• 반도체디스플레이기술학회지
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• 제21권4호
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• pp.65-70
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• 2022

In manufacturing and semiconductor industries, transfer robots increase productivity through accurate and continuous work. Due to the nature of the semiconductor process, there are environments where humans cannot intervene to maintain internal temperature and humidity in a clean room. So, transport robots take responsibility over humans. In such an environment where the manpower of the process is cutting down, the lack of maintenance and management technology of the machine may adversely affect the production, and that's why it is necessary to develop a technology for the machine failure diagnosis system. Therefore, this paper tries to identify various causes of failure of transport robots that are widely used in semiconductor automation, and the Prognostics and Health Management (PHM) method is considered for determining and predicting the process of failures. The robot mainly fails in the driving unit due to long-term repetitive motion, and the core components of the driving unit are motors and gear reducer. A simulation drive unit was manufactured and tested around this component and then applied to 6-axis vertical multi-joint robots used in actual industrial sites. Vibration data was collected for each cause of failure of the robot, and then the collected data was processed through signal processing and frequency analysis. The processed data can determine the fault of the robot by utilizing machine learning algorithms such as SVM (Support Vector Machine) and KNN (K-Nearest Neighbor). As a result, the PHM environment was built based on machine learning algorithms using SVM and KNN, confirming that failure prediction was partially possible.

• 국제학술발표논문집
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• The 9th International Conference on Construction Engineering and Project Management
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• pp.443-449
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• 2022

With climate change and the global population growth, the frequency and scope of wildfires are constantly increasing, which threatened people's lives and property. For example, according to California Department of Forestry and Fire Protection, in 2020, a total of 9,917 incidents related to wildfires were reported in California, with an estimated burned area of 4,257,863 acres, resulting in 33 fatalities and 10,488 structures damaged or destroyed. At the same time, the ongoing development of technology provides new tools to simulate and analyze the spread of wildfires. How to use new technology to reduce the losses caused by wildfire is an important research topic. A potentially feasible strategy is to simulate and analyze the spread of wildfires through computing technology to explore the impact of different factors (such as weather, terrain, etc.) on the spread of wildfires, figure out how to take preemptive/responsive measures to minimize potential losses caused by wildfires, and as a result achieve better management support of wildfires. In preparation for pursuing these goals, the authors used a powerful computing framework, Spark, developed by the Commonwealth Scientific and Industrial Research Organization (CSIRO), to study the effects of different weather factors (wind speed, wind direction, air temperature, and relative humidity) on the spread of wildfires. The test results showed that wind is a key factor in determining the spread of wildfires. A stable weather condition (stable wind and air conditions) is beneficial to limit the spread of wildfires. Joint consideration of weather factors and environmental obstacles can help limit the threat of wildfires.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2016년도 제50회 동계 정기학술대회 초록집
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• pp.77-77
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• 2016

Thin films synthesized by plasma processes have been widely applied in a variety of industrial sectors. The structure control of thin film is one of prime factor in most of these applications. It is well known that the structure of this film is closely associated with plasma parameters and species of plasma which are electrons, ions, radical and neutrals in plasma processes. However the precise control of structure by plasma process is still limited due to inherent complexity, reproducibility and control problems in practical implementation of plasma processing. Therefore the study on the fundamental physical properties that govern the plasmas becomes more crucial for molecular scale control of film structure and corresponding properties for new generation nano scale film materials development and application. The thin films are formed through nucleation and growth stages during thin film depostion. Such stages involve adsorption, surface diffusion, chemical binding and other atomic processes at surfaces. This requires identification, determination and quantification of the surface activity of the species in the plasma. Specifically, the ions and neutrals have kinetic energies ranging from ~ thermal up to tens of eV, which are generated by electron impact of the polyatomic precursor, gas phase reaction, and interactions with the substrate and reactor walls. The present work highlights these aspects for the controlled and low-temperature plasma enhanced chemical vapour disposition (PECVD) of Si-based films like crystalline Si (c-Si), Si-quantum dot, and sputtered crystalline C by the design and control of radicals, plasmas and the deposition energy. Additionally, there is growing demand on the low-temperature deposition process with low hydrogen content by PECVD. The deposition temperature can be reduced significantly by utilizing alternative plasma concepts to lower the reaction activation energy. Evolution in this area continues and has recently produced solutions by increasing the plasma excitation frequency from radio frequency to ultra high frequency (UHF) and in the range of microwave. In this sense, the necessity of dedicated experimental studies, diagnostics and computer modelling of process plasmas to quantify the effect of the unique chemistry and structure of the growing film by radical and plasma control is realized. Different low-temperature PECVD processes using RF, UHF, and RF/UHF hybrid plasmas along with magnetron sputtering plasmas are investigated using numerous diagnostics and film analysis tools. The broad outlook of this work also outlines some of the 'Grand Scientific Challenges' to which significant contributions from plasma nanoscience-related research can be foreseen.

• 한국지반공학회논문집
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• 제30권12호
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• pp.15-25
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• 2014

본 연구에서는 지리산 북쪽의 과거 산사태 발생영역에서 조사된 절리특성과 GIS를 이용하여 추출한 지형특성을 근거하여 연구지역에서 예상되는 암반사면 파괴유형을 분석하였다. 또 해발고도, 사면방향, 사면경사, 음영도, 곡률, 하천 이격거리 등 6개의 지형특성 인자의 빈도비를 중첩하여 산사태 예측도를 작성하였으며, 산사태 예측도와 도로 및 주거지와 같은 지역의 인문적인 인자를 고려한 산사태 피해도를 조합하여 최종적으로 연구지역의 산사태 위험도를 작성하였다. 연구지역에서 발생한 산사태의 지형적 특성을 분석한 결과, 해발고도 330~710m에서 88%, 사면방향 동남-남-남서 방향($90{\sim}270^{\circ}$)에서 77.7%, 사면경사 $10{\sim}40^{\circ}$에서 93.39%, 음영도 등급3~7에서 82.78%, 곡률특성 -5~+5에서 86.28%, 하천 이격거리 400m 이내에서 82.92%가 발생하였다. 산사태가 발생한 영역의 75%는 산사태 위험도에서 위험 등급이 '높음' 이상인 지역이어서 위험 예측에 대한 신뢰성이 확인되었으며, 연구지역의 13.27%는 산사태 위험에 노출된 것으로 분석되었다.

• 기술혁신학회지
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• 제10권2호
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• pp.230-254
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• 2007

과학기술이 다양해지고 융합기술이 발달함에 따라 동료평가만으로 기술과 성과를 평가하는 것은 더욱 어려워졌다. 해당 전문가를 찾기도 쉽지 않을 뿐만 아니라 연구자들 사이에 이해관계가 한층 복잡해졌기 때문이다. 과학계량학(Scientometrics)은 과학자의 연구활동을 정치성이나 이해관계를 배척하고 객관적으로 계측하여, 성과에 비해 시그널이 약하게 발산되는 우수한 연구자나 연구 분야를 찾아내어 올바른 평가를 가능하게 한다. 본 논문에서는 OLED 기술에 대해 집계분석과 몇 가지 네트워크 분석 기법을 활용하여 과학계량학적 분석을 수행하고, 결과에 대해 한국에서는 어떤 평가가 가능한지에 대해 기술한다.

• 한국항해학회지
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• 제21권3호
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• pp.1-18
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• 1997

From the beginning of 1990s , also in the shipping industry, especially liner shipping industry competition has been more intensive and difference of the service quality among shipping companies has been learned . On the other hand, a shipping company has some limitations to do its international mission for itself just by broadening service area. For this reason, the necessity for the global strategi alliance among the shipping companies, which is orginally aimed at sharing of facilities and organixation, has been developed. Through strategic alliance, liner shipping companies do not need to input the additional capitals to increase the material assets such as vessel capacity and spread the risk by the enlargement of the market. Also, they can secure the competitive edge through efficient utilizaton of assets. The purpose of strategic alliance of Hanjin Shipping Ltd., can be summarized as follows ; broadening of service area, cost reduction through vessel sharing, realization of rationalized shipping service by terminal and equipment or facilities sharing. Liner strategic alliances are agreement among liner companies to pol their equipment , andterminals for joint operations and services in which each alliance partner continues to serve its market using jointly operated or used inland feeders,inland terminals, port terminals, and mainline fleets of ship as well as joint pools of containers and equipment. Strategic alliances are generally more formal agreements than consortia and impose longer term and far reaching obligation on their members. It also acts as one in developing and advancing the strategic aims of the alliance members. The most important objective for liner strategic alliances is cost reduction and improvement in capital asset utilization. Main aims of strategic alliance drawn in this paper, can be enumerated follows : 1. improvements in service frequency and quality : 2. improvements in vessel and equipment utilization and thereby reductions in fixed and variable cost ; 3. improvements in market shares and high value cargo booking ; 4. reductions in intermodal storage and port terminal throughput costs ; 5. improvements in negotiating powers with ports and feeder transport providers ; 6. reduction in financial and other fixed costs such as insurance; 7. coordination and integration of MIS and EDI systems and service for greater efficiency and market penetration ; and, 8. improvements in logistic chain management and economic of scale by equipment depot, terminal, and vessel sharing.

• 근관절건강학회지
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• 제9권1호
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• pp.18-27
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• 2002

Introduction : Exercise has been suggested as an important nursing strategy in which to help elderly maintain functional performance and to enhanced quality of life. Most of exercise study has been reported on fitness exercise such as walking, swimming, dance etc for health of elderly. There have been few reports about exercise on the promotion of small and fine movement of elderly. The purpose of this pilot study was to determine an effect of 6 weeks hand and finger exercise in home to improve hand muscle strength such as grip strength and finger pinch pressure. Materials and Methods Design: This pilot study was used one group pre and post-test design. Sample: Twelve elderly women above 60 years of age or older living in community were selected by convenient sampling. Procedure: Signed informed consent was obtained prior to participate in this study. The authors met elderly and taught hand and finger exercise, daily a week for 6 weeks, within 30 minutes per session. But exercise frequency and strength were not same. Instruments: Left and right grip strength were measured by Bulb Dynamometer(made in USA) and left and right pinch pressure were measured by Baseline Hydraulic Pinch Gauge(made in USA). Data analysis: Discriptive data analyses were performed on all variables. Wilcoxon matched-pairs Signed-Ranks test were used to find difference of grip strength and pinch pressure between pre and post exercise using SPSS 10.0 for Window. Results: Samples age ranged from 60 to 73, Mean age was 65.3. All were women. Ten elderly were diagnosed osteoarthritis and one had DM. After six weeks hand and finger exercise, Left and right grip strength were higher than those of before exercise(Z=-2.667, P<0.01 ; Z=-3.065, p<0.01). And left pinch pressure after hand and linger exercise were higher than that of before pinch pressure (Z=-2.315, p<0.05). But Right pinch pressure was not shown significant change(Z=-1.099, p>0.05). Conclusions: Although this study was limited by the sample size and design, the findings provide some important implications for community based exercise nursing intervention. Short term (six weeks) exercise of hand and linger is shown to be useful as nursing intervention to maintain routine daily activities such as eating, writing, grip something for elderly.

• 한국운동역학회지
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• 제13권3호
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• pp.47-65
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• 2003

The purpose of this study was to investigate the differences of the kinematical and the kinetical factors that calculated from preflight to postflight of salto forward straight 3/2 turn motion between skitters and less-skitters. four S-VHS video cameras operating at 60Hz were used to record the performances. five elite male gymnasts were participated in this study as subjects. three-dimensional coordinates of 20 body landmarks during each trial were collected using a Direct Linear Transformation method. The digitized body landmarks were smoothed using a Butterworth second order with low pass digital filter and a cutoff frequency of 10Hz. 1. A skitter, got a high score for performance, showed shorter time and faster horizontal velocity than a less-skitter at the board contact. also, a skitter extended quickly his knee and hip joint after contacting board for preflight phase. 2. A skitter revealed faster time and horizontal velocity the vault from taking off board than a less-skiller. A skitter took a long time and high distance to get the vertical peak compared with a less-skiller. 3. For the second phase, a skitter, who executes the most optimal motions among the subjects, displayed a long flight time, a high height, and a far flight distance as well as maintaining consistent horizontal speed even at the peak of post flight. On the other side, a less-scorer displayed a slow vertical velocity, distance and a short time at the point of take-off from vault as well as low height at the peak of post flight.

• 한국운동역학회지
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• 제22권3호
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• pp.285-293
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• 2012

The aim of this study is to identify the appropriate movement for maintaining postural balance during Front Kick and Turning Side Kick motions. To do so, ten Taekwondo athletes: five skilled players(S, body mass: $65.0{\pm}5.8kg$, height: $172.3{\pm}3.7cm$, age: $20.0{\pm}1.2yrs$, career: $9.0{\pm}1.9yrs$) and five less-skilled players(LS, body mass: $67.1{\pm}5.5kg$, height: $173.2{\pm}5.1cm$, age: $19.4{\pm}1.7yrs$, career: $9.6{\pm}1.7yrs$) participated in this study. A three-dimensional motion analysis was performed on the participants using eight infrared cameras and two force plate(sampling frequency of 200 Hz and 2000 Hz for S and LS players, respectively). The participants' motions were divided into: a front-kick phase(P1) and a turning-side-kick phase(P2). For P2(p<.05), the range and root mean square(RMS) of the ground reaction torque and the M-L mean velocity of COP were greater for LS than for S; similarly, for P2(p<.05), the M-L range, A-P range, and velocity of the COP were greater for LS than for S. Further, the M-L range and maximum velocity of the COP was greater for failure than for success(p<.05). The femoral biceps muscle for bending the knee joint was significantly stronger in S than in LS(p<.05). It is expected that these results will be useful in developing a training program for improving the balance and stability of Taekwondo poomsae athletes and improve their front-kick and turning-side-kick motions.

• Journal of Biosystems Engineering
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• 제35권1호
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• pp.21-30
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• 2010

This study was performed to develop an active tire pressure control system that can adjust tire pressure to the optimum level according to traveling and working condition of agricultural tractor. For the development of active tire pressure control system, pneumatic supplier, solenoid valve block including pneumatic supply line, infinite rotation type pneumatic supplier with rotary joint unit, tire pressure transceiver module and control algorithm were developed. Also, tire simulator was developed. Using this tire simulator, the feasibility of each part constructing actual system was tested by checking the performance. The average communication success ratio was 98.3% between tire pressure transmitter and receiver module according to the various tire rotational speed and data receipt position of receiver module. The communication performance of the developed transmitter and receiver module was very stable in any condition. The tire pressure control system was accomplished by using the proportional control algorithm in this study. Also tire pressure control performance of developed control system was analyzed by using the tire simulator. As a result of control performance analysis to the developed system, the developed control system took 307 seconds to inflate agricultural tractor's tire from 50 kPa to 180 kPa. In opposite case, it took 210 seconds. Also it was able to control the tire pressure accurately under ${\pm}0.9%$ (FS) in any condition.