• 한국정밀공학회지
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• 제23권1호
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• pp.166-173
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• 2006

This paper investigated strength of a bogie frame for Korean tilting train that is being developed in KRRI. In this study, static load tests based on Japanese Industrial Standard (JIS) were performed. In order to simulate vertical and lateral components generated by tilting link mechanism, four hydraulic actuators were used. The eight load cases such as vertical, lateral, traction, braking and driving gear loads were applied for evaluation of the strength of bogie frame. The stresses measured at the stress concentration points were assessed using Goodman diagram. From the experimental results, structural safety of the bogie frame could be ensured.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2002년도 ICCAS
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• pp.105.6-105
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• 2002

Contents 1We developed a new type of lower part of the human-sized BWR (biped walking robot) driven by a new actuator based on the ball screw which has high strength and high gear ratio. Each leg of the robot is composed of three pitch Joints and one roll joint. In all, a 8 degree-of-freedom robot was developed. A new type of actuator for the robot is proposed, which is composed of four bar link mechanism driven by the ball screw. The BWR was designed to walk autonomously by adapting small DC motors for the robot actuators and has an embeded controller system including host computer, batteries and motor drivers. In the performance test, we had basic stable walking data so far, but we f...

• The Journal of Advanced Prosthodontics
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• 제5권4호
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• pp.464-470
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• 2013

PURPOSE. The aim of this Fourier transform infrared (FTIR) spectroscopic study was to measure the degree of conversion (DC) of dual-cured resin cements light-irradiated through zirconia ceramic disks with different thicknesses using various light-curing methods. MATERIALS AND METHODS. Zirconia ceramic disks (KT12) with three different thicknesses (1.0, 2.0, and 4.0 mm) were prepared. The light transmittance of the disks was measured using ultraviolet visible near-infrared spectroscopy. Four different light-curing protocols were used by combining two curing light modes (Elipar TriLight (standard mode) and bluephase G2 (high power mode)) with light-exposure times of 40 and 120 seconds. The DCs of the two dual-cured resin cements (Duo-Link and Panavia F2.0) light-irradiated through the disks was analyzed at three time intervals (3, 7, and 10 minutes) by FTIR spectroscopy. The data was analyzed using repeated measures ANOVA (${\alpha}$=.05).Two-way ANOVA and Tukey post hoc test were used to analyze the 10 minute DC results. RESULTS. The 1.0 mm thick disk exhibited low light transmittance (<25%), and the transmittance decreased considerably with increasing disk thickness. All groups exhibited significantly higher 10 minute DC values than the 3 or 7 minute values (P<.05), but some exceptions were observed in Duo-Link. Two-way ANOVA revealed that the influence of the zirconia disk thickness on the 10 minute DC was dependent on the light-curing methods (P<.001). This finding was still valid even at 4.0 mm thickness, where substantial light attenuation took place. CONCLUSION. The curing of the dual-cured resin cements was affected significantly by the light-curing technique, even though the additional chemical polymerization mechanism worked effectively.

• 한국시스템다이내믹스연구
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• 제10권3호
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• pp.105-124
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• 2009

The situation of the global food markets has been being rapidly restructured and entering on a new phase by new dynamic and driving forces. The factors such as economic growth and income increase, high energy price, globalization, urbanization, and global climate change are transforming patterns of food consumption, production, and markets. The prices and markets of world food and energy are getting increasingly linked each other. Food and fuel are the global dilemma issues associated with the risk of diverting farmland or of consuming cereals for biofuel production in detriment of the cereals supply to the global food markets. An estimated 100 million tons of grain per year are being redirected from food to fuel. Therefore, the objectives of this study are as follows: Firstly, the study examines situations of the world food and energy resources, analyzes the trends of prices of the crude oil and biofuel, and formulates the food-energy links mechanism. Secondly, the study builds a simulation model, based on system dynamics approach, for not only analyzing the global cereals market and energy market but also forecasting the global production, consumption, and stock of those markets by 2030 in the future. The model of this study consists of four sectors, i.e., world population dynamics sector, global food market dynamics sector, global energy market dynamics sector, scenario sector of world economic growth and oil price.

• 한국자동차공학회논문집
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• 제10권1호
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• pp.209-215
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• 2002

A study of the guideway vehicle was made for a comparison of ride stabilities between its two primary steering types; one is the front wheel steering and the other the front-rear wheel. A numerical model as a closed loop system was built for an investigation of various factors to have an influence on the vehicular critical speed which is closely associated with ridabilities. It was shown that dynamics stabilities of the front steering type was much better over a large value of steering gain and the longer distance between front axle and guide link for both types provided better stabilities as well. A large steering gain ratio of the front to the rear significantly plays an important role in an improvement of stability in the front-rear steering. To observe a qualitative trend on stability behaviors, the root locus was obtained by considering a time lag which may be frequently caused by the complicated steering mechanism. In performing so, the appropriate selection of steering gain had a greater effect on the front-rear steering vehicle far more ride comfort. In addition, the dynamics model proposed here can be utilized for a more accurate evaluation on the vehicle design in lateral or yawing absorber and moreover expanded for the analysis of independent four-wheel steering vehicle.

• 한국농업기계학회:학술대회논문집
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• 한국농업기계학회 1993년도 Proceedings of International Conference for Agricultural Machinery and Process Engineering
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• pp.734-743
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• 1993

The performances of three same type of vibrating potato diggers were estimated by observing the potato separation and material flow on the bottom plate. Four-bar mechanism were adopted for three diggers and pairs of eccentric cams on both sides of driving shaft were used as driving link of the diggers. Each machine was tested with different amplitudes , frequencies, and travels speeds. Blade performance were observed in three categories : Impossible forward travel , acceptable operation, and unsatisfactory potato digging , but good material flow. Three parameters were used to set marginal values that enable the machines operate for potato digging, and the parameters were compared to select best one. Three parameters are λ, $\rho$, and K.λ is the ratio of vibrating speed to travel speed, $\rho$ is the ratio of blade acceleration to travel speed, and K is the ratio of blade acceleration to gravitational acceleration. K value of 2 or more is suggested to be used as design and evalu tion criterion of the vibrating digger.

• 한국기계가공학회지
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• 제20권9호
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• pp.42-47
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• 2021

A one-touch descending lifeline that can easily be installed and rapidly evacuated in the event of a fire accident in high-rise buildings was proposed to overcome difficulties of conventional descending lifeline such as complex installation methods and procedures. However, this lifeline exhibits limitations such as restrictions in installation location and large apparatus size. Therefore, this paper proposes a sliding-type descending lifeline, which has a similar operation to that of current one-touch descending lifeline and solves the aforementioned limitations. A double square link mechanism including a sliding four-bar linkage is proposed and the descending lifeline support is redesigned to unfold in two different planes, allowing 3D movement. Additionally, the shape of the support frame is designed to obtain two attachment surfaces that can be attached to a wall, irrespective of the angle between the window and the inner wall. FEA analysis using ABAQUS is performed to ensure that the robustness of the presented support complies with the Fire Control Act Enforcement Decree. Finally, the feasibility of the proposed sliding one-touch descending lifeline is verified through fabrication.

• BMB Reports
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• 제55권4호
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• pp.161-165
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• 2022

The mechanistic target of rapamycin (mTOR) regulates numerous extracellular and intracellular signals involved in the maintenance of cellular homeostasis and cell growth. mTOR also functions as an endogenous inhibitor of autophagy. Under nutrient-rich conditions, mTOR complex 1 (mTORC1) phosphorylates the ULK1 complex, preventing its activation and subsequent autophagosome formation, while inhibition of mTORC1 using either rapamycin or nutrient deprivation induces autophagy. Autophagy and proteasomal proteolysis provide amino acids necessary for protein translation. Although the connection between mTORC1 and autophagy is well characterized, the association of mTORC1 inhibition with proteasome biogenesis and activity has not been fully elucidated yet. Proteasomes are long-lived cellular organelles. Their spatiotemporal rather than homeostatic regulation could be another adaptive cellular mechanism to respond to starvation. Here, we reviewed several published reports and the latest research from our group to examine the connection between mTORC1 and proteasome. We have also investigated and described the effect of mTORC1 inhibition on proteasome activity using purified proteasomes. Since mTORC1 inhibitors are currently evaluated as treatments for several human diseases, a better understanding of the link between mTORC1 activity and proteasome function is of utmost importance.

• 한국경영과학회:학술대회논문집
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• 한국경영과학회 1998년도 추계학술대회 논문집
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• pp.114-117
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• 1998

Failure to link business or operations strategy with the activities of operations is a critical problem in strategy implementation process. This problem comes from malfunction of a coordination and control mechanism to support the strategic direction by effective communication throughout the firm. A performance measurement and evaluation system (PMES) is thought as a core mechanism to monitor, direct. and induce desirable activities. We have developed a new strategic PMES (SPMES) that can effectively support the manufacturing strategy by utilizing customized performance measures. They are selected from a pool of four distinct but closely related sets of performance measures; financial, market, internal competency, and performance driver. In this paper, we briefly review the structure of the SPMES and explain the change process of PMES into SPMES in manufacturing business units. First we analyze the business environment and manufacturing strategy to identify short- and long-term issues facing the management. Next step is scrutinizing the objectives and activities of every function and process in the business unit. Using the information obtained, we can diagnose the gaps between currently effective PMES and desirable SPMES supporting the strategies. Once the problems in existing system are identified, we reconfigure the existing and new measures to establish a SPMES through a series of analyses, discussions and workshops. In organizing the selected measures in the new system, we use AHP method to reflect the relative importance of the measures in a specific business. Finally, modification or development of information system to support the SPMES wraps up the development process, and implementation begins. We explain the entire process using two cases to clarify the real meanings and the difficulties of PMES change process.

• 항공우주시스템공학회지
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• 제11권5호
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• pp.36-41
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• 2017

위성 궤도 내 우주 잔해가 늘어남에 따라 현재 운용 중인 위성들과 폐위성과의 충돌 위험이 지속적으로 증가하는 추세이다. 위 문제를 해결하기 위해 본 연구에서는 1 자유도의 간단한 메커니즘을 사용한 포획장치를 설계하였다. 포획장치는 net가 연결된 4개의 링크군으로 구성되었다. 또한 신뢰도를 높이기 위해 4개의 링크군을 하나의 구동부에 연결하여 자유도가 1이 되도록 설계하였다. 포획장치가 청소위성(janitor위성)의 임무수행에 영향을 끼치지 않도록 위성의 옆면에 수납하였다. 최종적으로 우주 환경에서의 전개 가능성을 파악하기 위해 미세중력 환경을 모사한 수중환경에서 포획장치 전개 실험을 수행하였다. 포획장치 전개실험 중 janitor위성과의 간섭 없이 전개완료 됨을 확인함으로써 대상 위성 포획에 대한 가능성을 검증하였다.