• 한국철도학회:학술대회논문집
• /
• 한국철도학회 2010년도 춘계학술대회 논문집
• /
• pp.583-589
• /
• 2010

This paper describes the design process and the test of split wheel-mounted brake discs for high speed train with maximum speed 180km/h. A disc set composed 2 disc rings and individual rings are partitioned into 3 pieces with the same circumferential angle. Because partitioned disc rigs are exposed to severe centrifugal force as the vehicle speed increase, finite element analyses used in the design process to ensure mechanical safety. A prototype was verified its mechanical safety through the spin test up to 250km/h. 2 prototypes for 1 wheelset are mounted to Korean Tilting Train(TTX) and have been running over 15,000km

• 한국IT서비스학회지
• /
• 제11권4호
• /
• pp.251-262
• /
• 2012

Unit testing is one of the test levels, which tests an individual unit or a group of related units. Recently, in Agile Development or Safety-critical System Development, the unit testing plays an important role for the qualities. According to the definition of unit testing, it is supposed to be done by the developers of units. That is because test models for the unit testing refers to the structure of units, and others but its original developers hardly can understand the structures. However, in practice, unit testing is often asked to be done without the original developers. For example, it is when faults are revealed in customer sites and the development team does not exit any more. In this case, instead of original developers, other developers or test engineers take a product and test it. The unit testing done by a non-developer, who is not the original developer, would cause some difficulties or cause more cost. In this paper, we tests an open source, JTopas, as a non-developer, with building test models, implementing test codes, and executing test cases. To fit this experiment to practical testing situations, we designed it based on the practices of unit testing, which were surveyed through SPIN(Software Process Improvement Network). This paper analyzes which part of unit testing done by non-developers needs more effort compared to the unit testing done by original developers. And it concludes that Agile Development contributes on reducing the extra effort caused by non-developers, since it implements test codes first before developing source code. That means all the units have already included their own tests code when they are released.

• 한국추진공학회지
• /
• 제15권3호
• /
• pp.40-46
• /
• 2011

75톤급 터보펌프용 속도복식 터빈을 개발하였다. 축과 로터의 연결에는 커빅커플링을 적용하였다. 커빅커플링은 시편을 통한 고온비틀림 시험과 시제품의 스핀시험을 통해 적용 적합성을 검증하였다. 고압 공기를 이용한 성능시험 결과, 개량형 속도복식 터빈의 비출력은 기본형 단단 터빈에 비해 설계점에서 20.5%가량 향상된 것으로 나타났다. 개량형터빈의 $1^{st}$로터는 설계점 전체출력의 74.1%를 담당하는 것으로 확인되었다.

• Composites Research
• /
• 제18권1호
• /
• pp.45-54
• /
• 2005

필라멘트 와인딩 공정으로 제작된 고속 회전용 복합재 플라이휠 로터는 층간분리 현상에 의해 에너지 저장용량이 저하된다. 그리고 기존의 링 타입 허브는 복합재 로터 내측면에 인장력을 가하게 되고. 이는 로터내의 반경방향 인장응력을 가중시켜 로터의 한계 회전수를 저하시킨다. 복합재 로터의 응력해석을 위해서 2차원 평형방정식과 경계조건이 사용되었고, 이를 근거로 강도비를 최소화시키는 최적의 내압이 존재함을 수치적으로 제시하였다. 이러한 최적의 내압을 발생시키기 위해서 원주방향으로 분할된 스플릿 타입 허브를 제안하고, 링 타입과 스플릿 타입 허브의 두께변화에 따른 내압분포의 영향을 제시하였다. 스플릿 타입 허브의 유효성을 검증하기 위해 허브를 포함한 복합재 로터를 제작한 다음, 최대 회전수 40,000rpm까지 파손 없이 스핀 테스트를 수행하였다. 동시에 로터 표면에 4개의 원주방향 및 반경방향 스트레인게이지를 부착하여 변형률을 무선으로 측정하였다. 측정된 변형률은 해석결과와 매우 잘 일치하였다. 특히 반경방향의 응력을 크게 낮출 수 있었고, 반경방향으로 모두 압축 변형률이 발생함을 확인하였다. 결국 스플릿 타입 허브는 플라이휠 로터의 단점인 반경방향의 낮은 강도를 보안하는 효과를 나타내어, 저장에너지 밀도를 증가시킴으로써 대형 고출력 플라이횔 에너지 저장 시스템의 개발 가능성을 제시하였다.

• 한국컴퓨터정보학회논문지
• /
• 제20권3호
• /
• pp.89-96
• /
• 2015

IT 기술이 생체역학 분야와 폭넓게 접목되고 있으며 AHRS 센서가 스포츠 모션분석 분야에 소형화 및 가격 경쟁력 측면에서 조명을 받고 있다. 본 논문에서는 피겨스케이트화에 소형의 AHRS 센서를 부착하고, 스핀(spin), 점프, 전/후진, 인/아웃 에지, 토(toe) 등의 기본 동작을 AHRS를 통해 측정한다. AHRS 센서의 측정 오차를 줄이기 위해 Madgwick의 상보필터를 적용하였으며, 짐벌락 현상(Gimbal Lock)을 줄이기 위해 쿼터니언(Quaternion)을 이용하였다. 취득한 9축 궤적 정보에 대해 PCA, ICA, LDA, SVM의 패턴인식 알고리즘을 적용하여 인식정확도 및 실행시간을 구하고, 여러 패턴인식 알고리즘 중에서 어떤 알고리즘이 인식정확도 및 실행시간 측면에서 적용이 가능한지 제시한다. 실험결과, PCA, ICA는 인식정확도가 낮아 사용하기에 부적합하며 LDA, SVM은 인식정확도가 우수하여 피겨스케이팅 기본 동작 인식에 사용이 적합함을 보인다.

• 한국운동역학회지
• /
• 제25권1호
• /
• pp.11-19
• /
• 2015

Objective : The purpose of this study was to analyze the correlation between physical factors (X-factor, X-factor stretch) and club factors (club speed, ball speed, club path, smash factor, vertical launch angle, spin rate, flight time, total length) during impact and it affect on the total distance of the ball during a golf driver swing. Background : There were not enough studies that analyzed the correlation between physical factors(X-factor, X-factor stretch) and club factors(club speed, ball speed, club path, smash factor, launch angle, spin rate, flight time, total length) during a purpose swing to increase total distance. Method : For this study, 9 right handed professional male golfers (KPGA) were chosen. The test subject group used their own drivers and each took a total of 10 swings. These swings consisted of 5 purpose swings to increase total distance and 5 normal swings. Results : The purpose swing to increase total distance showed larger physical factors(X-factor, X-factor stretch) compared to a normal swing however the results were not statistically significant. Total distance increased during a purpose swing as a result of ball and club speed. Conclusion : The results showed that club factors, ball speed and club speed contributed the most in affecting the total distance of the ball during a purpose swing.

• 천문학회보
• /
• 제41권1호
• /
• pp.54.2-54.2
• /
• 2016

Korea Microlensing Telescope Network (KMTNet) is the first optical survey system of its kind in a way that three KMTNet observatories are longitudinally well-separated, and thus have the benefit of 24-hour continuous monitoring of the southern sky. The wide-field and round-the-clock operation capabilities of this network facility are ideal for survey and the physical characterization of small Solar System bodies. We obtain their orbits, absolute magnitudes (H), three dimensional shape models, spin periods and spin states, activity levels based on the time-series broadband photometry. Their approximate surface mineralogy is also identified using colors and band slopes. The automated observation scheduler, the data pipeline, the dedicated computing facility, related research activity and the team members are collectively called 'DEEP-South' (DEep Ecliptic Patrol of Southern sky). DEEP-South observation is being made during the off-season for exoplanet search, yet part of the telescope time is shared in the period between when the Galactic bulge rises early in the morning and sets early in the evening. We present here the observation mode, strategy, software, test runs, early results, and the future plan of DEEP-South.

• Imaging Science in Dentistry
• /
• 제45권3호
• /
• pp.159-168
• /
• 2015

Purpose: This study was performed to compare the metal artifacts from common metal orthodontic brackets in magnetic resonance imaging. Material and Methods: A dry mandible with 12 intact premolars was prepared, and was scanned ten times with various types of brackets: American, 3M, Dentaurum, and Masel orthodontic brackets were used, together with either stainless steel (SS) or nickel titanium (NiTi) wires. Subsequently, three different sequences of coronal and axial images were obtained: spin-echo $T_1$-weighted images, fast spin-echo $T_2$-weighted images, and fluid-attenuated inversion recovery images. In each sequence, the two sequential axial and coronal images with the largest signal-void area were selected. The largest diameters of the signal voids in the direction of the X-, Y-, and Z-axes were then measured twice. Finally, the mean linear values associated with different orthodontic brackets were analyzed using one-way analysis of variation, and the results were compared using the independent t-test to assess whether the use of SS or NiTi wires had a significant effect on the images. Results: Statistically significant differences were only observed along the Z-axis among the four different brands of orthodontic brackets with SS wires. A statistically significant difference was observed along all axes among the brackets with NiTi wires. A statistically significant difference was found only along the Z-axis between nickel-free and nickel-containing brackets. Conclusion: With respect to all axes, the 3M bracket was associated with smaller signal-void areas. Overall, the 3M and Dentaurum brackets with NiTi wires induced smaller artifacts along all axes than those with SS wires.

• 한국전기전자재료학회:학술대회논문집
• /
• 한국전기전자재료학회 2006년도 하계학술대회 논문집 Vol.7
• /
• pp.169-170
• /
• 2006

In this study, ultra thin films of ferroelectric vinylidene fluoride-trifluoroethylene (VF2-TrFE) copolymer were fabricated on degenerated Si (n+, $0.002\;{\Omega}{\cdot}cm$) using by spin coating method. A 1~5 wt% diluted solution of purified vinylidene fluoride-trifluoroethylene (VF2:TrFE=70:30) in a dimethylformamide (DMF) solvent were prepared and deposited on silicon wafers at a spin rate of 2000~5000rpm for 30 seconds. After annealing in a vacuum ambient at $200^{\circ}C$ for 60 min, upper gold electrodes were deposited by vacuum evaporation for electrical measurement. X-ray diffraction results showed that the VF2-TrFE films on Si substrates had $\beta$-phase of copolymer structures. The capacitance on $n^+$-Si(100) wafer showed hysteresis behavior like a butterfly shape and this result indicates clearly that the dielectric films have ferroelectric properties. The typical measured remnant polarization (2Pr) and coercive filed (EC) values measured using a computer controlled a RT-66A standardized ferroelectric test system (Radiant Technologies) were about $0.54\;C/cm^2$ and 172 kV/cm, respectively, in an applied electric field of ${\pm}0.75\;MV/cm$.

• 공업화학
• /
• 제22권2호
• /
• pp.230-234
• /
• 2011

반도체산업은 고집적화된 회로를 요구하면서 미세 패턴을 형성하기 위해 계속해서 발전해가고 있다. 이에 반도체 산업에서 미세 패턴을 형성하기 위하여 하드마스크를 도입하여 사용되고 있다. 일반적으로 하드마스크는 화학증기증착법(CVD) 공정을 이용하여 다층구조로 제작된다. 이에 본 연구에서는 스핀공정이 가능하고 단층의 하드마스크용 조성물을 제조하기 위하여 유-무기 하이브리드 중합체를 이용하여 그 특성에 대하여 연구하였다. Silanol로 처리된 siloxane 화합물과 acetonide 그룹을 가지는 propionic acid를 에스터화 반응을 통하여 얻은 유-무기 하이브리드 중합체에 가교제 및 첨가제들의 첨가로 광학적, 열적, 그리고 표면 특성이 조절된 하드마스크 막을 제조하였다. 또한 하드마스크 막과 감광층의 식각비를 비교하여 유-무기 소재의 하이브리드 중합체에 대해 미세패턴을 형성시킬 수 있는 하드마스크 막으로써의 유용성을 확인하였다.