으로 이루어진 세그먼트 Ring이 원주방향으로 일체로 되어 부재의 길이가 상대적으로 더 긴 강성일체법 결과에 비해 더 작은 응력이 발생되는 정역학적 개념과 상이한 결과다. 진동하중에 대해 Break-joint Mode에서 세그먼트 라이닝에 응력이 더 크게 발생된 원인은 부재의 고유주기, 감쇠비 등 동역학적 요인의 차이보다는 열차 진동하중에 대해 라이닝에 발생되는 변위의 차이에 기인하는 것으로 판단되지만 이에 대한 증명은 추후의 과제로 남겨두었다. 본 연구 방법의 Break-joint Mode를 이용하면 정지상태의 열차 하중에 의해 발생되는 라이닝의 응력과 변위값을 비교하여 쉴드TBM 터널의 충격계수(DIF)를 비교적 간단하게 추정할 수 있다. 본 연구는 쉴드TBM 터널의 Segmentaion을 고려한 3차원 모델링으로 추후 지진파 등 다양한 하중조건의 검토를 통해 기존 해석방법 결과와 비교하여 모델링의 추가적 신뢰성을 확보할 필요가 있다.

• ETRI Journal
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• 제34권5호
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• pp.783-786
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• 2012

This letter proposes a more advanced joint maximum a posteriori (MAP) adaptation using a prior model based on a probabilistic scheme utilizing the bilinear transformation (BIT) concept. The proposed method not only has scalable parameters but is also based on a single prior distribution without the heuristic parameters of the previous joint BIT-MAP method. Experiment results, irrespective of the amount of adaptation data, show that the proposed method leads to a consistent improvement over the previous method.

• Journal of Electrical Engineering and information Science
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• 제1권1호
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• pp.151-155
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• 1996

This paper derives the two-dimensional probability distribution and density functions of morphological dilation and erosion of a one-dimensional memoryless source and reports numerical results for a uniform source, thus providing methodology for joint distributions for other morphological operations. The joint density functions expressed in closed forms contain the Dirac delta functions due to the joint discontinuity within the dilation and erosion. They also exhibit symmetry between these two morphological density functions of dilated and/or eroded sources, in the computation of other higher moments thereof, and in multidimensional quantization.

• 유통과학연구
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• 제14권6호
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• pp.107-118
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• 2016

Purpose - Over 90% of Domestic logistics industry is small enterprise and they are experiencing growth stagnation due to price-based competition structure rather than constructing logistics service of high added value. In order to get over this situation and pursue the development of logistics industry, strengthening its competitiveness, through inter-enterprise cooperative network build-up, would be a key alternative. Therefore, in this study, an index for measuring inter-enterprise cooperation level of Joint logistics business will be developed as a typical collaborative business model in logistics industry. Moreover, a strengthening competitiveness method suggests a developmental step and a key management index to mature in logistics industry. Research Design, Data, Methodology - This study is an index development research for measuring inter-enterprise cooperation level of logistics industry. Such a level was measured by performing a survey by targeting enterprises that participated in Joint logistics business. The targeting enterprises are typical cooperative models in logistics industry. Measurement items were developed which were based on the presented items in existing research. Question items were composed of selection type questions as answering Yes/No. They measures implementation status of corporate activity and detailed activity items measuring qualitative level. Total samples were based on 116 enterprise samples including 90 logistics enterprises and 26 shippers. In addition, by evaluating the importance for Joint logistics business recognition with personnel working level, the weight of measuring variable was extracted. This study has built an assessment tools (LPCI) on Joint logistics business cooperation level in a situation where there are no previous studies on joint logistics business, this study is meaningful for other studies. Results - As a result of analyzing LPCI presented in this study, the score of logistics enterprise was represented as 59.9 points based on full score of 100 points and that of shippers as 47.2 points and cooperation level among enterprises participated in Joint logistics business was revealed to be very low. In particular, as a result of measuring the importance between logistics enterprise and shippers, the difference by each measurement standard was represented among those enterprises. This difference is considered to be a key factor that cooperative operational conformity between logistics enterprises and shippers is represented to be low. Conclusions - As most joint logistics business, being promoted at present, is sharing facility and information with joint logistics business, it is hard to find such a joint logistics business in reality based on cooperative business model in main cooperation agents. Therefore, competitiveness of logistics industry could be strengthened by promoting joint logistics business based on their mutual cooperation among enterprises. In other words, it is to secure sustainable competitiveness of joint logistics business together with creation of new market by inter-enterprise cooperation based on integration of basic logistics business.

• 한국생산제조학회지
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• 제21권2호
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• pp.290-296
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• 2012

Cold-rolled carbon steel sheets are commonly used in railroad car or commercial vehicles such as the automobile. These are mainly fabricated by spot welding which is a kind of electric resistance welding. But fatigue strength of spot welding joint is lower than that of base metal due to high stress concentration at nugget edge of the spot welded part. And fatigue strength of them is especially influenced by not only geometrical and mechanical factors but also welding conditions of the spot welded joint. So for fatigue design of gas welded joints such as TS-type joints, it is necessary to obtain design information on stress distribution at the weldment as well as fatigue strength of spot welded joints. And also, the influence of the geometrical parameters of spot welded joints on stress distribution and fatigue strength must be evaluated. And analysis approach for fatigue test using design of experiment are evaluated optimum factor in TS-type welded joint and geometrical parameters of materials. Using these results, that factors applied to fundamental information for automation of fatigue design.

• 대한물리의학회지
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• 제5권1호
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• pp.53-61
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• 2010

Purpose : The purpose of this study is to compare the distribution of foot pressure, knee and ankle joint angle between treadmill walking and ground walking in normal person. Methods : 18 Person of subject has participated this study, let subject to walk in ground and treadmill in order to gain data of foot distribution and knee, ankle joint angle using by parotec system. and Dartfish system. Walking velocity was constrained by 2Km/h and more 10sec. Date analysis was used by paired-t test using SPSS/PC statistical programs for window. Results : Result show that total contact times has shown symmetry between both legs, and more increase of left foot pressure in treadmill walking. Foot pressure of treadmill walking was significantly decreased in right hind foot and fore foot and hallux area. The ankle joint angle of treadmill walking was significantly decreased in initial contact phase. Conclusion : Results of this study show that foot pressure of treadmill walking was more decreased than ground walking in right hind foot and fore foot, hallux area. And the ankle joint angle of treadmill walking was significantly decreased in initial contact phase.

• Journal of Welding and Joining
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• 제17권6호
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• pp.53-61
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• 1999

The use of thick plate in increasing in recent years due to the rapid expansion of chemical plants, nuclear plants, ships and other industrial plants. Welding is the most popular joining techniques employed in manufacturing industrial machineries and structures. Normally, Groove shapes are prepared according to appropriate rules and regulations such as KS, JIS, AWS, LR, DNV and etc. for various thicknesses of plate. However those groove angles tend to be too large. As a result of large groove angle, residual stress, deformation of material and strength reduction is obtained. Therefore, the reliability and safety of structures and machinery tend to be decreasing. Therefore, in this paper, theoretical as well as experimental study are carried out to find optimum groove shapes for T-welded joint of mild steel. The test specimen are made in same condition with simulation model. Welding residual stresses measurement by sectional cutting method. ⅰ) The mechanical difference for change the thickness of plate and groove angle are not appeared. ⅱ) In a mechanical point of view minimum preparation angle(40°) is more suitable than maximum groove angle(60℃). ⅲ) The measurement value and distribution of welding residual stresses are not effected largely by groove angle. It is mechanical restraint that mainly affect welding residual stresses distribution. In mechanical point of view minimum groove angle is more suitable than maximum groove angle. Therefore, it is appropriate to minimize the size of groove shape in strength and safety.

• 한국구조물진단유지관리공학회 논문집
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• 제10권5호
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• pp.187-193
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• 2006

도로교 프리캐스트 바닥판의 현장 조인트로써 특수한 구조의 클램프를 이용하여 새로운 형식의 조인트를 개발하였다. 이 클램프 조인트에 의한 방법은 클램프를 이용하여 주철근을 루프 조인트에 연결하는 방법이다. 현재까지 일반적으로 사용되고 있는 루프 조인트와 비교하여 시공성 경제성이 우수하고 클램프의 인터록킹에 의하여 휨모멘트 전단내력에 효과를 나타내었다. 본 논문은 휨 강성 및 전단내력의 실험을 통하여 조인트의 파괴 메커니즘과 다양한 정적 거동의 결과를 규명하고자 일련의 실험을 수행하였다. 이러한 실험 연구의 결과로부터 루프조인트와 동등한 성능을 갖고 있다는 결론을 얻었다.

• 대한토목학회논문집
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• 제31권6C호
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• pp.203-212
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• 2011

본 논문은 암반지층에 설치되는 굴착벽체의 안전하고 경제적인 설계 및 시공을 위해 절리가 형성된 암반지층에서 발생하는 토압의 크기 및 분포특성을 조사한 것이다. 이러한 목표를 위해, 먼저 기존 선행연구의 한계성 및 문제점을 파악하고 이를 극복하기 위해 암반지층의 다양한 절리특성 등을 고려할 수 있는 개별요소법(DEM)에 근거한 불연속체 수치해석적 매개변수 연구를 수행하였다. 매개변수로는 암반종류 및 절리상태(절리면의 전단강도 및 절리경사각)가 고려되었으며, 지반과 굴착벽체의 상호작용을 반영하면서 각 요소의 영향이 고려된 토압크기 및 분포특성이 파악되었다. 뿐만 아니라, 암반지층에서 발생된 토압과 토사지반에서의 경험토압인 Peck토압과의 상호 비교가 이루어졌다. 비교결과 절리가 형성된 암반지층에서 발생된 토압의 크기 및 분포는 암반의 종류 및 절리상태에 따라서 크게 영향을 받은 것으로 나타났고 토사지반에 있어서 Peck의 경험토압과 비교하여 서로 다른 특징을 나타내었다. 이와 같이 조사된 결과는 향후 절리가 형성된 암반지층에서의 굴착벽체 설계를 위한 토압산정에 필요한 정보 및 기초자료로서 활용될 것이다.