• 대한기계학회논문집A
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• 제24권9호
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• pp.2371-2380
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• 2000

In this paper, we developed the proximity exposure system with the vertical structure of glass and mask stage to minimize the mask's warp caused by the pull of gravity. This system, which canirradiate the ultra violet through 1440 H 850 $\textrm{mm}^2$ and 1330X 1015 $\textrm{mm}^2$ exposure area, has the followingcharacteristics. The glass stage can be inclined by 80 degrees at vertical structure to load substrate withsafety on it. When the glass stage is the vertical state, the gap control, alignment control and exposureof ultra violet are executed. So, it enhances the pattern uniformity by minimizing the mask's warp. Theglass stage can also control the gap between the mask and the substrate by the coarse and fine motioncontrol. The mask stage can adjust the posture of photomask to the position of substrate by imageprecessing method. The galss stage for the gap control and the mask stage for the alignment aredesigned independently for each function.

• 한국생산제조학회지
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• 제19권4호
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• pp.476-484
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• 2010

Precise positioning stages are often employed for precise machinery. For the purpose of vibration isolation, these precise positioning stages are mounted on a heavy base structure which is supported by compliant springs. Then the base structure is subjected to residual vibration due to the reactive force and vertical moving load induced by the stage motion. This paper investigates the vibration behavior of a positioning stage base and the associated vibration suppression technique. A dynamic model is developed to investigate the base vibration due to the reactive force and moving load effects by the moving stage. An input shaping technique is also developed to suppress the residual vibrations in base structures. Simulations and experiments show that the developed dynamic model adequately represents the base vibration and that the proposed input shaping technique effectively removes the residual vibrations from the positioning stage base.

• 방송공학회논문지
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• 제11권1호
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• pp.138-141
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• 2006

본 논문에서는 다단계 구조의 유리수배 표본화율 변환기의 계산 효율성을 메모리 사용량과 초당 곱셈 수 측면에서 정량적으로 평가한다. 그리고 다단계 구조에서 해상도 보존 조건과 서로소 조건을 설명하고, 각 단계의 최적 변환 비율을 유리수배로 직접 얻을 수 있는 설계 과정을 제시한다. 실제 예로, 44.1KHz 에서 48KHz 로의 표본화율 변환기를 2단계 구조로 구현한 예를 보인다.

• 한국항해항만학회:학술대회논문집
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• 한국항해항만학회 1998년도 추계학술대회논문집:21세기에 대비한 지능형 통합항만관리
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• pp.159-165
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• 1998

In this paper the sway-control problem of a container crane is investigated. The control loop is divided into two stages. The first stage is a modified time optimal control for trolley traversing. The velocity command for trolley traversing consists of three components ; a reference velocity and two feedback signals for compensating the deviations of trolley and sway angle from their desired trajectories. For trolley's exact positioning the trolley dynamics is identified via an error equation identifier structure. The second stage is a nonlinear residual sway control that starts at the end of first stage. The control design for the second stage is investigated from the perspective of controling an underactuated system, and the control law combines the feedback linearization and variable structure control.

• Structural Engineering and Mechanics
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• 제41권1호
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• pp.1-24
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• 2012

A reinforced concrete (RC) framed structure detailed according to non-seismic detailing provisions as per Indian Standard was tested on shake table under dynamic loads. The structure had 3 main storeys and an additional storey to simulate the footing to plinth level. In plan the structure was symmetric with 2 bays in each direction. In order to optimize the information obtained from the tests, tests were planned in three different stages. In the first stage, tests were done with masonry infill panels in one direction to obtain information on the stiffness increase due to addition of infill panels. In second stage, the infills were removed and tests were conducted on the structure without and with tuned liquid dampers (TLD) on the roof of the structure to investigate the effect of TLD on seismic response of the structure. In the third stage, tests were conducted on bare frame structure under biaxial time histories with gradually increasing peak ground acceleration (PGA) till failure. The simulated earthquakes represented low, moderate and severe seismic ground motions. The effects of masonry infill panels on dynamic characteristics of the structure, effectiveness of TLD in reducing the seismic response of structure and the failure patterns of non-seismically detailed structures, are clearly brought out. Details of design and similitude are also discussed.

• International Journal of Naval Architecture and Ocean Engineering
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• 제9권3호
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• pp.315-325
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• 2017

The design dimension may not be satisfactory at the final stage due to the welding during the assembly stage, leading to cutting or adding the components in large structure constructions. The productivity is depend on accuracy of the welding quality especially at assembly stage. Therefore, it is of utmost importance to decide the component dimension during each assembly stage considering the above situations during the designing stage by exactly predicting welding deformation before the welding is done. Further, if the system that predicts whether welding deformation is equipped, it is possible to take measures to reduce deformation through FE analysis, helping in saving time for correcting work by arresting the parts which are prone to having welding deformation. For the FE analysis to predict the deformation of a large steel structure, calculation time, modeling, constraints in each assembly stage and critical welding length have to be considered. In case of fillet welding deformation, around 300 mm is sufficient as a critical welding length of the specimen as proposed by the existing researches. However, the critical length in case of butt welding is around 1000 mm, which is far longer than that suggested in the existing researches. For the external constraint, which occurs as the geometry of structure is changed according to the assembly stage, constraint factor is drawn from the elastic FE analysis and test results, and the magnitude of equivalent force according to constraint is decided. The comparison study for the elastic FE analysis result and measurement for the large steel structure based on the above results reveals that the analysis results are in the range of 80-118% against measurement values, both matching each other well. Further, the deformation of fillet welding in the main plate among the total block occupies 66-89%, making welding deformation in the main plate far larger than the welding deformation in the longitudinal and transverse girders.

• 한국정보통신학회논문지
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• 제23권8호
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• pp.966-974
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• 2019

본 연구에서는 저전력 영역에서의 효율을 개선하기 위해 바이패스 구조를 갖춘 2.4GHz CMOS 전력 증폭기를 제안한다. 바이패스 구조를 설계하기 위해, 구동 증폭단의 공통 게이트 트랜지스터를 두 개로 분할하였다. 공통 게이트 트랜지스터 중 하나는 고출력 전력 모드를 위한 전력단을 구동하도록 설계된다. 다른 공통 게이트 트랜지스터는 저출력 전력 모드를 위해 전력단을 바이 패스하도록 설계하였다. 측정 된 최대 출력은 20.35 dBm이며 효율은 12.10 %이다. 11.52 dBm의 측정 된 출력에서 효율은 전력증폭단을 바이 패스함으로써 1.90 %에서 7.00 %로 향상됨을 확인하였다. 측정 결과를 바탕으로 제안 된 바이 패스 구조의 타당성을 성공적으로 검증 하였다.

• Fisheries and Aquatic Sciences
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• 제6권2호
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• pp.51-58
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• 2003

The gonadal development and the gametogenic cycle and the fine structure of ripe germ cells of the cultured Pacific oyster, Crassostrea gigas were investigated using oysters monthly collected from the southern coast of Korea from October 2000 to September 2001. Monthly changes in the condition index were similar to that of meat weight rate and the highest value was observed in between April and May, and the lowest value in August. The external colors of the testis and the ovary were milky white and yellowish, respectively. The spawning period of the Pacific oyster was continued from May to September, with a peak in July. The gametogenic cycle could be classified into five successive stages: multiplicative stage (December to March), growing stage (March and April), mature stage (April to June), spawning stage (June to August) and resting stage (August to January). Variety of egg yolk granules, lipid granules, mitochondria, and endoplasmic reticula were observed in cytoplasm of ripe oocyte. The spermatozoon consisted of the head, middle piece and tail; including cap-shaped acrosome with domed structure, elliptical shaped nucleus, four mitochondria, two centrioles and flagellum.

• Smart Structures and Systems
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• 제9권3호
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• pp.253-271
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• 2012

Finite element (FE) model updating is a useful tool for global damage detection technique, which identifies the damage of the structure using measured vibration data. This paper presents the application of a finite element model updating method to detect the damage of a small-scale reinforced concrete building structure using measured acceleration data from shaking table tests. An iterative FE model updating strategy using the least-squares solution based on sensitivity of frequency response functions and natural frequencies was provided. In addition, a side constraint to mitigate numerical difficulties associated with ill-conditioning was described. The test structure was subjected to six El Centro 1942 ground motion histories with different Peak Ground Accelerations (PGA) ranging from 0.06 g to 0.5 g, and analytical models corresponding to each stage of the shaking were obtained using the model updating method. Flexural stiffness values of the structural members were chosen as the updating parameters. In model updating at each stage of shaking, the initial values of the parameter were set to those obtained from the previous stage. Severity of damage at each stage of shaking was determined from the change of the updated stiffness values. Results indicated that larger reductions in stiffness values occurred at the slab members than at the wall members, and this was consistent with the observed damage pattern of the test structure.

• 대한수의학회지
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• 제33권1호
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• pp.23-36
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• 1993

To investigate the cycle and relative frequences and the fine structure of seminiferous epithelia in mature Jindo dogs, histologic study was performed. The results obtained were summarized as follows; 1. Type A spermatogonia appeared approximately 1.6 times as many at stage II as compared to stage I while type In spermatogonia appeared small amount in stage III, IV and V. type B spermatogonia were found during the stage VI to VIII, though not detectable during stage I to V. The type B spermatogonia divided at stage VII to produce the preleptotene primary spermatocytes at stage VIII. The number of primary spermatocytes of the leptotene phase markedly increased during stage I to II, and the primary spermatocytes of the pachytene phase were shown the least in number at stage IV. The secondary spermatocytes could be seen only at stage IV. 2. The relative frequencies of each stage from stages I to VIII of the cycle of seminiferous epithelia were 31.6, 11.9, 10.0, 3.2, 8.2, 10.1, 11.7 and 13.2% respectively. 3. On electron microscopic observations, acrosomal vesicle of spermatids appeared larger though the bulk of germ cells were the morphologically same as those of the other animal species. Thread line structures light microscopically observed in the cytoplasm of Sertoli cell were the longitudinal orientation of mitochondria.