• 한국콘텐츠학회논문지
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• 제6권1호
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• pp.8-13
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• 2006

본 논문에서는 모바일 단말기의 키 버튼을 누르면 발생되는 DTMF 신호를 이용하여 자동 도어락 시스템을 제안하고 구현한다. 모바일 단말기의 DTMF신호처리를 위하여 이 시스템은 송신기 모듈과 수신기 모듈로 구성된다. 이어폰 잭으로 연결된 모바일 단말기의 DTMF신호들은DTMF수신기의 입력단자로 들어가서 4비트 형식을 갖는 부호변환기에 의해 이진신호로 부호화된다. 부호화된 출력신호들은 ASK 송신기 모듈로 전송되고 RF신호로 변조되어 자유공간으로 전파된다. 자유공간을 통하여 전달된 RF신호들은 수신기모듈인 ASK복조기에 의해 복조되고 MCU로 보내진다. MCU에 의해서 처리된 출력신호들은 이미 프로세서 내에 기록된 비밀번호와 비교되고 파워릴레이로 전달된다. 만약 비교된 결과 값이 일치하면 자동 도어락 시스템은 도어를 열게 되고 그 반대의 경우에는 도어를 닫은 상태를 유지한다. 본 논문에서 구현된 자동 도어락 시스템은 무선 환경에서 잘 동작한다.

• 접착 및 계면
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• 제7권4호
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• pp.10-12
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• 2006

The successful use of adhesively bonded parts depends on the defect-free bond of the components. Therefore it is necessary to detect relevant faults and defects in an early state of the production. A 100% test should be pursued, but especially at complicated structures the detection of defects is not easy. Possible testing methods, which show a high potential for the NDT of adhesively bonded parts, are thermography based NDT methods. At present mainly two different procedures of active thermography are being used: Pulse and Lock-In Thermography. With pulse thermography the examined material is warmed up with a short energy pulse (light, eddy current or ultrasonic pulse) and the heat response is recorded after a certain time. The result is an infrared image which indicates material defects in different depths. This paper presents a variety of images showing the capability of Lock-In Thermography to image subsurface defects. Several examples of adhesives joints qualify the ultrasonic Lock-In-Thermography for the in-process quality control for adhesive bonded components.

• 대한기계학회논문집B
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• 제26권4호
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• pp.515-523
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• 2002

Effects of rotary oscillation on unsteady laminar flow past a circular cylinder have been investigated in this study. Numerical simulations are performed for the flow at Re=100 in the range of 0.2<$\Omega$<2.5 and 0.02<$St_f$<0.8, where $\Omega$ and $St_f$ are, respectively, the maximum rotation velocity and rotation frequency normalized by the free-stream velocity and cylinder diameter. Results show that rotary oscillation has significant effects on the flow. When the rotation frequency is near the natural vortex-shedding frequency, lock-on occurs and the lock-on frequency range becomes wider as the rotation velocity increases. In a certain range of the rotation frequency and velocity, modulations in the velocity, lift and drag signals occur and this modulation frequency is expressed as a linear combination of the rotation frequency and vortex-shedding frequency. The mean drag and amplitude of the lift fluctuations show local minima near the boundary between the lock-on non and lock-on regions.

• 한국항해학회지
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• 제21권1호
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• pp.13-31
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• 1997

Being situated at the key point of northeast asia, the port of Inchon as an entrance to the captial city, Seoul is expected to play in marine transportation in Korean Pennisular on the verge of its reunification. In this thesis, inner-lock physical disstribution system of the port was analyzed, which treats more than 82% of total incoming and outgoing cargoes. The overall findings are as follows; 1. In thet viewpoint of physical distribution system of the port, it takes disadvantages of accessing to inner lock berth due to such natural restrictions as tides, passing the lock and so on. And insufficient port facilities as a whole, causes delay in quay-handling, transfer and storage, also facing with serious congestion in inland transport on the road. 2. It was revealed that the port facilities are insufficient yet in spite of its improved productivity by means of raising the effectiveness of port operation and of installing advanced cargo handling facilities. 3. In order to enhance the effectiveness of inner port physical distribution system , the improvement of lock facilities, expansionof port facilities and more effective terminal operating system are crucial. 4. To ensure the measures to solve the above problem, existent outer-lock ports such as Inchon Sourthern-port and Northern-port are necessary to be redeveloped more positively , otherwise a new port at outskirt of the city should be developed to ensure free connection to inland transportation.

• 한국정보통신학회:학술대회논문집
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• 한국정보통신학회 2015년도 추계학술대회
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• pp.560-563
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• 2015

기존에 사용되어지는 도어락 시스템은 키 또는 카드, 패드를 이용하는 방식으로 복제, 분실, 훼손 등의 위험과, 타인에게 노출되는 문제점을 가지고 있다. 본 논문에서는 기존의 도어락 시스템 문제점을 보완하고자 스마트폰에 내장된 Bluetooth통신과 OTP(One-Time-Password), Hide-Key 인증방식 및 Arduino를 활용한 스마트폰 기반의 무선 OTP 도어락 시스템 설계 및 구현함으로써 사용자들은 보안 및 노출의 위험성에서 벗어나 보다 편리하고 안전한 생활을 가능하게 한다.

• 한국해양공학회지
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• 제23권1호
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• pp.74-80
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• 2009

In this study, the static and modal analyses to find the characteristic of eigenvalues for a towed cable were with a free boundary condition at the bottom end carried out with numerical study. The resulting numerical code with finite element method was used to study sample problems for a cable with towing speeds. After tracing the equilibrium state with a towing speed through the static analysis, modal analysis on the basis of static results was performed. The static top tension for a critical towing speed is nearly 50 percent of what it was for a free hanging pipe. From static analyses, it is found that towing speed has a noticeable effect on top tension of a towed pipe. At a high towing speed, differences between the first and second periods become larger. Compared to the fundamental period for a free hanging pipe, that for a towed pipe with a critical towing speed is approximately 1.4 times larger. This result is very important point in that the lock in condition and tension of the towed cable system with top excitation can be predicted. The corrected close form solution to solve natural periods for a towed cable was presented in this study. The code is validated by comparison of the results of theoretical and numerical studies. Two results were in very good agreement. This study can contribute to predicting the lock-in condition and tension for a towed cable or pipe with top excitation.

• 대한조선학회논문집
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• 제43권3호
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• pp.322-330
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• 2006

Numerical calculations are carried out for flow past a circular cylinder forced oscillating normal to the free-stream flow at a fixed Reynolds number equal to 185. The cylinder oscillation frequency ranged from 0.8 to 1.2 of the natural vortex-shedding frequency, and the oscillation amplitude extended up to 20% of the cylinder diameter. IBM (Immersed Boundary Method) with direct momentum forcing was adopted to handle both of a stationary and an oscillating cylinder Present results such as time histories of drag and lift coefficients for both stationary and oscillating cases are in good agreement with previous numerical and experimental results. The instantaneous wake patterns of oscillating cylinder with different oscillating frequency ratios showed the synchronized wakes pattern in the lock-in region and vortex switching phenomenon at higher frequency ratio than the critical frequency ratio.

• 대한기계학회논문집B
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• 제31권8호
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• pp.702-710
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• 2007

Direct numerical simulation (DNS) is performed to investigate suppressed wake transition and occurrence of lock-on in the wake of a circular cylinder disturbed by sinusoidal perturbation at the Reynolds number of 220 (A-mode instability regime). The sinusoidal perturbation, of which the frequency is near twice the natural shedding frequency, is superimposed on the free stream velocity. It is shown that the wake transition behind the circular cylinder can be suppressed due to the perturbation of the free stream velocity. This change causes a jump in the Strouhal number from the value corresponding to A-mode instability regime to the value corresponding to retarded wake transition regime (extrapolated from laminar shedding regime) in the Strouhal-Reynolds number relationship. As a result, vortex shedding frequency is locked on the perturbation frequency depending not on the natural shedding frequency but on the modified shedding frequency.

• 한국컴퓨터정보학회논문지
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• 제27권4호
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• pp.1-8
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• 2022

이 논문에서는 싱글 프로세스 멀티코어 환경의 매크로 확장에서 Lock이 필요하지 않은 더 효과적인 고유식별자 할당 방식을 제안한다. 이 할당 방식의 핵심 아이디어는 나머지 연산을 이용해 순차적 의존성을 제거하는 것이다. 우리가 고안한 방식이 멀티코어 병렬 환경에서 매크로 확장의 성능 개선에 적합함을 확인하기 위해, 기존에 순차적 방식의 고유식별자 생성으로 구현된 라이브러리를 우리가 고안한 방식으로 변경하여 변경 전의 버전과 후의 버전의 라이브러리로 작성된 같은 프로그램의 성능을 비교하는 벤치마크를 수행하였다.

• 한국정보처리학회:학술대회논문집
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• 한국정보처리학회 2010년도 추계학술발표대회
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• pp.1721-1724
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• 2010

멀티코어의 등장과 병렬 프로그래밍의 확산으로 lock-free 동기화 기법에 대한 관심과 필요성이 더욱 커지고 있지만, 대부분의 lock-free 동기화 기법들이 구현 복잡도와 동작시 오버헤드로 인해 실제 활용되는 사례는 미비하다. 하지만, RCU(Read-Copy Update) 기법의 등장으로 다양한 운영체제에서 이를 구현하여 활용하고, 최근에는 게임 서버와 같은 응용 프로그램에서도 이를 활용하려는 시도가 늘어나고 있지만, 기존에 제안된 URCU(Userspace RCU) 기법들은 메모리 순서오류 문제 해결을 위한 메모리 장벽 호출 및 reader와 updater 간의 IPC 등으로 충분한 성능을 보여주지 못하고 있다. 이에 본 논문에서는 페이지 폴트를 이용한 URCU 기법을 제안하고, 이를 구현하여 기존의 URCU 기법들과 실험을 통하여 평가하였다.