• 한국측량학회지
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• 제8권2호
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• pp.23-29
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• 1990

측정용 사진기는 정교한 소형 구조물의 해석시 최소 촬영거리에 따른 초근접 촬영에 어려움이 있으므로 초점거리 조절이 자유로와 초근접 촬영이 가능한 비측정용 사진기를 이용하는 것이 바람직하다. 또한 많은 시간과 노력을 요하는 기준점측량의 난제가 해결된다면 보다 신속한 초근접 사진해석이 가능할 것이다. 본 연구는 정오차 보정이 이루어진 비측정용 사진기로 소형 피사체를 초근접 촬영하고 번들조정기법에 의해 해석한 후, 오차의 특성을 다양하게 분석하므로써 비측정용 사진기의 효용성을 제시하고, 자체 기준점측량 기법을 도입, 기준점측량의 문제를 효율적으로 해결하기 위한 것이다. 연구결과 비측정용 사진기에 의한 초근접 사진해석의 우월성과 자체 기준점측량기법의 적용가능성이 입증되었으므로 소형구조물을 비롯한 첨단부품의 정밀해석에 그 응용이 가능할 것으로 기대된다.

• 대한기계학회논문집A
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• 제29권1호
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• pp.67-73
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• 2005

The paper presents a single-heater microfluid injector, whose ejected droplet volume is adjusted by digital current path control for a single microheater. The previous droplet volume adjustable methods have used the digital current control for multiple heaters or the analog current control for a single heater, while the present method uses the digital current control for a single microheater. Two different microinjectors, having a rectangular heater and a circular hearter, are designed and fabricated in the chip area of $7.64\;mm{\times}5.26\;mm$. The fabricated microinjectors have been tested and characterized for the number, size, shape and lifetime of the generated bubbles as well as for the volume and velocity of the ejected droplets. The input power for the rectangular heater and the circular heater has been varied in the ranges of $8.7{\sim}24.9{\mu}W\;and\;8.1{\sim}43.8{\mu}W$, respectively. The projected area of the generated bubble has been changed in the ranges of $440{\sim}l,3600{\mu}m^2\;and\;800{\sim}3,300{\mu}m^2$ for the rectangular heater and the circular heater, respectively. The microinjector with the rectangular heater ejects three discrete levels of the droplet in the volume range of $9.4{\sim}20.7pl$ with the velocity range of $0.8{\sim}1.7m/s$, while the microinjector with the circular heater achieves five discrete levels of the droplet in the volume range of $7.4{\sim}27.4pl$ with the velocity range of $0.5{\sim}2.8m/s$.

• Journal of Advanced Marine Engineering and Technology
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• 제25권5호
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• pp.1086-1090
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• 2001

In this paper, a method deciding the permissible gains of the P and PT controllers for a retarded process under stable condition is proposed. For analysis, the controlled process is assumed to be first-order system with time delay. At first, the adjustable parameter sets causing stability limit are obtained based on the frequency domain condition which makes the roots of the characteristic equation locate on the imaginary axis. And the cut-in frequency ${\omega}_p$ to bring the parameter set to P control from PI control is derived is derived in terms of L and $T_m$ then ${\omega}_p$ is used to compute the maximum gain with stable condition. The results indicate that the permissible controller gains can be described by a unique if parameters L and $T_m$ are know.

• Journal of electromagnetic engineering and science
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• 제8권2호
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• pp.64-69
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• 2008

In this paper, we have proposed the pattern adjustable base station antenna for WCDMA applications. The proposed antenna consists of an omni-antenna(sleeve monopole) and two movable reflectors. The two reflectors can be controlled by mechanically and used to adjust the horizontal pattern of the base station antenna. The antenna was designed, fabricated, and measured. The antenna covers the entire WCDMA band for VSWR<1.4. The measured antenna gain is more than 15 dBi over the operating frequency range. By changing the angle (a) and the distance (d) of the antenna, the pattern adjustment of the proposed base station antenna is found to be possible.

• 가정과삶의질연구
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• 제19권4호
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• pp.85-103
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• 2001

After-school activities were examined for 449 rural children in first through seventh grades. Childrens engagement of after-school activities were significantly different by child and family characteristics, especially childrens age and behavior control ability. Findings showed a decline in amount of time spent studying and reading and a raise in going to a game-room. Childrens school achievement, emotional and social development were also differed by a range of after-school activities. Children spent more time in studying and reading showed higher grades, happiness, school life. Teachers reported greater aggressive behavior and less adjustment of school life among children participating more in game related activities and hanging out. Watching TV, doing house chores and visiting friends were not variables which showed different outcomes.

• 한국수소및신에너지학회논문집
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• 제25권3호
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• pp.240-246
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• 2014

In order to develop a universal cryogenic piston pump of small size for increasing utilization of liquid hydrogen, dynamic compression performance of piston pump were evaluated and improvements were also discussed for piston rod and piston tip. The cryogenic piston pump has crosshead structure and inclined cup shape piston tip. As the results, it was found that i) insulation of heat flow from piston-rod part is required for stable operation ii) improving the self-clearance adjustment effect of piston tip and reducing piston eccentricity were desirable to promote pumping pressure and operating range.

• Journal of Advanced Marine Engineering and Technology
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• 제29권7호
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• pp.744-749
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• 2005

This paper describes the performance improvement of power control system of magnetron (MGT) for microwave oven. The MGT is used extensively in household microwave oven and industrial microwave heating devices, and is operated by 3.0[kV] $\∼$5.0[kV] dc high voltage. The proposed power supply is consisted of a bridge rectifier, step-up converter(SUC) and its controller, half bridge inverter(HBI) and its controller, and full wave double voltage rectifier(DVR). In the proposed system, a good power factor can be obtained by the SUC' switching method that the inductor current waveforms follows that of the rectified voltage, and a line input power can be controlled to a range of 17.5[$\%$] by duty ratio (DR) adjustment of the HBI.

• Nutritional Sciences
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• 제7권1호
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• pp.53-58
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• 2004

The Multiethnic Cohort Study was designed to study prospectively the relationship of diet and other lifestyle factors to the risk of cancer. The cohort was established in 1993-1996 in Hawaii and California (primarily Los Angeles) and included a representative sample of more than 215,000 men and women primarily from five different ethnic groups: Japanese, whites, Native Hawaiians, Latinos, and African- Americans. Because of the emphasis on diet, great attention was paid to developing and pre-testing a self-administered quantitative food frequency questionnaire that would adequately assess food and nutrient intakes in these groups. An extensive food composition database was also created for the study. In addition, during data collection, a calibration study was conducted that makes possible adjustment for measurement error in nutrient intakes and valid comparison of intakes across the several ethnic groups. At the present time, blood and urine specimens are being collected from cohort participants and should yield a biorepository of more than 80,000 subjects. Baseline data indicate that the cohort is well representative of the general population of Hawaii and California, so that results can be generalized. These data also show a wide range in dietary intakes and in other lifestyle variables that should facilitate the testing of etiologic hypotheses.

• Communications for Statistical Applications and Methods
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• 제12권1호
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• pp.29-38
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• 2005

In sample design, determining the weights of estimates becomes usually great influence on the result. In this article, raking methods are applied to different domain and depending on the range of the domain and sample size, the results of estimates are explained and compared. For the comparison, we use the MSE, MAE, MSPE and MAPE with Actual State of Minor Enterprisers Human Resources Survey data in 2001. The simulation result shows that more elaborate method is superior to the widely used method as expected but the difference is not quite significant.

• 제어로봇시스템학회논문지
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• 제15권10호
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• pp.1021-1028
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• 2009

In this paper, a location identification for a cleaning robot using a camera shooting forward a room ceiling which kas three point landmarks is introduced. These three points are made from a laser source which is placed on an auto charger. A fisheye lens covering almost 150 degrees is utilized and the image is transformed to a camera image grabber. The widly shot image has an inevitable distortion even if wide range is coverd. This distortion is flatten using an image warping scheme. Several vision processing techniques such as an intersection extraction erosion, and curve fitting are employed. Next, three point marks are identified and their correspondence is investigated. Through this image processing and image distortion adjustment, a robot location in a wide geometrical coverage is identified.