• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2005년도 추계학술대회논문집
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• pp.159-163
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• 2005

A dynamic vibration absorber using the Zener's model has been taken into account with respect to frequency response characteristics. The concept of the tuned mass damper with a single degree of freedom has been well applied for many industrial fields, because many researchers have extensively studied various basic characteristics, performance and optimization methods for long time. The Zener's model has an additional spring, which is connected between a damper and a mass, while the tuned mass damper with a single degree of freedom consists of a mass, a spring and a damper connected in parallel. In previous works, the basic performance and characteristics of the Zoner's model as a dynamic vibration absorber have not been investigated. In this study, the frequency response characteristics according to the parameter change of the Zener's model have been described. In order to find the optimum value of several parameters, we use iterative scheme with three dimensional frequency response diagram by MATLAB programming. Present results shows the Zener's model can give more good damping performance than the simple tuned mass damper, and the numerical of optimization method should be developed for the efficient vibration absorbtion.

• 대한교통학회지
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• 제24권5호
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• pp.45-56
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• 2006

우리나라 철도산업의 생산특성과 효율성에 관하여 충분히 검토된 양질의 정보가 축적되기 위해서는 다양한 각도에서 다양한 방법으로 검토가 필요하다. 본 논문에서는 거리함수를 이용한 우리나라 철도산업의 생산특성 및 기술효율성 분석결과를 제시한다. Shephard(1953)가 처음 소개한 거리함수는 가격에 관한 정보를 필요로 하지 않는다. 따라서 가격에 관한 자료를 구하기 어렵거나 또는 공공부문의 경우처럼 가격에 대한 통제가 존재하는 상황에서 효과적인 분석수단이 될 수 있다. 또한 다수투입 다수산출 생산기술을 다룰 수 있으며 생산특성과 효율성을 동시에 분석할 수 있는 장점을 갖고 있다. 한국철도의 1963년부터 2004년까지의 연도별 자료로부터 이차계획법모형을 사용하여 거리함수를 추정하였다. 추정된 기술효율성은 1980년 이후 2004년까지 점진적으로 개선되고 있는 것으로 나타났다. 간접 Morishima대체탄력성 추정결과는 노동을 다른 투입으로 대체하는 것이 매우 어렵거나 또는 불가능한 것으로 나타났다. 평균 규모탄력성은 2.7로 나타났으며 이는 규모를 1%증가시켰을 때 산출이 2.7%증가함을 의미한다. 즉 한국철도에 규모의 경제가 존재함을 의미한다.

• 한국항공우주학회지
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• 제30권4호
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• pp.44-52
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• 2002

비정상, 비압축성 Navier-Stokes 코드를 이용하여, 저 레이놀즈수 유동에서 flapping 운동을 하는 익형의 공력특성을 수치해석적인 방법으로 연구하였다. 비정상 유동장의 효율적인 계산을 위하여, 개발된 코드는 MPI 프로그래밍 기법을 이용하여 병렬처리 되었으며, 난류 유동장의 계산을 위해 2방정식 난류모델의 하나인 k-$\omega$ SST 모델을 적용하였다. 익형의 3가지 운동모드 즉, pitching, plunging, flapping과 주파수 및 진폭의 변화 그리고 두께와 캠버의 변화에 의한 공력특성을 살펴보았고, 이를 위해 NACA4자 계열의 익형을 이용하였다. 해석 결과는 실험치와 비교하여 보았을 때 잘 일치하였으며, 각 운동모드에서의 공기역학적 특성을 파악할 수 있었다.

• Journal of Electrical Engineering and Technology
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• 제9권6호
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• pp.1928-1934
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• 2014

Induction motors are widely used due to their rugged, robust and easy to care features. Since they are heavily used in industry, testing of three phase induction motors have play a vital role. In order to determine motor equivalent circuit parameters, efficiency of motor, squirrel caged laboratory sized an induction motor test setup is prepared. It is suitable for the induction motor with the frame size of 100 and 112. A virtual Instrumentation typed engineering workbench (called as LabVIEW) software packet, is utilized as a graphical user interface program. Motor input power is measured by measuring the input voltage, current and power factor with the help of hall effect typed voltage and current transformers. Also, the output power is measured by measuring the speed and torque with the help of an encoder and torque sensor. All outputs of the voltage and current transformer, encoder and temperature, torque sensors are given to the Data Acquisition Card (DAQ) which acquires the data for processing and then the equivalent circuit parameters, efficiency, performance and loading characteristics are found out, using LabVIEW based user interface. It is suggested to use this test rig for the quality control of produced motors in industry, and an educational experiment setup in the school laboratories.

• 정보처리학회논문지D
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• 제11D권7호
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• pp.1443-1450
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• 2004

객체지향 소프트웨어 개발 초기단계에서 클래스의 결정은 많은 객체와 관련된 속성들의 클러스터링을 하는 복잡한 문제이다. 클래스의 재사용을 위해 라이브러리에 클래스의 등록은 반복적인 시행착오에 의존하여왔다. 클래스를 등록하는 전통적인 방법과 모델링 혹은 설계단계에서 클래스와 그 계층구조의 정의를 위한 통합적인 방법에 대해 논의한다. 속성 클러스터링 문제를 위해 객체들의 속성 유사도에 근거하여 0-1 정수프로그램 위한 모형을 제시하고 또한 네트워크 기법을 이용한 클러스터링 알고리즘을 제안한다. 클래스 계층구조를 생성하기 위한 규칙을 제시하였으며 계층구조그래프 생성알고리즘을 제안한다. 본 연구결과를 이용하여 실제 현장의 문제를 사례로 제시한다.

• 한국전기전자재료학회논문지
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• 제15권7호
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• pp.576-582
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• 2002

Nonvolatile semiconductor memory devices with reoxidized nitrided oxide(RONO) gate dielectrics were fabricated, and nitrogen distribution and bonding species which contribute to memory characteristics were analyzed. Also, memory characteristics of devices depending on the anneal temperatures were investigated. The devices were fabricated by retrograde twin well CMOS processes with $0.35\mu m$ design rule. The processes could be simple by in-situ process in growing dielectric. The nitrogen distribution and bonding states of gate dielectrics were investigated by Dynamic Secondary Ion Mass Spectrometry(D-SIMS), Time-of-Flight Secondary Ion Mass Spectrometry(ToF-SIMS), and X-ray Photoelectron Spectroscopy(XPS). As the nitridation temperature increased, nitrogen concentration increased linearly, and more time was required to form the same reoxidized layer thickness. ToF-SIMS results showed that SiON species were detected at the initial oxide interface which had formed after NO annealing and $Si_2NO$ species within the reoxidized layer formed after reoxidation. As the anneal temperatures increased, the device showed worse retention and degradation properties. It could be said that nitrogen concentration near initial interface is limited to a certain quantity, so the excess nitrogen is redistributed within reoxidized layer and contribute to electron trap generation.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2008년도 추계학술대회 논문집 Vol.21
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• pp.7-8
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• 2008

The memory characteristics of charge trap flash (CTF) with $HfO_2$ charge trap layer were investigated. Especially, we focused on the effects of tunnel barrier engineering consisted of $SiO_2/Si_3N_4/SiO_2$ (ONO) stack or $Si_3N_4/SiO_2/Si_3N_4$ (NON) stack. The programming and erasing characteristics were significantly enhanced by using ONO or NON tunnel barrier. These improvement are due to the increase of tunneling current by using engineered tunnel barrier. As a result, the engineered tunnel barrier is a promising technique for non-volatile flash memory applications.

• 한국공간구조학회논문집
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• 제5권3호
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• pp.123-130
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• 2005

본 연구에서는 횡하중을 받는 아웃리거 시스템의 횡변위를 정량적으로 제어할 수 있는 효율적인 강성최적설계기법을 제시하고 이를 이용하여 아웃리거 시스템의 거동특성 및 효율성을 평가하고자 한다. 이를 위해 아웃리거를 이용한 고층 구조물의 거동특성을 고려한 민감도 해석을 수행하며 아울러 수학적계획법의 일반성을 유지하면서도, 큰 규모의 문제도 효율적으로 다룰 수 있는 근사화 개념을 도입하여 구속조건식을 설정한다. 특히 초기에 주어진 단면형상이 최적설계 과정동안 계속 유지된다는 가정을 이용하여 부재재설계 기법을 개발한다. 제시된 정량적인 횡변위 제어 방안의 효용성을 검토하기 위해 네 가지 형태의 50층 고층구조물 예제가 고려된다.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2001년도 추계학술대회 논문집
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• pp.17-20
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• 2001

Nonvolatile semiconductor memory devices with reoxidized nitrided oxide(RONO) gate dielectric were fabricated, and nitrogen distribution and bonding species which contributing memory characteristics were analyzed. Also, memory characteristics of devices according to anneal temperatures were investigated. The devices were fabricated by 0.35$\mu\textrm{m}$ retrograde twin well CMOS processes. The processes could be simple by in-situ process of nitridation anneal and reoxidation. The nitrogen distribution and bonding state of gate dielectric were investigated by Dynamic Secondary Ion Mass Spectrometry(D-SIMS), Time-of-Flight Secondary ton Mass Spectrometry(ToF-SIMS), and X-ray Photoelectron Spectroscopy(XPS). Nitrogen concentrations are proportional to nitridation anneal temperatures and the more time was required to form the same reoxidized layer thickness. ToF-SIMS results show that SiON species are detected at the initial oxide interface and Si$_2$NO species near the new Si-SiO$_2$ interface that formed after reoxidation. As the anneal temperatures increased, the device showed worse retention and degradation properties. These could be said that nitrogen concentration near initial interface is limited to a certain quantity, so excess nitrogen are redistributed near the Si-SiO$_2$ interface and contributed to electron trap generation.

• 센서학회지
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• 제22권4호
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• pp.292-296
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• 2013

The ultrasonic wind sensor that pass through the air, beating the delivery of ultrasonic wind speed increases or decreases by the physical characteristics of the wind speed and the direction of the sensor, the transmission and reception of ultrasonic time difference measured by a two-axis vector wind and wind speed measured by calculating a device that converts the digital signal is Anemometer and wind direction meteorological facilities management, management of the ship sail used for various purposes, including, but used the existing 3-cup (mechanical) anemometer wind rotor caused by mechanical wear parts replacement due to the short-term, the reliability of the product is low, parts replacement, and according to the characteristics caused the car, there is a problem in high maintenance costs. In addition, because the bearings use of the marine environment and the cryogenic environment was constrained. In this study, the excellent long-term reliability, using ultrasonic-type environment that is not constrained to produce wind anemometer located $90^{\circ}$ conformal road using four piezoelectric sensors were fabricated structures, the piezoelectric oscillator circuit produces a rash and receiving transmit and receive speeds the car through the two-axis vector calculation to measure wind velocity processor firmware programming, and its characteristics were tested.