• 한국광학회지
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• 제16권4호
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• pp.297-303
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• 2005

우리는 $^{87}Rb$ 원자의 $5S_{1/2}-5P_{3/2}-4D_{3/2,\;5/2}$ 전이선을 이용하여 레이저의 세기, 편광조합, 그리고 정렬상태에 따른 이중공명광펌핑(double resonance optical pumping; DROP) 스펙트럼을 조사하였다. $5P_{3/2}-4D_{5/2}$ 전이선에서 레이저의 세기에 따른 초미세 구조간의 DROP 신호의 변화가 크게 나타났고, 그 원인은 순환전이선의 낮은 광펌핑 효율 때문이었다. 두 레이저의 편광조합을 달리 했을 때 이중공명의 전이율이 변하고, 이러한 효과가DROP스펙트럼의 변화로 나타났다. 또한 두 레이저가 같은 방향으로 진행하는 경우와 반대 방향으로 진행하는 경우를 비교했을 때, 스펙트럼의 선폭은 각각 12.2 MHz 와 6.9 MHz로 측정되었다.

• 한국전자파학회논문지
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• 제30권1호
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• pp.38-44
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• 2019

본 논문에서는 자기 공진형 무선전력전송 시스템에서 사용 가능한 핑거프린트 방식의 측위 기법을 제안하고 성능을 검증하였다. 측위를 위해 3축 방향의 자기장 신호 측정이 가능한 소형 직교 보조코일을 가지는 수신기 코일 설계 방안을 제시하고, 제안한 코일을 이용해 획득한 3축의 기전력의 크기와 위상 특성을 추출하였다. 측정 지점에서 획득된 값을 이용하여 위치를 측정하기 위해 LUT(Look-up Table)를 이용하는 기법과 기계학습 방식 중 LDA(Linear Discriminant Analysis)을 이용하는 기법을 제안하고, 각 기법별 측위 정확도 및 계산 속도를 비교 제시하였다. 6.78 MHz 무선전력전송시스템에서 75개의 지점을 측위하는 실험에서 제안하는 코일과 기전력 특성을 이용한 LUT 기법을 적용하여 측위 정확도 97.33%를 달성하였다. LDA 기법의 경우, 기전력과 위상을 이용하여 측위하는 경우 LUT 기법에 비해 계산 속도가 늘어나지만 정확도를 향상시킬 수 있었다.

• 인터넷정보학회논문지
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• 제20권4호
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• pp.63-72
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• 2019

기업 혹은 조직 거버넌스의 하위개념인 비즈니스 거버넌스와 IT 거버넌스는 학계에서 주요 연구과제가 되어 왔다. 그러나 비즈니스와 IT 도메인의 매개적 구조체로서 프로세스의 중요성에도 불구하고, 프로세스 거버넌스(PG)의 연구는 상대적으로 미흡하였다. PG는 비즈니스 전략을 IT시스템 구현과 연계하는 활동에 집중하며, 기업의 본원적 가치 창조 활동을 설명한다. 본 논문은 정치학, 사회학, 행정학에서의 기본적인 거버넌스 개념을 연구하고, 거버넌스 유형을 6개의 카테고리로 분류했다. 그리고 PG에 대한 일련의 메타모델을 제안한다. 예를 들면 전통적인 핸더슨과 벤카트라만의 SAM모델을 수정한 neo-SAM 모델, 조직 거버넌스 네트워크 모델, 조직거버넌스 순차모델, 조직 거버넌스 메타모델, 프로세스 거버넌스 큐브 모델, COSO와 프로세스 거버넌스의 비교 모델, 마지막으로 프로세스 거버넌스 프레임워크 등이다. SAM모델과 neo-SAM 모델의 주요한 차이점은 비즈니스 거버넌스와 IT 거버넌스 사이에 프로세스 거버넌스 도메인을 포함한 것이다. 여러 개의 메타 모델 중에서, 프로세스 거버넌스 프레임워크가 핵심 개념 모델로서 이는 4개의 활동차원 - 전략연계, 권한강화, 직능향상, 자율조직 - 으로 구성된다. 연구자는 각 활동차원 별로 5개씩 총 20개의 변인을 설계했다. 4개의 활동차원 외에도 프로세스 거버넌스 사이클을 움직이는 6개의 순환 동력 - 탈규범력, 미시권력, 활력, 자기조직력, 규범력, 센스메이킹 - 이 있다. 4개의 활동차원과 6개의 동력으로 조직은 내외부의 환경 변화에 대한 프로세스 거버넌스의 융통성을 유지할 수 있다. 본 연구는 프로세스 거버넌스 역량 모델과 프로세스 거버넌스 변인을 제안하는 목적을 가진다. 업계환경은 기능 중심 조직관리에서 프로세스 중심 관점으로 변화하고 있다. 연구자가 제안하는 프로세스 거버넌스 프레임워크가 향후 프로세스 거버넌스 도메인의 연구 확산을 위한 맥락적 참조모델과 아울러 프로세스 거버넌스 측정도구의 개발을 위한 조작적 정의의 틀을 제공할 것이다.

• ETRI Journal
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• 제25권3호
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• pp.179-186
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• 2003

Using biometrics to verify a person's identity has several advantages over the present practices of personal identification numbers (PINs) and passwords. At the same time, improvements in VLSI technology have recently led to the introduction of smart cards with 32-bit RISC processors. To gain maximum security in verification systems using biometrics, verification as well as storage of the biometric pattern must be done in the smart card. However, because of the limited resources (processing power and memory space) of the smart card, integrating biometrics into it is still an open challenge. In this paper, we propose a fingerprint verification algorithm using a multi-resolution accumulator array that can be executed in restricted environments such as the smart card. We first evaluate both the number of instructions executed and the memory requirement for each step of a typical fingerprint verification algorithm. We then develop a memory-efficient algorithm for the most memory-consuming step (alignment) using a multi-resolution accumulator array. Our experimental results show that the proposed algorithm can reduce the required memory space by a factor of 40 and can be executed in real time in resource-constrained environments without significantly degrading accuracy.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2003년도 ICCAS
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• pp.237-240
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• 2003

Gas turbines are extensively used in flight propulsion, electrical power generation, and other industrial applications. During its life span, a turbine blade is taken out periodically for repair and maintenance. This includes re-coating the blade surface and re-drilling the cooling holes/channels. A successful laser re-drilling requires the measurement of a hole within the accuracy of ${\pm}0.15mm$ in position and ${\pm}3^{\circ}$ in orientation. Detection of gas turbine blade/vane cooling hole position and orientation thus becomes a very important step for the vane/blade repair process. The industry is in urgent need of an automated system to fulfill the above task. This paper proposes approaches and algorithms to detect the cooling hole position and orientation by using a vision system mounted on a robot arm. The channel orientation is determined based on the alignment of the vision system with the channel axis. The opening position of the channel is the intersection between the channel axis and the surface around the channel opening. Experimental results have indicated that the concept of cooling hole identification is feasible. It has been shown that the reproducible detection of cooling channel position is with +/- 0.15mm accuracy and cooling channel orientation is with +/$-\;3^{\circ}$ with the current test conditions. Average processing time to search and identify channel position and orientation is less than 1 minute.

• Journal of Computational Design and Engineering
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• 제3권3호
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• pp.286-294
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• 2016

In this paper we present an efficient technique for sketch-based 3D modeling using automatically extracted image features. Creating a 3D model often requires a drawing of irregular shapes composed of curved lines as a starting point but it is difficult to hand-draw such lines without introducing awkward bumps and edges along the lines. We propose an automatic alignment of a user's hand-drawn sketch lines to the contour lines of an image, facilitating a considerable level of ease with which the user can carelessly continue sketching while the system intelligently snaps the sketch lines to a background image contour, no longer requiring the strenuous effort and stress of trying to make a perfect line during the modeling task. This interactive technique seamlessly combines the efficiency and perception of the human user with the accuracy of computational power, applied to the domain of 3D modeling where the utmost precision of on-screen drawing has been one of the hurdles of the task hitherto considered a job requiring a highly skilled and careful manipulation by the user. We provide several examples to demonstrate the accuracy and efficiency of the method with which complex shapes were achieved easily and quickly in the interactive outline drawing task.

• Journal of Korean Neurosurgical Society
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• 제53권1호
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• pp.49-51
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• 2013

A case of traumatic spondyloptosis of the cervical spine at the C6-C7 level is reported. The patient was treated succesfully with a anterior-posterior combined approach and decompression. The patient had good neurological outcome after surgery. A-51-year-old female patient was transported to our hospital's emergency department after a vehicle accident. The patient was quadriparetic (Asia D, MRC power 4/5) with severe neck pain. Plain radiographs, computerize tomography and spinal magnetic resonance imaging (MRI) showed C6-7 spondyloptosis and C5, C6 posterior element fractures. Gardner-Wells skeleton traction was applied. Spinal alignment was reachived by traction and dislocation was decreased to a grade 1 spondylolisthesis. Then the patient was firstly operated by anterior approach. Anterior stabilization and fusion was firstly achieved. Seven days after first operation the patient was operated by a posterior approach. The posterior stabilization and fusion was achieved. Postoperative lateral X-rays and three-dimensional computed tomography showed the physiological realignment and the correct screw placements. The patient's quadriparesis was improved significantly. Subaxial cervical spondyloptosis is a relatively rare clinical entity. In this report we present a summary of the clinical presentation, the surgical technique and outcome of this rarely seen spinal disorder.

• 한국철도학회논문집
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• 제9권2호
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• pp.187-192
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• 2006

The regularity of railway track alignment is a crucial component fur maintaining travel safety and the smoothness of passenger ride. The conventional spectral analysis has been considered to estimate the severity of the track irregularity from measured data. The time domain data used to be changed into the frequency domain by Fourier transform. Because the measuring points can be regarded as the time points, the spatial-frequency can be introduced instead of the time-frequency. Although FFT(Fast Fourier Transform) and/or PSD(Power Spectral Density) function could provide fairly localized information within frequency domain, but chronical configurations of data could be missed. In this study, we attempt to apply the Morlet wavelet transform for the purpose of a frequency-time-domain analysis rather than a frequency-domain analysis. The applicability of wavelet transform is examined for the estimation of the track irregularity with real measured track data on the section of Kyoung-bu line by EM-120 measuring vehicle. It is shown that the wavelet transform can be an effective tool to manage the track irregularity.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2001년도 춘계학술대회 논문집
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• pp.865-868
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• 2001

We designed and fabricated a planner-type thermoelastic microactuator with a latch-up operation for optical switching. Latch-up actuation is prerequisite to implement an optical switch with low power consumption and high reliability. The proposed microactuator consists of four cantilever-shaped thermal actuators, four displacement linkages, two shallow arch-shaped leaf springs, a mobile shuttle mass with a micromirror, and four elastic boundaries. The structural layer of the planar microactuator is phosphorous-doped 12$\mu\textrm{m}$-thick polysilicon, and the sacrificial layer is LTO(Low Temperature Oxide) of 3$\mu\textrm{m}$thickness. The displacement of actuator is as large as 3$\mu\textrm{m}$when the length of actuation bar is 100$\mu\textrm{m}$in length at 5V input voltage. The proposed microactuators have advantages of easy assembly with other optical component by way of fiber alignment in the substrate plane, and its fabrication process features simplicity while retaining batch-fabrication economy.

• Journal of Advanced Marine Engineering and Technology
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• 제3권1호
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• pp.2-18
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• 1979

Due to increasing ship dimensions and installed propulsive power, resonance frequencies of the propeller shaft system tend to decrease and they can appear in some cases within the operating range of the shaft revolution. For calculation of transverse shaft vibrations, various methods have been proposed but as they are mainly for approximate calculation, no contented results are obtained. For fairly accurate estimation of resonance frequencies in the design stage, one can use transfer matrix method of the finite element method and former is rather prefered in ordinary cases. In this study, the finite element method which is utilized for calculation of the propulsion shaft alignment, is introduced to derive the vibration equation of the ship's propulsion shaftings. The digital computer program is developed to solve the above equation, and the details of preparing the input data are described. The method presented in the underlying report was applied to the shafting of ship which has a lignumvitae bearing to verify its reliability and the results of calculation and those of the measurements on rotating shaft show a good agreement. Calculating methods of exciting of forces and damping forces are also discussed for future work.