• 설비공학논문집
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• 제19권2호
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• pp.191-201
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• 2007

It was noted by the several researchers that the voltage outputs in response to a single yawed hot-wire sensor in a flow perpendicular to the axis deviate from the theoretical voltage output by King's law and Jorgensen's relation. This study noticed that the calibration coefficients of original Grande's method are not constant and fairly sensitive to the radial angle (${\alpha}_{R}$). For more accuracy, this study interpolated the parameters of the Grande relation as a function of radial angle and compared velocity components with ones by Jorgensen and original Grande relation in the calibration jet flow. Finally, as a test case, 3-dimensional turbulent flows of the inlet plane of 180 degree bend are measured and compared the velocity components by above three methods and showed the characteristics of the flows.

• 한국콘텐츠학회논문지
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• 제13권9호
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• pp.10-19
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• 2013

본 논문에서는 그래프 패턴 인식을 신속히 처리하기 위한 새로운 자성 센서의 개발과 인식 시스템을 제안하고자 하였다. 그래픽을 입력받아 세션화와 균형화를 수행하는데 있어서 특징점의 사전 처리를 선결 수행함으로써 인식 속도를 증강하고 선처리된 특징점을 이용하여 끝점, 굴곡점, 분기점의 특징점을 별도로 추출하지 않는 방법으로 조사하여 모음이나 자음의 부분패턴의 그래프 사전을 비교하는 간단한 구조해석과 인식을 도모하였다. 본 논문의 성능 비교를 위하여 사용자의 필기체를 사전에 등록 인식하고 입력 필기체를 비교 인식하여 Unicode로 변환시켜 비교한 결과 70%의 초기 인식률에서 누적 인공학습 지능 처리 결과 95%의 이상의 인식률을 보여주고 있다.

• 한국자동차공학회논문집
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• 제14권5호
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• pp.93-99
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• 2006

Flexible couplers are widely used for exhaust transmitted vibration reduction in vehicles. This paper describes an investigation into the acoustical characteristics of exhaust flexible coupler by the simulation and testing. Computational acoustic simulation is carrying out to investigate resonance frequency and transmission loss of decoupler using the boundary element method and transfer matrix approach. To confirm the acoustical simulation results of exhaust decoupler, we compare with measured experimental results by the test of transmission loss measurement system. In the comparison with simulation results and tests results, there is correctly fit the resonance frequency and the trend of transmission loss. Also, we show that the acoustical structure of decoupler is analogous to the expended tube or side branch resonator. The characteristics of exhaust decoupler have a marked increase in the acoustic attenuation at the specified frequency bend. Therefore the decoupler is applied to develop the exhaust system not only for the vibration isolator but also for the noise attenuator.

• 한국주조공학회지
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• 제7권2호
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• pp.114-121
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• 1987

In order to determine the plane strain fracture toughness of Al-Si-Cu-Mg alloy castings, solution heat treatments have been conducted at $530^{\circ}C$ for 8hr and aged for 10hr at $145^{\circ}C$, $160^{\circ}C$ and $175^{\circ}C$. Effects of aging treatment and of Si contents on the fracture toughness have been investigated by a three point loaded bend test, using the artificial notch. The results obtained are as follows; 1) The fracture toughness is appreciably affected by the aging treatment temperature and Si contents. The specimen aged for 10hr at $145^{\circ}C$ has the highest fracture toughness. 2) Increasing Si contents from 5% to 9% results in decrease of fracture toughness. 3) Increasing the aging temperature and Si contents, C.O.D. value was decreased. The specimen aged for 10hr at $145^{\circ}C$ has the highest C.O.D. value. 4) Dimple patterns were observed in the specimens of containing under 7% Si, while mixed cleavage-dimple patterns in those of over 8% Si.

• 한국재료학회지
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• 제16권12호
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• pp.743-746
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• 2006

ZTA tubes were prepared by centrifugal casting and sintered at $1600^{\circ}C$ for 2 hrs. The ZTA tubes were machined into specimens of $3{\times}4{\times}40$ mm. Molten Soda lime glass (SLG) was penetrated into the surface of ZTA at an optimized condition of $1500^{\circ}C$ for the holding time of 5 h and furnace cooled. The extra glass on the surface was removed using a resin bonded diamond wheel. The glass penetrated samples were tested for their flexural strength using four point bend test. Vickers Indentation cracks were made on the glass penetrated surface at different loads of 9.8 N, 49 N, 98 N and 196 N. The residual compression on the surface enhanced the flexural strength and crack arrest behaviour remarkably. This was attributed to the thermoelastic mismatch between the glass and ZTA matrix during cooling.

• 한국의류학회지
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• 제34권6호
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• pp.955-968
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• 2010

Three-dimensional body data has been used in many industry fields including the apparel industry. This research used data from a study of the changes in lower body girth measurements from a 3D scan study of 25 female subjects aged 18 to 24 in four postures; a standing posture, a $120^{\circ}$ knee bend posture, a one pace stepping posture, and a sitting posture with a $90^{\circ}$ knee bend. We used the information on the difference between standing and seated measurements to adjust ease values for pants patterns an evaluation of the appearance, and the comfort of the pants. Waist girth in the sitting posture increased 8% compared to a standing posture and the hip girth measurement increased 7%. A basic pants pattern (pants A) with 2.4cm ease at the waist and 2.6cm ease at the hip was developed and a pants pattern (pants B) was developed using the rates of lower body girth change with a 5.7cm ease (8% change) at the waist and 7cm ease (7% change) at the hip. The appearance assessment items of pants A in a standing posture were higher than pants B. On the other hand, most appearance assessment items of pants B in a sitting posture were higher than pants A, especially the ease of pants back waistline and the appearance of the whole back. Comfort assessment items of pants B in both standing and sitting postures were higher than the comfort assessment items for pants A, especially the location of pants waistline, the ease of pants at the waistline, and the ease at the abdomen. In order to find the best level of ease for better appearance and comfort in both standing and sitting postures, 20 pants were constructed with ease values at the waist and hip in increments of 1.1cm in the range between the ease values of pants A and pants B. A fit test was conducted to compare the average appearance and comfort ratings that identified the pants with the best ease values at the waist and hip. The highest total mean was achieved in the pants with a waist ease of 4.6cm and hip ease of 4.8cm.

• Corrosion Science and Technology
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• 제14권3호
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• pp.120-126
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• 2015

The usage of bending products recently have increased since many industries such as automobile, aerospace, shipbuilding, and chemical plants need the application of pipings. Bending process is one of the inevitable steps to fabricate the facilities. Induction heat bending is composed of compressive bending process by local heating and cooling. This work focused on the effect of induction heat bending process on the properties of ASME SA312 Gr. TP304 stainless steel pipes. Tests were performed for base metal and bended area including extrados, intrados, crown up, and down parts. Microstructure was analyzed using an optical microscope and SEM. In order to determine intergranular corrosion resistance, Double Loop Electrochemical Potentiokinetic Reactivation (DL-EPR) test and ASTM A262 practice A and C tests were done. Every specimen revealed non-metallic inclusion free under the criteria of 1.5i of the standard and the induction heat bending process did not affect the non-metallic inclusion in the alloys. Also, all the bended specimens had finer grain size than ASTM grain size number 5 corresponding to the grain sizes of the base metal and thus the grain size of the pipe bended by induction heat bending process is acceptable. Hardness of transition start, bend, and transition end areas of ASME SA312 TP304 stainless steel was a little higher than that of base metal. Intergranular corrosion behavior was determined by ASTM A262 practice A and C and DL-EPR test, and respectively step structure, corrosion rate under 0.3 mm/y, and Degree of Sensitization (DOS) of 0.001~0.075% were obtained. That is, the induction heat bending process didn't affect the intergranular corrosion behavior of ASME SA312 TP304 stainless steel.

• 대한기계학회논문집A
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• 제24권2호
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• pp.303-310
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• 2000

Fracture toughness of five different reactor pressure vessel steels was characterized in the transition temperature region by the ASTM E1921-97 standard method using Charpy-sized small specimens. T he predominant fracture mode of the tested steels was transgranular cleavage in the test conditions. A statistical analysis based on the Weibull distribution was applied to the interpretation of the scattered fracture toughness data. The size-dependence of the measured fracture toughness values was also well predicted by means of the Weibull probabilistic analysis. The measured fracture toughness transition curves followed the temperature-dependence of the ASTM master curve within the expected scatter bands. Therefore, the fracture toughness characteristics in the transition region could be described by a single parameter, so-called the reference temperature (T。), for a given steel. The determined reference temperatures of the tested materials could not be correlated with the conventional index temperatures from Charpy impact tests.

• 대한기계학회논문집A
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• 제34권1호
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• pp.55-60
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• 2010

틸팅형 고속열차의 차체에 적용되는 하니컴 복합재 조인트 구조물의 경우 운행중 외팔보형 굽힘하중을 받게된다. 하이브리드 복합재 조인트 구조물에 대한 굽힘시험평가를 수행하기 위해 실제 틸팅열차 차체 구조물에서 조인트부를 절단 채취하여 시험편으로 제작하였다. 굽힘시험결과 시험편의 파괴거동은 정적하중과 피로하중하에서 확연히 달라짐을 보였다. 정적굽힘하중 하에서는 하니컴 코어 영역에서 전단변형과 파괴가 발생하였으며, 피로굽힘하중 하에서는 복합재 표피층과 하니컴 코어층 사이에서 계면분리가 발생하거나, 또는 금속재 언더프레임과의 용접부에서 파괴가 발생하였다. 이러한 파괴거동은 다른 산업분야에서 사용되는 유사한 구조의 하니컴 복합재 조인트 구조물에서도 발생할 수 있기 때문에, 본 실험 결과를 하니컴 복합재 조인트 구조물의 설계변수를 개선하기 위해 이용될 수 있다.

• 대한의용생체공학회:의공학회지
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• 제19권5호
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• pp.433-441
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• 1998

본 연구에서는 전부도재관용 도재의 균열전파 양상과 구강환경이 파절강도에 미치는 영향을 평가하기 위해 시행되었다. 도재의 굽힘강도 늘 In-Ceram, IPS-Empress 및 VMK68의 순으로 나타났으며, 수중에서 좌다 기름중에서 더 놀은 강도를 보였다. 비커스 압자 압입부와 압입부를 중심으로 한 파면의 관찰 결과, VMK68 도재의 경우에는 9.8N의 압인하중하에서, IPS-Empress의 경우에는 47.0N의 압입하중하에서 교면에 median crack이 형성되는 양상을 보였으며, 균열이 압자의 압입시에 형성된 벽개면을 따라서 빠르게 성장하여 파괴에 도달한 양상을 보였다. In-Ceram의 경우에는 49.0h의 압임하중하에서 Palmqvlst clack이 형성되는 양상을 보였으며, 알루미나 입자에 의한 균열의 굴곡과 creak bridging으로 인한 강화기전이 관찰되었다.