• Journal of the Korean Applied Science and Technology
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• v.30 no.2
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• pp.244-250
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• 2013

We investigated green phosphorescent organic light-emitting diodes (PHOLEDs) with charge control layer (CCL) to produce high efficiency. The CCL and host material which was 4,4,N,N'-dicarbazolebiphenyl (CBP) of bipolar property can control the carrier movement in emitting layer (EML). The performance improvement by the insertion of CCL was realized to the well confined exciton and the reduced triplet exciton quenching effect in EML. Five types of devices (Device A, B, C, D, and E) were fabricated following the thickness of CCL within EML. The properties of device D using optimized thickness of CCL showed external quantum efficiency of 16.22% and luminous efficiency of 55.76 cd/A, respectively.

• Journal of Advanced Marine Engineering and Technology
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• v.40 no.7
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• pp.593-598
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• 2016

Static tests and low-cycle fatigue tests were conducted to analyze the characteristics of the bellows for LNG vessels according to the forming methods. The cycle life of bellows was tested based on the specified cyclic life, 80000 cycles, to analyze the difference in characteristics between pre-and post-test data by measuring the strain and stress of each convolution of formed bellows. The low-cycle fatigue test was conducted using a strain gauge that was attached to the convolution of bellows. Formed bellows were placed on the structural test device which was equipped with a hydraulic system and was capable of moving in the x-y direction. Data was measured and processed by a multi recorder. Through the static test and low-cycle fatigue tests results, the difference between the cycle life of bellows formed by mechanical methods and of those formed by hydraulic methods was investigated. Moreover, the cause of difference in cyclic life according to forming methods was performed.

• Proceedings of the Korean Vacuum Society Conference
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• 2011.08a
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• pp.167-167
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• 2011

한국표준과학연구원에서는 국제표준화기구에서 제정한 국제규격(ISO, PNEUROP, DIN, JIS, AVS 등)에 기반을 둔 터보분자펌프의 특성평가시스템을 자체적으로 설계/제작 하였고, 터보분자펌프 1,000 L/s 급의 Database를 구축하였다. 이것을 토대로 특성평가시스템의 신뢰성 확인과 Feedback을 통한 시제품 개발 및 평가지원을 위해 터보분자펌프 2,500L/s 급의 Database를 구축한다. 터보분자펌프의 배기성능을 나타내는 가장 중요한 항목인 배기속도는 분자류 영역에 따라 상이한 가스($N_2$, He)를 사용하여 Throughput method와 Orifice method 두 가지 방법을 병행하여 측정한다. 측정함에 있어서 측정게이지, 유량계 및 Orifice conductance의 불확도에 의하여 배기 속도에 많은 측정오차를 포함하고 있다. 측정 오차를 줄이기 위하여 1% 이상의 안정성과 4%의 오차만을 허용하는 자전 회전자게이지(SRG)와 $10^{-3}$ mbar-L/s 영역까지의 유량 주입범위를 가지는 불확도 ${\pm}$3%의 정적형 유량시스템(CVFM)을 사용하였다. Orifice method의 경우 고진공영역으로 진입할수록 커질 수밖에 없는 배기속도 측정 불확도를 최소화하기 위해 검증된 유량을 이용한 Conductance 값을 제시하여 두 방법에서 얻은 배기속도의 불연속적인 문제를 해결한다. 본 연구에서는 2,500 L/s 급 터보분자펌프는 무거운 기체 $N_2$와 가벼운 기체 He을 사용하여 압축비의 변화와 분자류 영역에 따른 배기속도 변화를 연구하고, 2,500 L/s 급 터보분자펌프의 측정능력을 검증한다. 차후에 배기속도뿐만 아니라 소비전력, 소음, 진동, 온도 등의 특성평가의 전반적인 사항을 평가하여 터보분자펌프 2,500 L/s 급의 database를 완비해간다. 터보분자펌프 특성평가시스템을 사용한 1,000 L/s 급과 2,500 L/s 급 특성 Data를 비교, 분석하여 신뢰성 파악 및 표준화 방안을 개발하고, 고진공펌프 개발 주체와의 feedback 지원 기능의 infra를 구축한다.

• Journal of the Institute of Convergence Signal Processing
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• v.11 no.3
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• pp.189-196
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• 2010

In this paper, we proposed the adaptive local sigma filter reducing noises generated by an image sensor. The small noises generated by the image sensor are amplified by increased an analog gain and an exposure time of the image sensor together with information. And the goal of this work was the system design that is reduce the these amplified noises. Edge data are extracted by Flatness Index Map algorithm. We made the threshold adaptively changeable by the luminance average in this algorithm that extracts the edge data not in high luminance, but just low luminance. The Local Sigma Filter performed only about the edge pixel that were extracted by Flatness Index Map algorithm. To verify the performance of the designed filter, we made the Window test program. The hardware was designed with HDL language. We verified the hardware performance of Local Sigma Filter system using FPGA Demonstration board and HD image sensor, $1280{\times}720$ image size and 30 frames per second.

• Journal of Biomedical Engineering Research
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• v.10 no.2
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• pp.139-150
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• 1989

A new motor-driven blood pump for artificial heart was developed. In this blood pump, a small size, high torque brushless DC motor was used as an energy converter and the motor rolls back and forth on a circular track. This movement of the "rolling-cyliner" causes blood ejection by alternately pushing left or right polyurethane blood sacs. This moving-actuator mechanism could be eliminate two potential problems of other motor-driven artificial hearts such as large size and poor anastomosis for the implantation. Theoretical analyses on the pump efficiency, the temperature rise, and the inflow mechanism were also performed. In a series of mock circulation tests, the theoretical analyses were compared to the measured hemodynamic and mechanical values. The pump system was shown to have sufficient cardiac output (upto 9 L/min), sensitivity to preload, and mechanical stability to be tested as an implantable total artificial heart.ial heart.

• Proceedings of the Korea Society for Industrial Systems Conference
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• 2001.05a
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• pp.165-183
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• 2001

지난해부터 인터넷 분야에서 가장 확실한 수익 모델을 갖춘 사업 분야로 e-Learning 분야가 손꼽히면서 많은 온라인 교육 서비스가 우후죽순처럼 등장해 이미 1,000여 개의 서비스가 각축을 벌이고 있다. 그러나 e-Learning은 무엇보다도 학습용 컨텐츠의 품질이 그 성패를 좌우한다 할 때 한국의 온라인 학습 컨텐츠의 품질은 부실하기 이를 데 없다는 게 중론이다. 이는 S/W 공학에서 S/W 품질 보장을 위해 개발 방법론이 중요한 것으로 인식되는 것과 이를 지원하기 위한 Method II등 여러 도구들이 보급되고 있는데 비해 학습 컨텐츠는 그 중요도와 개발이 복잡하고 정교함이 요구됨에도 불구하고 개발 방법론에 대한 인식과 개발방법론을 지원하기 위한 도구가 없음에 기인하는바 크다 할 수 있겠다. 아직까지 국내에서는 MacroMedia Director나 ToolBook, Authorware등 일반적인 저작 도구나 웹 기반의 컨텐츠를 제작하는 Dreamweaver등의 HTML Editor만 있으면 컨텐츠가 만들어 질 수 있는 것으로 착각하고 있는 경우가 많다. 교육 학습용 컨텐츠의 개발 주기를 살펴보면 요구 분석->교수 설계->저작->평가->배포의 단계를 거치게 되는데 이때 학습 컨텐츠의 품질은 사실 요구 분석과 교수 설계 단계에서 결정되게 되며 이 학습 컨텐츠의 품질을 결정하는 단계에서는 IT 분야 지식보다는 오히려 교육 공학적 지식이 더욱 요구된다. 그러나 현실적으로 이 단계의 절차적 복잡성과 전문성으로 인해 거의 대부분의 학습 컨텐츠들이 제대로 개발 주기를 거치지 못하고 검증되지 않은 스토리 보드에 의한 저작 단계로 바로 돌입하고 있는 것이 한국의 실정이라 하겠다. 따라서 본 프로젝트에 의해 개발 된 교수 설계 도구는 교육/학습 컨텐츠의 품질 보증을 위한 방법론인 교육 공학의 체제적 교수 설계 이론 Model (Instructional System Design Model), 특히 그 중에서도 이 분야의 사실상의 표준 이론(de facto standard)인 Dick & Carey 교수와 Gagne 교수의 인지주의 ISD Model을 기반으로 정교한 교수 설계와 코스 맵 설계를 가능하게 함으로써 학습 컨텐츠의 품질 보증 활동을 지원 할 수 있는 도구로 개발하였다. 특히 Linux 기반에서 PHP로 개발 함으로써 Platform에 구애받지 않은 사용 환경을 구현 하였으며 향후 많은 e-Learning Platform에 교수 설계 모듈로 장착 함으로써 기존의 e-Learning Platform들의 가치를 높일 수 있는 계기가 될 것으로 생각한다.

• Proceedings of the Korea Concrete Institute Conference
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• 2008.04a
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• pp.13-16
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• 2008

In a tension-controlled section, all steel tension reinforcement is assumed to yield at ultimate when using the strength design method to calculate the nominal flexural strength of members with steel reinforcement arranged in multiple layers. Therefore, the tension force is assumed to act at the centroid of the reinforcement with a magnitude equal to the area of tension reinforcement times the yield strength of steel. Because FRP materials have no plastic region, the stress in each reinforcement layer will vary depending on its distance from the neutral axis. Similarly, if different types of FRP bars are used to reinforce the same member, the stress level in each bar type will vary, and the member will show different behavior from our expectation. In this study, six high-strength concrete beam specimens reinforced with conventional steels, CFRP bars, and GFRP bars as flexural reinforcements were constructed and tested. The members reinforced with hybrid reinforcements showed higher stiffness, smaller crack width, and better ductility than the members reinforced with single type of FRP bars.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2016.05a
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• pp.791-793
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• 2016

In the development of various types of sensor technology, the general users smartphone, the environment is increased, which can be seen in contact with the movement recognition device, such as a console game machine (Nintendo Wii), an increase in the user needs of the action recognition-based input device there is a tendency to have. Mouse existing behavior recognition, attached to the outside, is mounted in the form of mouse button is deformed, the left mouse was the role of the right button and a wheel, an acceleration sensor (or a gyro sensor) inside to, plays the role of a mouse cursor, is to manufacture a compact, there is a difficulty in operating the button, to apply a motion recognition technology is used to operate recognition technology only pointing cursor is limited. Therefore, in this paper, using a MEMS-based motion-les Koguni tion sensor (Motion Recognition Sensor), to recognize the behavior of the two points of the human body (thumb and forefinger), to generate the motion data, and this to the foundation, compared to the pre-determined matching table (moving and mouse button events cursor), and generates a control signal by determining, were studied the generated control signal input device of the computer wirelessly transmitting.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.39 no.11
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• pp.1153-1159
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• 2015

Recently, synthetic biopolymers and bioceramics such as poly (${\varepsilon}$-caprolactone)(PCL), hydroxyapatite, tricalcium phosphate, biphasic calcium phosphate(BCP), and zirconia have been used as substrates to generate various tissues or organs in tissue engineering. Thus, the purpose of this study was the characterization of $ZrO_2$/BCP/PCL(ZBP) scaffold for bone tissue regeneration. Based on the result of single-line test, blended 3D ZBP scaffolds with fully interconnected pores and new complex pore pattern of $45^{\circ}+135^{\circ}$-type and staggered-type were successfully fabricated using a polymer deposition system. Furthermore, the effect of ZBP scaffold on mechanical property was analyzed. In addition, in vitro cell interaction of ZBP scaffold on MG63 cells was evaluated using a cell counting kit-8(CCK-8) assay.

• Journal of the Korean Society of Propulsion Engineers
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• v.14 no.2
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• pp.19-28
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• 2010

Generally, combustion instability is generated by the mutual coupling between the heat release and the acoustic pressure in the combustor. On the occasion, the acoustic pressure generates the oscillation of the mass flow rate of propellant injected from injector, and this oscillation again affects combustion in the combustor. So, the dynamic characteristics of the injector have been studied to control combustion instability using injector itself in Russia from 1970's. In order to study injector dynamics, a mechanical pulsator for forced pressure pulsation is produced and the method to quantify the mass flow rate of the propellant that is oscillating at the exit of the injector is developed. With the pulsator and the method, pulsating values of the mass flow rate, pressure, liquid film thickness, and axial velocity generated at the exit of the simplex swirl injector are measured in real time. And phase-amplitude characteristics of each parameter are analyzed using these pulsating values acquired at the exit of the simplex swirl injector.