• 한국의학물리학회지:의학물리
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• 제17권2호
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• pp.114-122
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• 2006

세기조절방사선치료에는 다엽콜리메타의 구동방식에 따라 static 방법과 dynamic 방법이 있다. 세기조절방사선치료의 정도관리는 치료계획의 정도관리, 치료정보의 전달에 관한 정도관리, 치료전달 과정에 대한 정도관리를 통하여 이루어진다. 여기서는 static 방법과 dynamic 방법에 대하여 같은 조건으로 치료계획 정도관리를 시행하여 dynamic 방법의 환자 적용에 대한 타당성을 살펴보았다. 세기조절방사선치료에서 다엽콜리메타의 움직임이 static 방법인 stop and shoot 방법과 다엽콜리메타의 움직임이 dynamic 방법인 sliding window 방법과 비교검토한 결과 임상표적용적(clinical target volume, CTV)의 크기가 직경 3 cm인 경우에서는 중심점에서의 선량분포 차이가 0.2%였으며, 선량분포의 90% 면적의 차이가 2.7%였으며, CTV의 크기가 직경 7 cm인 경우에서는 중심점에서의 선량분포 차이가 0.2%였으며, 선량분포의 90% 면적의 차이가 2.2%였으며, CTV의 크기가 12 cm인 경우에서는 중심점에서의 선량분포 차이가 0.4%였으며, 선량분포의 90% 면적의 차이가 2.9%였다. 실제 폐암 환자에서도 CTV의 크기에 따라 static 방법과 dynanic 방법에서 중심점에서의 선량 차이는 0.3%에서 0.6%를 나타내고 있다. 가상 펜텀에서는 CTV의 크기에 따라 중심점에서의 측정 선량이나 90% 등선량 곡선 면적이 차이가 없었고, 실제 폐암환자에서는 중심점의 측정선량은 차이가 없었지만 90%등선량곡선의 면적은 CTV 가 커짐에 따라 두 방법간에 차이가 커짐을 알 수 있었다.

• 한국의학물리학회:학술대회논문집
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• 한국의학물리학회 2002년도 Proceedings
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• pp.457-460
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• 2002

The image quality of three-dimensional (3D) images has been widely investigated by the qualitative analysis method. A need remains for an objective and quantitative method to assess the image quality of 3D volume-rendered images. The purpose of this study was to evaluate the quantitative accuracy of distance measurements on 3D volume-rendered images of a dry human skull by using multi-detector computed tomography (MDCT). A radiologist measured five times the twenty-one direct measurement line items composed among twelve reference points on the skull surface with a digital vernier caliper. The water filled skull specimen was scanned with a MDCT according to the section thicknesses of 1.25, 2.50, 3.75, and 5.00 mm for helical (high quality; pitch 3:1) scan mode. MDCT data were reconstructed with its acquisition section thickness and with 1.25 mm section thickness for all scans. An observer also measured seven times the corresponding items on 3D volume-rendered images with measuring tools provided by volumetric analysis software. The quantitative accuracy of distance measurements on the 3D volume-rendered images was statistically evaluated (p-value < 0.05) by comparatively analyzing these measurements with the direct distance measurements. The accuracy of distance measurements on the 3D volume-rendered MDCT images acquired with 1.25, 2.50, 3,75 and 5.00 mm section thickness and reconstructed with its section thickness were 48%, 33%, 23%, and 14%, respectively. Meanwhile, there were insignificant statistical differences in accuracy of distance measurements among 3D volume-rendered images reconstructed with 1.25 mm section thickness for the each acquisition section thickness. MDCT images acquired with thick section thickness and reconstructed with thin section thickness in helical scan mode should be effectively used in medical planning of 3D volume-rendered images. The quantitative analysis of distance measurement may be a useful tool for evaluating the quantitative accuracy and the defining optimal parameters of 3D volume-rendered CT images.

• 한국대기환경학회:학술대회논문집
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• 한국대기환경학회 2002년도 추계학술대회 논문집
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• pp.358-359
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• 2002

Particulate matter smaller than $10{\mu}textrm{m}$ in aerodynamic diameter (PM10) is known as thoracic particles that are capable of reaching the thoracic region of humans. PM10 is further divided into two size ranges, which are fine particles (nuclei mode plus accumulation mode) and coarse particles, based on different sources and chemical composition. Fine particles can penetrate deep into the alveolar region of the human lungs, while coarse particles be deposited in the upper respiratory system. (omitted)

• 대한전기학회논문지
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• 제41권7호
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• pp.823-828
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• 1992

A thermionic energy converter test station is constructed for the study of electromagnetic energy generation. Of particular interest is the frequency variations due to changes in the interelectrode gap, the electrode temperature, and the cesium vapor pressure. It is found experimentally that the most intense ratio-frequency(rf) oscillations occur at two non-overlapping regions.

• Journal of electromagnetic engineering and science
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• 제3권2호
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• pp.140-146
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• 2003

In this paper, the design of a channel filter and its group-delay-and-amplitude equalizer is carried out for the Ka-band satellite transponder subsystem. The 8th order dual-mode filter is employed for high selectivity around the band-edges with an elliptic-integral function response and has an in-line configuration. The 2-pole, reflection-type, group-delay equalizer is designed and manufactured to reduce the group-delay and amplitude variation, which can be large for such a high order filter. It is noted that in both the filter and equalizer, adopting the dual-mode coupling mechanism leads to less mass and volume. Through measurement, the performance of the realized group-delay-equalized filter is shown to meet the equipment requirements and to be appropriate for the satellite input multiplexer.

• 한국전산구조공학회:학술대회논문집
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• 한국전산구조공학회 2005년도 춘계 학술발표회 논문집
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• pp.335-342
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• 2005

Using higher order Mindlin plates and piezoelectric materials, eigenvalue problems are considered. Since piezoelectric crystal resonators produce a proper amount of electric signal for a thickness-shear frequency, the objective is to decouple the thickness-shear mode from the others. Design variables are the bulk material densities corresponding to the mass of masking plates for electrodes. The design sensitivity expressions for the thickness-shear frequency and mode shape vector are derived using direct differentiation method(DDM). Using the developed design sensitivity analysis (DSA) method, we formulate a topology optimization problem whose objective function is to maximize the thickness-shear component of strain energy density at the thickness-shear mode. Constraints are the allowable volume and area of masking plate. Numerical examples show that the optimal design yields an improved mode shape and thickness-shear energy.

• Asian Journal for Public Opinion Research
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• 제1권2호
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• pp.147-150
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• 2014

Mixed-mode (or multi-mode) surveys and (volunteer) web panels were recently introduced as ways to cope with changes in the social survey environment, which is going through a rapid and massive transformation. The direction, speed, and magnitude of these changes have been clear in Korea, too. Enumerated in Figure 1 are the social surveys between 1960 and 2010 archived by the Korean Social Science Data Archive (KOSSDA) 2. The left panel shows the exponential growth in the overall volume. The other two panels, more importantly, show the changes in the composition. Mixed-mode and online surveys are rapidly increasing their shares and are fast becoming de facto standards in Korea, as in many other countries.

• Journal of the Optical Society of Korea
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• 제2권2호
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• pp.58-63
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• 1998

Cross-talk effects in high-density volume holographic interconnections are investigated using perturbative iteration method of the integral form of Maxwell's wave equation. In this method, the paraxial approximation and negligence of backward scattering introduced in conventional coupled mode theory is not assumed. Interaction geometries consisting of non-coplanar light waves and multiple index gratings are studied. Arbitrary light polarization is considered. Systematic analysis of cross-talk effects due to multiple index gratings is performed in increasing level of diffraction orders corresponding to successive iterations. Some numerical examples are given for first and third order diffraction.

• Journal of the Optical Society of Korea
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• 제2권1호
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• pp.38-41
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• 1998

The method of using fiber speckle patterns can be applied to the multiplexing of volume holograms. Fiber speckle patterns enable various multiplexing techniques such as shift, angular, and mode-scrambling methods Hybrid methods involving more than one multiplexing technique are also possible. Some images are stored and retrieved with one or two of multiplexing methods, and the experimental results are discussed.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2010년도 춘계학술대회 논문집
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• pp.2297-2302
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• 2010

The status and effectiveness of Bi-modal Tram is analyzed through the comparison of the transport effectiveness and operation cost between the public transportation systems (bus, light rail transit) considering the vehicle and operation characteristic of new transit system Bi-modal Tram. The standard operation schedule is established in consideration of the vehicle specification and operation characteristic of main public transportation modes, and then the annual average operation cost is estimated depending on the volume, speed, analysis length for respective public transportation mode. Through analyzing the operation cost and distribution characteristic of public transportation modes depending on the transport volume and travel speed, the operational efficiency suitable for the city is derived. It is concluded that the operational efficiency of Bi-modal Tram is superior to that of the bus and light rail transit on the aspect of travel volume and operation speed.