• 한국자동차공학회논문집
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• 제12권1호
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• pp.106-113
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• 2004

Most of mechanical structures are composed of many substructures connected to one another by various types of mechanical joints. In automotive engineering, it is important to study these connected structures under various dynamic forces for the evaluations of fatigue life and stress concentration exactly. In this study, the dynamic response of vehicle structure to external forces is classified an inverse problem involving strains from the experiment and the analysis. The practical dynamic forces are determined by the combination of the analytical and experimental method with analyzed strain by quasi-static finite element analysis under unit force and with measured strain by a strain gage under driving load, respectively. In a stressed body, inter-molecular chemical bonds are failed beyond the certain magnitude. The failure of molecular structure in material is considered as a time process of which rate is determined by mechanical stress. That is, the failure of inter-molecular chemical bonds is the fatigue lift of material. This kinetic concept is expressed as lethargy coefficient. And S-N curve is obtained with the lethargy coefficient from quasi-static tensile test. Equivalent practical dynamic force is obtained from the identification of practical dynamic force for one loading point. Using the practical dynamic force and S-N curve, fatigue life of a window pillar is analyzed with FEM under the identified force by the procedure of above mentioned.

• 전기전자학회논문지
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• 제25권2호
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• pp.315-321
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• 2021

본 논문에서는 초소형 반도체 부품 IC 소켓 검사에 필요한 다중 채널 시험장치를 개발한다. 이 시험장치는 저 저항(수 mΩ급)으로 저전류(수 uA급)~5A 범위의 미세전류상태에서 생산 시스템 요구 규격에 맞는 IC를 다양한 형태로 시험분석을 실행한다. 0.25 mm이하의 리드피치(Lead Pitch)를 가진 IC 소켓 채널수의 증가로 다양한 시험을 동시에 실행해야하는 시험장비는 회로의 고집적화를 위하여 여러 개의 SMU(Source Measure Unit) 보드를 동시에 탑재하도록 구성된다. Daisy chain test method를 통하여 채널지점(Channel Point)당 약 2분 소요되는 시험시간(Test Time)을 40 초(sec) 이내로 단축이 가능하고, 그래픽 기반 인터페이스, 분석 도구(I-V Curve Mode 등) 및 데이터 로깅(Data Logging)을 통한 테스트 플로우 분석을 구현함으로써 시험시간과 소요비용을 절감한다.

• 한국가정과교육학회지
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• 제15권1호
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• pp.81-94
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• 2003

This study tested students’ ICT application capability and Problems solving ability by ICT instructional environment when ICT teaching method is applied to $\boxDr$Understanding of Myself and Family$\boxUl$ unit of home economics. Following research Problems were formulated for this study : 1. Are there any differences of the effects on improvements of students’ ICT application capability by ICT instructional environment\ulcorner 2. Are there any differences of effects on improvements of students’ problems solving ability by ICT instructional environment\ulcorner 3. Are there any differences of effects on improvements of students’ Performance assessment results by ICT instructional environment\ulcorner The researcher developed a homepage for the ICT teaching-learning. and prepared Problems-based teaching-learning lesson plan. The students were divided into two groups (experimental group 1 and experimental group 2) by ICT instructional environment. The Pre-test and post-test were conducted before and after the experimental class. The ICT class experimental period was for 16 weeks. from March 10. 2002 to July 10. 2002. The experimental group 1 was given 16-weeks classwork under the classroom environment of 1 PC for each classroom(The classroom with advanced educational equipments) . while the experimental group 2 was given 16-weeks classwork under the classroom environment of 1 PC for each student(multimedia classroom) . The results of the study are as follows: 1 All of the ICT teaching methods under both instructional environments were found to be effective on the improvements of the ICT application capability. 2. There were statistically significant differences of problems solving ability between two groups in application and the measure of validation. 3. The experimental group 1(1 PC for each classroom) did not show any improvements of Performance assessment results. while the experimental group 2(1 PC for each student) showed some improvements.

• 한국생산제조학회지
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• 제21권1호
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• pp.175-181
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• 2012

This paper presents a novel dynamic vibration absorber (DVA) to suppress the unbalance response of flexible rotor-bearing systems. The DVA unit consists of two DVAs, an adapter to place the DVAs and an adapter frame to locate the adapter. The essential feature of the proposed DVA unit is to place itself on any desirable location of the shaft without disassembling the rotor-bearing system under consideration. A simulation with a 3D element based commercial rotor dynamic software is made to test the possibility of the proposed DVA on the suppression of unbalance response in rotor-bearing systems. Experiments are performed to validate the proposed DVA unit. The simulation and experiments show that the proposed DVA unit is very effective to suppress the unbalance response in rotor-bearing system at designated rotational speeds of interest.

• 농촌계획
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• 제19권4호
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• pp.1-15
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• 2013

The purpose of this study is to quantitatively analyze the corresponding residents' benefit to get in the future from the district unit plan of the settlement zone by Cheongju local government. The target districts were selected as Gumdeong-gol district, Juseong district, and Shinmok-gol district, and Hyeonam district which had recently set their district unit plans. Specific targets to be analyzed were some infrastructure including roads, parking lots, parks and others. Using the analysis methods of the Logit model and non-parametric test approach, this study estimated to the average amounts to be willingly paid(WTP) by the residents in targeting settlement zones and tested the reliability of the average amounts of WTP. The results of analysis were as follows. First, it was found that the WTPs for infrastructure under 1st influence area in target districts were estimated as 5,233won for road, 2,826won for parking lot, and 3,705won for park respectively. For the WTPs for infrastructure under 1nd area were estimated as 4,910 won for road, 2,242won for parking lot, and 3,620won for park respectively. Second, as the result of calculating the non-parametric WTP which built the 95% confidence interval, it was found that the all WTPs except the WTP for parking lot were fell into the 95% confidence interval. Third, as the result of calculating yearly total sum of benefits that the residents would get from the 1st influence area and the 2nd influence area, it was found that Gumdeong-gol district were expected to get 62,376,472won-amounted benefits, and Juseong district, and Shinmok-gol district, and Hyeonam district would get 35,0778,016won, 26,886,560won, and 22,252,032won respectively.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2003년도 컴퓨터소사이어티 추계학술대회논문집
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• pp.27-30
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• 2003

The recent technology developments introduce new difficulties into the test process by the increased complexity of the chip. Most widely used method for testing high complexity and embedded systems is built-in self-test(BIST). In this paper, we describe 5-stage pipeline system as circuit under testing(CUT) and proposed a BIST scheme for the hazard detection unit of the pipeline system. The proposed BIST scheme can generate sequential instruction sets by pseudo-random pattern generator that can detect all hazard issues and compare the expected hazard signals with those of the pipelined system. Although BIST schemes require additional area in the system, it proves to provide a low-cost test solution and significantly reduce the test time.

• Journal of the Korean Data and Information Science Society
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• 제17권3호
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• pp.945-952
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• 2006

Several accelerated life test plans use tests at only two levels of stress and thus, have practical limitations. They highly depend upon the assumption of a linear relationship between stress and time-to-failure and use only two extreme stresses that can cause irrelevant failure modes. Thus 3-level stress plans are preferable. When the lifetime distribution of test unit is exponential with mean lifetime $\theta_i$ at stress $x_i$, i=0, 1, 2, 3, we derive the optimum quadratic plan under the assumption that a quadratic relationship exists between stress and log(mean lifetime), and propose the compound linear plans, as an alternative to the optimum quadratic plan. The proposed compound linear plan is better than two other compromise plans for constant stress testing and nearly as good as the optimum quadratic plan, and has the advantage of simplicity.

• 한국항해학회지
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• 제16권1호
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• pp.1-12
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• 1992

In this study, the self test-system for the marine Gyrocompass was developed and the obtained results are summarized as follows : 1) Utilizing the newly developed self-test system, the time length for observing the transient state of Gyrocompass reading which has been over 4 hours can be reduced to less than 20 minutes. In addition, the dynamic characteristics of the Gyrocompass can be measured within 2 hours after starting the system. 2) Prior test and diagnosis was done by checking all parameters recurrently with period of 2.5minutes. 3) Testing and diagnosis results was shown in graphic mode and could be transmitted to INMARSAT unit using personal computer. 4) The results of the newly designed trouble algorithm for the system was found to be applicable under arbitrary given conditions.

• 대한조선학회논문집
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• 제58권3호
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• pp.158-166
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• 2021

In this paper, a numerical analysis technique using a body force model is investigated to estimate the available net thrust of multi-pod-driven ice-breaking vessels under bollard pull and overload conditions. To employ the body force model in present flow simulations, drag and thrust components acting on the pod unit are calculated by using Propeller Open Water (POW) test data. The available net thrusts according to the direction of operation are evaluated in both bollard pull and overload conditions under deep water. The simulation results are compared with the model test data. The available net thrusts, calculated by the present analysis for ahead operating modes at 3~6 knots which are typical speeds of the target vessel in arctic field, are agreed well with the model test results. It is also found that the present result for astern operating mode appears approximately 6 % larger than the model test result. In addition, the available net thrusts are calculated under the both operating conditions accompanied by shallow water effects, and the main cause of the difference is studied. Based on the result of the present study, it is confirmed that the body force model can be applied to the performance evaluation of multi-pod propulsion system and the main engine selection in early design stage of the vessel.

• 대한건축학회논문집:구조계
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• 제34권4호
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• pp.25-33
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• 2018

In regard to modular systems, new methods, as well as middle and high-story unit design ideas, are currently being studied. These studies need to focus on the enhanced stiffness and seismic performance of these connections, and see that the development of fully restrained moment connections can improve the seismic performance. For this reason, this study evaluates the performance of the connections of the ceiling bracket-typed modular system through repeated loading tests and analyses. In order to compare them with these modular units, new unit specimens with the bracket connection being different from that of the traditional modular unit specimens were designed, and the results of repeated loading tests were analyzed. In the traditional units, the structural performances of both welding connection and bolt connection were evaluated. In regard to the testing results, the initial stiffness of the hysteresis curve was compared with the theoretical initial stiffness, and the features of all specimens were also analyzed with regard to the maximum moment. In addition, the test results were examined with regard to the connection flexural strength of the steel special moment frame specified under the construction criteria KBC2016. The connections, which were proposed in the test results, were found to be fully restrained moment connections for designing strong column-weak beams and meeting the requirements of seismic performance of special moment frames.