• 한국철도학회:학술대회논문집
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• 한국철도학회 2005년도 추계학술대회 논문집
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• pp.146-151
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• 2005

Main parameters of wheel-rail combination are investigated by profile analysis. A rolling radius difference is one of the main characteristics that describe a contact between wheelset and railway track, which in turn defines the dynamic behavior of a wheelset. This paper describes functional relation between lateral wheelset displacement and rolling radius difference or conicity on new/worn wheel of existing narrow gauge vehicle. Information about curving behavior and running stability are given by this both relations. The optimal wheel profile for railway vehicle with narrow gauge is adopted through this analysis. And, the applicable limit value of conicity which is used in order to do dynamic simulation of vehicle is presented.

• 한국항해항만학회지
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• 제31권9호
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• pp.763-769
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• 2007

A narrow loop noise bandwidth method is desirable to reduce the error of raw measurements due to the thermal noise. However, it degrades the performance of GPS initial synchronization such as mean acquisition time. And it restricts the loop noise bandwidth to a fixed value determined by the lower bound of the allowable range of carrier-to-noise power ratio, so that it is difficult to optimally track GPS signal. In order to make up for the weak points of the fixed-type narrow loop noise bandwidth method and simultaneously minimize the error of code and carrier measurements, this paper proposes a stepwise-type adaptive bandwidth algorithm for DGPS reference receivers. In this paper, it is shown that the proposed adaptive bandwidth algorithm can provide more accurate measurements than those of the fixed-type narrow loop noise bandwidth method, in view of analyzing the simulation results between two signal tracking algorithms. This paper also carries out sensitivity analysis of the proposed adaptive bandwidth algorithm due to the estimation uncertainty of carrier-to-noise power ratio. Finally the analysis results are verified by the experiment using GPS simulator.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2001년도 하계종합학술대회 논문집(2)
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• pp.265-268
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• 2001

In this paper we investigate the implementation cost of value prediction methods for high performance micro-processors, and propose a new value prediction microarchitecture with low cost. After simulation, we found that the proposed microarchitecture can decrease the implementation cost by 36% to 50% and with slight performance degradation (less than 5%) .

• 구강회복응용과학지
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• 제34권1호
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• pp.32-38
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• 2018

목적: 3.6 mm 이하 좁은 직경 임플란트의 일정 기간 생존율을 초기고정 값과 방사선학적 계측을 통해 분석해보고자 하였다. 연구 재료 및 방법: 24명의 환자에 식립된 직경 3.6 mm 이하, 길이 7 mm 이상의 38개의 임플란트를 조사하였다. 식립된 임플란트의 platform 직경, body 직경, 길이, 식립 부위 등을 확인하였고 식립 시 골유도재생술의 동반 시행 여부, 완성된 보철의 형태를 확인하였다. 초기고정 값은 임플란트 식립 직후 측정한 implant stability quotient (ISQ) 값을 확인하였고, 방사선 사진을 통해 식립된 임플란트의 근 원심 marginal bone level (MBL)을 측정하였다. 결과: 전체 임플란트의 생존율은 92.11% 이었고 ISQ값은 평균 66.26으로 나타났다. 생존한 임플란트의 MBL 변화는 평균 $0.14{\pm}0.31mm$를 나타내었다. Platform 직경이 body 직경보다 큰 임플란트 중 실패한 임플란트는 없었다. 결론: 좁은 직경의 임플란트는 좁은 직경의 치조제에 안정적인 치료 결과를 나타낸다 사료된다.

• 대한기계학회논문집A
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• 제34권1호
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• pp.67-72
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• 2010

원전 배관의 LBB 해석을 위한 파괴인성(J-R곡선)은 일반적으로 ASTM E1820에 따라 시험을 수행하여 획득한다. 그러나 ASTM E1820에 제시되어 있는 파괴인성에 관한 식은 균질재의 물성 평가를 위한 것 이며, 협개선 용접부에 적용할 경우 실제와는 다른 파괴인성을 나타낼 수 있다. 따라서 본 연구에서는 ASTM에 제시되어 있는 균질재의 파괴인성식에 의한 결과와 협개선 용접재의 특성을 고려하여 제안된 소성 $\eta$계수 식에 의한 파괴인성의 차이를 비교 검토하기 위하여 협개선 용접이 적용된 배관에서 CT 시험편을 채취한 후 파괴인성 시험을 수행하였다.

• 한국군사과학기술학회지
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• 제15권6호
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• pp.721-728
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• 2012

The tracked SUGVs(Small Unmanned Ground Vehicles) are frequently operated in the narrow slope such as stairs and trails. But due to the nature of the tracked vehicle which is steered using friction between the track and the ground and the limited field of view of driving cameras mounted on the lower position, it is not easy for SUGVs to trace narrow slopes. To properly trace inclined narrows, it is very important for SUGVs to keep it's heading direction to the slope. As a matter of factor, no roll value control of a SUGV can makes it's heading being located in the direction of the slope in general terrains. But, the problem is that we cannot directly control roll motion for SUGV. Instead we can control yaw motion. In this paper, a new slope driving method that enables the vehicle trace the narrow slopes with IMU sensor usually mounted in the SUGV is suggested which including an estimation technique of the desired yaw angle corresponding to zero roll angle. In addition, a fuzzy steering controller robust to changes in driving speed and the stair geometry is designed to simulate narrow slope driving with the suggested method. It is shown that the suggested method is quite effective through the simulation.

• 유통과학연구
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• 제14권2호
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• pp.93-101
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• 2016

Purpose - This study aims to advance our knowledge about factors influencing technical startup performance through analysing technical startup process empirically. This study was conducted to focus on industry structure(industry growth rate, competitive intensity, and enter barriers), technology characteristics(technical excellence and wide range of technical application), and the performance in the technology-based start-ups. Specifically, analyzing moderating effect of technology-marketing strategy, this studied how moderating variables affect technical startup performance under industry structure. Research design, data, and methodology - The subject of this study was technology-based start-ups company that received technology transfer from public organization. The development of the paper model is based on the literature of the preceding research analysis in technology commercialization, performance of technology-based start-ups, and marketing strategy. This study has a construct that was defined in the previous studies, such that technology marketing strategy was defined into the two ways of being broad or narrow in strategic application. From November 3. 2015 to December 22, 220 questionnaires were distributed with targeting to start-up companies in technology-based. 188 responses were collected for empirical analysis except the missing and wrong value responses. This data were used for structural equation modeling and regression analysis. Results - The results of this study are as follows. First, as industry structure variables influencing on performance(technical, financial) of technology-based start-ups, industry growth rate, competitive intensity and enter barriers of variables were verified; high growth rate has more positive effect on performance than low growth rate, competitive low intensity has more positive effect on performance than competitive high intensity, low enter barriers have more positive effect on performance than high enter barriers. Second, as technology characteristics variables influences on the performance(technical, financial) of technology-based start-ups, technical excellence and wide range of technical application of variables were verified ; technical high-excellence has more positive effect on performance than technology low-excellence, wide range of technical application has more positive effect on performance than narrow range of technical application. We also find that technology marketing strategy(broad/narrow) in moderating factors on performance (technical, financial) is as follows. Analyzing the moderating effect depending on technology marketing strategy(broad/narrow), application of technology, and the types of technology strategy(broad/narrow) were revealed that broad marketing strategy had a more significant effect on performance of technology-based start-ups. With AMOS, the relevancy of the study model revealed higher for broad technology-marketing strategy than narrow technology marketing strategy, and the explanatory power revealed to be 6.4% higher in broad marketing strategy than narrow marketing strategy. Conclusions - This study confirmed that industry structure and technology characteristics are important factors influencing the performance of technology-based start-ups. Technology-marketing strategy affects the performance of technology-based start-ups between industry structure and technology characteristics. According to additional analysis, moderating variables and technology-marketing strategy are important factors influencing the performance of technology-based start-ups under industry structure and technology characteristics. Broad type of technology-marketing strategy has more attractive industry structure and excellent technology characteristics than narrow types of technology-marketing.

• 해양환경안전학회지
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• 제28권4호
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• pp.525-532
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• 2022

목포항은 우리나라에서 가장 많은 연안여객선과 연안여객선의 항로를 운영 중이며, 지형적인 영향으로 목포항으로 입출항하는 연안여객선은 서남해안 곳곳의 좁은 수로를 통항하고 있다. 상대적으로 대형선박이 이용하는 항로에 비하여 연안여객선이 이용하는 좁은 수로에 대한 해상교통환경의 안전성을 체계적으로 검토한 사례는 찾아보기 어렵다. 이에 본 연구에서는 목포항 항계 부근에 위치한 좁은 수로에 대하여 대상이 되는 연안여객선의 통항 안전성을 항만 및 어항설계 기준에서의 항로 폭, 수심, 굴곡도 기준에 따라 분석하였다. 분석 결과, 맥도와 달리도 사이의 좁은 수로 폭이 대상 연안여객선이 통항 가능한 전장의 1.5배보다 좁을 뿐만 아니라, 수로의 굴곡 정도가 기준값인 30°를 초과하여 조선이 쉽지 않고, 좁은 수로 인근에 어구가 다수 존재하여 통항 시 지장을 초래하는 것으로 나타났다. 따라서, 본 연구의 결론으로, 동 좁은 수로에서 대상 연안여객선의 주간 단독 통항 및 야간·시계제한·저조 시의 경우 항내의 지정 항로로 우회하여 통항할 것을 개선방안으로 제시하였다.

• Bulletin of the Korean Chemical Society
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• 제33권11호
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• pp.3749-3754
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• 2012

Nanoporous carbons with a high specific surface area were prepared directly from thermoplastic acrylic resin as carbon precursor and MgO powder as template by carbonization over the temperature range, $500-1000^{\circ}C$. The effect of the carbonization temperature on the pore structure and $CO_2$ adsorption capacity of the obtained porous carbon was examined. The textural properties and morphology of the porous carbon materials were analyzed by $N_2/-196^{\circ}C$ and $CO_2/0^{\circ}C$ adsorption/desorption isotherms, SEM and TEM. The $CO_2$ adsorption capacity of the prepared porous carbon was measured at $25^{\circ}C$ and 1 bar and 30 bar. The specific surface area increased from 237 to $1251m^2/g$, and the total pore volumes increased from 0.242 to $0.763cm^3/g$ with increasing the carbonization temperature. The carbonization temperature acts mainly by generating large narrow micropores and mesopores with an average pore size dependent on the level of carbonization of the MgO-templated nanoporous carbons. The results showed that the MgO-templated nanoporous carbons at $900^{\circ}C$ exhibited the best $CO_2$ adsorption value of 194 mg/g at 1 bar.

• Restorative Dentistry and Endodontics
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• 제17권1호
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• pp.235-243
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• 1992

The purpose of this study was to evaluate the accuracy of an electronic apex locator, the Neosono - M, in determining the location of the cementodentinal junction. A total of 26 teeth with 46 canals were evaluated. The apex locator was used to locate the file and the teeth extracted. The specimen were prepared with highspeed burs and sandpaper discs to a thickness of $250{\sim}300{\mu}m$. Distances were measured from the cementodentinal junction with the use of polarizing microscope. Measurements made by the apex locator were also compared with those by the X - ray. The results were as follows. 1. The apex locator and X - ray were to measure a mean value of 0.17, 0.45mm coronal to the CDJ respectively. There was no significant difference between the accuracy of the apex locator and that of X - ray. 2. There was no significant difference between the accuracy of apex locator in vital and in nonvital teeth, and between in narrow and in wide canals. 3. The files in nonvital and narrow group were apical to the CDJ significantly than those of vital and narrow, vital and wide, and non vital and wide groups.