The technology competitions of automobile manufacturers are getting hot. The characteristics of the environment friendly automobile are not only lowering the emission of harmful exhaust gas through the change of the power source, but also paying great attention to improvement of the power efficiency. As the market for pure electric vehicles continues to grow, we have analyzed the global technology competitiveness by DCT (Dual Clutch Transmission) patents. Clustering can be classified into five types ; 1) a cluster associated with a dual clutch transmission system, 2) a cluster of a torque transmission device and a reverse speed ratio, 3) a cluster of co-planar sets and dual clutch assemblies related to transmitting devices, 4) Device clusters, and 5) a cluster of synchronizers and clusters to prevent simultaneous operation of dual clutch transmissions. In recent years, demand for pure electric vehicles has been rapidly increasing, and patent applications related to DCT have been steadily increasing for energy efficiency of motor power sources.

In this study, total mercury (THg) variations of Black-tailed Gull (Larus crassirostris) eggs laid on Baengnyeongdo, West Sea of Korea were compared between within- and among clutch in order to ensure statistical representativeness of an egg sampling method. In the ANOVA analysis, the THg variation (59%) among clutches was much higher than within-clutch (27%). This means that the mercury variation of sampled eggs was significantly influenced by the mercury variation among female individuals occupying different nests. In spite of relatively smaller variation of THg in the within-clutch, the THg concentration depending on an egg-laying sequence within a clutch significantly appeared higher in the first-laid eggs rather than the second-laid eggs. Therefore, it is necessary to take one egg from one nest in order to sample more nests in terms of better sampling representativeness. Also, one egg selection from one nest should be consistently applied in order to ensure comparability of mercury concentrations among monitoring sites and monitoring years.

A precise control of the launcher in MLRS(Multiple Launcher Rocket System) is important for a mission completion. During the field operation of the MLRS, a friction noise was heard in the elevation clutch that controls the launcher. It was confirmed that unsteady friction between friction plates and clutch plates has caused the noise in the clutch. Conducting the analysis of drive mechnism in the clutch, there was a possibility of the unsteady friction because of moderated spring constant. Therefore, after performing experiments on the elevation clutch varied with spring constant, it was determined the proper spring constant. Finally, an improvement on the spring constant in the elevation clutch is expected in the future by utilizing the result of this study.

This paper is a case study of reliability assessment with field warranty data of Clutch Master Cylinder (CMC) in hydraulic clutch system. We estimate lifetime distribution using field warranty data which contain much useful information for understanding reliability of the system in the real-world environments. However, the estimated parameters are far from existing reference values, which seems to be caused right censored field warranty data. To modify the parameters, we use the information of the durability test which is performed to verify that the lifetime of the item meets the required level. After that, we can observe that the modified parameters are closer to the existing reference values. This case study shows a possible idea to supplement lack of right censored field warranty data and its applicability.

This paper is a case study of reliability assessment with field warranty data of Clutch Master Cylinder(CMC) in hydraulic clutch system. We estimate lifetime distribution using field warranty data which contain much useful information for understanding reliability of the system in the real-world environments. However, the estimated parameters are far from existing reference values, which seems to be caused right censored field warranty data. To modify the parameters, we use the information of the durability test which is performed to verify that the lifetime of the item meets the required level. After that, we can observe that the modified parameters are closer to the existing reference values. This case study shows a possible idea to supplement lack of right censored field warranty data and its applicability

2004년 2월부터 2005년 6월까지 제주특별자치도 애월읍 신엄리에서 흑로의 번식과정을 조사하였다. 한배 산란수는 3.24±0.75개(N=17, 범위 2~4개)였으며, 알은 새벽이나 밤에 1~3일 간격으로 산란하였다. 알(N=39)의 크기는 장경 46.73±l.91mm, 단경 34.06±0.83mm, 무게 27.67±3.12g, 두께 0.26±0.03mm였다. 흑로의 둥지 보수나 짓기는 매년 2월부터 시작해서 늦게는 4월말까지, 산란기는3월초부터 늦게는 5월 초순까지였고, 부화기는4월 초순에서 5월 중순까지, 이소기는 5월 중순부터 7월말까지였다. 보충 산란은 1차 번식과정 중 포란과 육추에 실패한 5~6월에 바로 시도하는 것으로 추정된다. 포란 기간은 28.17±4.12일(N=6)이었으며, 알은 비동시성으로 부화되었다. 육추 기간은 40.00±6.84일(N=5)이었으며, 새끼의 부리, 날개, 부척, 체중의 성장속도는 부화가 빠른 개체일수록 빠른 경향을 보였다. 우리나라에서 번식하는 백로과 조류의 산란시기를 비교해보면, 흑로는 왜가리보다는 느렸으나, 해오라기, 쇠백로, 중대백로는 보다는 빨랐다.

본 논문에서는 유한요소법을 활용하여 소형전자기클러치(micro-electromagnetic clutch)에서 발생하는 마찰토크와 응답시간을 해석하였다. 소형전자기클러치의 설계변경과 최적화를 위하여 전자석클러치에서 자기장에 의하여 발생하는 전달토크와 응답시간을 정확하게 예측 할 것이 요구된다. 해석을 위하여 전자기장 이론을 기반으로 소형전자기클러치의 축대칭 모델을 구성하고 실제 재료 물성치를 대입하여 토크와 응답시간을 해석하고 유한요소 해석결과의 정확성을 검증하기 위하여 실험결과와 비교하였다. 토크와 응답시간의 해석결과는 실험데이터와 거의 일치하다는 것을 통하여 해석적 방법으로 토크와 응답시간을 예측할 수 있음을 확인 할 수 있다.

A variable release torque-based compliance spring-clutch (VCSC) is presented. VCSC is a safe joint to reduce the impact of collisions between humans and robots. It is composed of four functional plates, balls, springs to make some functions in compliant movement, release mechanism, gravity compensation during its work. Also, it can estimate torque applied to a joint by using distance sensor and parameters of cam profile. The measured variable torque of prototype is 4.3~7.6 Nm and release torque is 4.3 Nm. In our future studies, a calibration for torque estimation will be conducted.