• 한국정보과학회논문지:데이타베이스
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• 제27권1호
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• pp.42-52
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• 2000

서로 다른 보안등급을 가진 사용자들에 의해 공유되는 정보를 관리해야 하는 데이타베이스 시스템에서는 보안은 중요한 요구사항중 하나이다. 실시간 보안 데이타베이스 시스템은 데이타의 논리적인 정확성뿐만 아니라, 트랜잭션을 마감시간 내에 처리해야 하는 시간적인 제약조건과 데이타와 트랜잭션의 등급에 따라 데이타의 사용을 통제하고 상위 등급의 정보가 하위 등급으로 유출되는 것을 방지하여야 하는 보안 제약조건을 추가적으로 갖는다. 본 논문에서는 이러한 실시간 보안 데이타베이스 시스템의 요구사항을 만족시키는 동시성 제어 기법을 제안한다. 제안하는 프로토콜은 낙관적 기법에 기반을 두면서 상충되는 실시간 제약 조건과 보안 제약 조건을 모두 만족시키기 위해 다중 버전과 Mark기법을 사용한다. 제안된 프로토콜은 직렬성을 만족하며 로킹에 기반을 둔 프로토콜과의 모의실험 비교 결과 데이타 충돌이 많은 환경에서 우수한 성능을 보이고 있다.

• Progress in Superconductivity
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• 제4권1호
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• pp.42-47
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• 2002

Measuring magnetic fields with a SQUID sensor always requires preliminary adjustments such as optimum bas current determination and flux-locking point search. A conventional magnetoencephalography (MEG) system consists of several dozens of sensors and we should condition each sensor one by one for an experiment. This timeconsuming job is not only cumbersome but also impractical for the common use in hospital. We had developed a serial port communication protocol between SQUID sensor controllers and a personal computer in order to control the sensors. However, theserial-bus-based control is too slow for adjusting all the sensors with a sufficient accuracy in a reasonable time. In this work, we introduce programmatic control sequence that saves the number of the control pulse arrays. The sequence separates into two stages. The first stage is a function for searching flux-locking points of the sensors and the other stage is for determining the optimum bias current that operates a sensor in a minimum noise level Generally, the optimum bias current for a SQUID sensor depends on the manufactured structure, so that it will not easily change about. Therefore, we can reduce the time for the optimum bias current determination by using the saved values that have been measured once by the second stage sequence. Applying the first stage sequence to a practical use, it has taken about 2-3 minutes to perform the flux-locking for our 37-channel SQUID magnetometer system.

• 전기전자학회논문지
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• 제23권3호
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• pp.800-804
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• 2019

본 논문은 2.4 GHz 대역의 IoT용 주파수합성기를 위한 이중-루프 구성의 서브-샘플링 디지털 PLL을 소개한다. PLL은 초기에 주파수 분주기를 사용하는 coarse locking을 수행하며, 이 후 최종적으로는 주파수 분주기를 사용하지 않는 서브-샘플링 방식의 fine locking loop로 스위칭하게 된다. DTC를 사용하여 양자화 에러 제거를 수행하며 이를 통해 특정 타이밍 범위를 갖는 고해상도 TDC를 사용함으로써 낮은 인-밴드 위상잡음 특성을 가질 수 있다. 본 논문에서는 또한 coarse loop와 fine loop간의 위상 오프셋을 제거하기 위한 보정 회로를 제안하였다. Coarse locking이 진행되는 동안 fine loop의 위상 에러를 예측하고, 이를 다시 coarse loop에 보상함으로써 빠른 락킹 타임과 안정적인 동작을 확보하였다. 회로는 SystemVerilog 및 Verilog 언어로 모델링 및 Register-Transfer Level (RTL) 수준으로 설계 되었으며 시뮬레이션을 통해 충분히 그 동작이 검증되었다.

• 한국가구학회지
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• 제27권2호
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• pp.104-110
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• 2016

The aim of this study is to develop and suggest the handle for lockers according to the design process which are used for keeping of student's personal stuffs such as books, writing implements and gym uniform in elementary, middle and high school and university as well. This includes the design development for ILGUMTUR which is specialized for office furniture, but does not own the intellectual property right yet. The design concept based on the domestic locker market survey is recessed handle at low- to intermediate price and it's material should be plastic what is solid and light. The lock system should be constructed by molding process and the name plate can be exchanged every time the owner of locker changes. Contrary to the right angle of it's external appearance, the handle of the locker is designed to be softly round and the simplicity is pursued for an easy production. On the basis of this design concept the sketch has been drawn and upgraded in full by 3D-rendering. Then the mock-up has been completed by 3D printer and ILGUMTUR has obtained a patent for the locking system based on the rotation of 2 circles.

• International Journal of Automotive Technology
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• 제8권2호
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• pp.185-191
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• 2007

The new FMVSS 208, 213, 225 regulations include automatic suppression of airbags to prevent low-risk airbag deployment and the use of child seats with a rigid-bar anchor system. The regulations mean that children must sit in the rear seat, but do not include other specific safety measures for their protection. In the rear, restraint equipment consists of three-point shoulder/lap belts for the outside seats and a static two-point lap belt in the middle, with no additional devices such as pretensioners or load limiters; this is far from optimal for children. This study investigated injury rates using a 3-year-old-child dummy. ECE R44 sled tests used a booster, a speed of 48 km/h, and a 26- to 32-g rectangular deceleration pulse. While seated on a booster, the dummies were restrained by an adult shoulder/lap three-point belt. HIC_15 msec, Chest G and Nij were somewhat lower with an emergency locking retractor (ELR)+pretensioner+load limiter than with only an ELR or with ELR+pretensioner. However, the current seat-belt system results in injury rates that exceed the limit for OOP performance under the new FMVSS 208 regulations.

• 전자공학회논문지B
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• 제33B권3호
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• pp.62-68
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• 1996

A CMOS transmitter ASIC for the ATM switching system etc., was designed to transmit 155.52 Mbps serial data transformed from 19.44 Mbps parallel data. 155.52 MHz clock for synchronization of data is genrated using reference 19.44 MHz clock by an analog PLL while parallel to serial data conversion is done by a digital circuit. Circuit simulations confirm that PLL locking and data conversion are accomplished successfully. The area of the designed ASIC chip is 1.3${\times}1.0mm^2$. The locking time and the power consumption of the chip are about 600 nsec and less than 150 mW, respectively.

• 치과방사선
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• 제23권1호
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• pp.7-14
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• 1993

The Internal derangement of temporomandibular joint disc was evaluated by using magnetic resonance imaging and arthrogram in 5 patients having reciprocal clicking or locking and in 5 normal subjects. Parasagittal multisections on both closed and open mouth were serially obtained by using a 1.5 Tesla MR system and surface coil with CSMEMP, MPGR. MR images obtained were analized by correlating with images of arthrograms. The obtained results were as follows: 1. Displaced meniscus was clearly delineated as dark structure on MR images other than on arthrograms of closed mouth view of patient having clicking or locking. 2. The deltoid white images of synovial fluid were identified in the glenoid fossa and on the posterior surface of condyle on open mouth view and partly depicted on closed mouth view, of parasagittal sections by MPGR. 3. The greyish image of joint fluid was identified on the posterior surface of condyle on the open mouth view of parasagittal sections by CSMEMP. 4. The structural relationship among condyle, meniscus, and fluid showed the variety of images on each parasagitta1 view.

• ETRI Journal
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• 제18권3호
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• pp.161-170
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• 1996

We show that the electrically coupled Hindmarsh-Rose neuronal model exhibits various patterns of phase locking at fixed parameter value. Through the analysis of the effective coupling, the system is shown to be stabilized in one of these patterns according to the initial conditions. This corresponds to the parameter-tuning independent mode-switching mechanism that changes the electrical output of neuronal systems. It is also presented how the stable fixed points of the effective coupling which characterize the phase locking patterns depend on the external current.

• 한국정보통신학회:학술대회논문집
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• 한국해양정보통신학회 2001년도 추계종합학술대회
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• pp.640-643
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• 2001

최근 인터넷 사용의 급격한 확산으로 인해, 이제까지 전화망을 위주로 발전되어 왔던 통신망의 구조에 많은 변화가 일어나고 있다. 최근 우리나라에서도 지식 정보사회의 기반이 되는 초고속 정보통신망으로의 접속으로 발전되고 있으며, 이용 환경을 무선 방식으로 제공할 수 있는 30 GHz 주변 대역에서 BWLL 용 주파수를 할당하고 있다. 또한 실내용 초고속 무선 LAN, 차량 충돌 방지 시스템 등을 비롯한 Intelligent Transportation System, 그리고 국방 기술 둥 여러 분야에서 밀리미터파 대역 신호를 사용한 기술 개발이 요구되고 있다. 따라서, 본 논문에서는 이러한 밀리미터파를 생성하기 위한 여러가지 방법들을 설명하고, Sideband injection locking 방법을 제안하여 수치적인 컴퓨터 시뮬레이션을 통하여 그 가능성을 분석하였다.

• 한국복합재료학회:학술대회논문집
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• 한국복합재료학회 2000년도 추계학술발표대회 논문집
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• pp.173-176
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• 2000

Finite element model based on the Naghdi's shell theory in the general tensor-based form is formulated in the present study. Partial mixed variational functional for assumed strain is formulated in order to avoid the severe locking troubles known as transverse shear and membrane locking. The proposed assumed strain element in general tensor Naghdi's shell model provides very accurate solutions for thin shells in benchmark problems. In additions, linear elastic constitutive equations are given in the general curvilinear coordinate system including anisotropic layered structures. Thus laminated composited shell structures are easily analyzed in the present formulation.