• 한국방사선학회논문지
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• 제3권1호
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• pp.5-9
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• 2009

디지털 방사선 검출기의 주된 연구동향은 영상의 해상도 향상, 대면적화, 동영상 구현 등${\cdots}$ 이라 할 수 있다. 이런 연구는 방사선 변환과정에 따라 크게 직접변환 방식과 간접 변환 방식으로 나눌 수 있으며 각각 고유한 장단점을 내포하고 있다. 간접변환 방식의 경우 형광체의 사용으로 인한 Light scattering 문제로 해상력의 저하 그리고 직접방식의 경우는 낮은 system 안정성과 동영상 구현의 어려움 등이 대표적이라 할 수 있다. 이런 문제를 해결하기 위한 연구로써 액정을 이용한 엑스선 검출기 연구가 진행되었으나 그 구조의 특성상 균일한 액정의 주입이 어려워 제작에 있어 많은 어려움이 있다. 따라서 본 논문에서는 기존의 문제점을 해결할 수 있는 구조를 제안하고 이를 Simulation 통해 제안된 구조의 가능성을 검토해 보았다.

• 한국콘텐츠학회논문지
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• 제10권7호
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• pp.253-258
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• 2010

임상에서 사용되고 있는 영상증강장치는 사용하는데 따라 경시적으로 변화되어 휘도가 열화되고 성능이 저하되어, 동일한 진단력을 유지하기 위해서 X선 출력을 증가시키게 되어 환자선량이 증가되는 원인이 된다. 하지만 정확한 연구가 많지 않아 국내에 사용 중인 장치를 대상으로 사용에 따른 변환계수와 해상력을 측정해 보았으며, 그 결과 1년 미만의 장치에 대해 사용년한이 6년 미만 되는 장비의 경우 변환계수가 25% 감소되었고, 해상력은 3.4 lp/mm에서 2.5 lp/mm로 감소되어 사용이 증가할수록 환자선량의 증가와 더불어 정확한 검사가 어려워 적절한 관리가 필요한 것으로 나타났다.

• 한국습지학회지
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• 제3권1호
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• pp.39-48
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• 2001

연안습지의 손실은 국내 연안을 둘러싼 이해상충의 주요 요인이다. 본 연구에서는 이해상충과 관련된 국내 연안관리 및 습지손실과 관련된 상황, 이해상충의 배경 및 특성, 한국의 대규모 습지 훼손사례로 볼 수 있는 시화호, 순천만, 금강하구, 강원도 석호지역에 대한 이해상충의 실태와 조정사례를 근거로 이해상충해결을 위한 조정방법과 절차를 정리하였다.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2000년도 추계종합학술대회 논문집(2)
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• pp.164-167
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• 2000

This paper introduces the design of high-speed analog-to-digital converter for hard disk drive (HDD) read channel. This is based on autozero technique for low-error rate, and Double Speed Dual ADC(DSDA) technique lot efficiently increasing the conversion speed of A/D converter. This An is designed by 6bit resolution, 800M sample/s maximum conversion rate, 390㎽ power dissipation, one clock cycle latency in 0.65 $\mu\textrm{m}$ CMOS technology.

• ETRI Journal
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• 제29권4호
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• pp.542-544
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• 2007

In this study, several methods to convert rain rate data for various time intervals to one-minute rates are compared. High-resolution tipping bucket precipitation records for seven locations in a tropical region are analyzed and compared using these conversion models. The Segal, Chebil, and Burgueno methods give the smallest average errors below 10% at different integration times.

• 한국환경과학회:학술대회논문집
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• 한국환경과학회 2003년도 International Symposium on Clean Environment
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• pp.226-231
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• 2003

A coupling system of MM5 and POM using Stampi with different kinds of parallel computer is proposed and comparative numerical simulations of mesoscale wind induced by topography around East Sea/Sea of Japan are carried out. The results are as follows： 1) Strong horizontal conversion is induced by high mountain Pekdoo at its leeside. 2) The conversion winds at lee of high mountain are not clear in monthly and yearly mean NCEP-reanalysis because of coarse resolution of 1.86 degree by 1.86 degree. But Wind conversion is well simulated at atmosphere and ocean coupling system. And the conversion area of lee side of mountain is also agreed well with observed data of NSCAT launched in satellite ADEOS. 3) The surface ocean current is well correspondent with wind direction, induced by high mountains. And small different wind field information lead the different of particle distribution in numerical experiments of particle distribution on ocean surface.

• Bulletin of the Korean Chemical Society
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• 제8권1호
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• pp.45-47
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• 1987

After conversion to their 3,5-dinitrobenzoyl or 3,5-dinitroanilide derivatives, the enantiomers of a number of drugs may be chromatographically separated on various ${\alpha}$-arylalkylamine-derived chiral stationary phases (CSPs). While each CSP used in this study is useful, CSP 1 is best able to resolve the 3,5-dinitroanilide derivative of Ibuprofen while CSP 9 generally gives rather large ${\alpha}$ values for the resolution of 3,5-dinitrobenzoyl derivatives of the enantiomers of ${\beta}$-adrenergic blocking drugs.

• The Journal of the Acoustical Society of Korea
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• 제15권1E호
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• pp.70-76
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• 1996

We proposed to use shear waves instead of longitudinal waves in a STAM (scanning tomographic acoustic microscope system) in which the specimens are solid. For any specimen with a shear modulus, mode conversion will take place at the water-solid interface. Some of the energy of the insonifying longitudinal waves in the water will convert to shear wave energy within the specimen. The shear wave energy is detectable and can be used for tomographic reconstruction. The resolution limitation of STAM depends on the available angular view and the acoustic wavelength. While wave transmission in most solid specimens is limited to about 20°for longitudinal waves, we show that it is about twice that high for shear waves. Since the wavelength of the shear wave is shorter than that of the longitudinal wave, we are able to achieve the high resolution. In order to compare the operation of a shear-wave STAM with that of the conventional longitudinal-wave STAM we have simulated tomographic reconstruction for each. Our simulation results with aluminum specimen and back-and-forth propagation algorithm showed resolution of a shear-wave STAM is better than that of a longitudinal-wave STAM.

• Journal of Korean Society for Atmospheric Environment
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• 제18권E2호
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• pp.107-120
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• 2002

Dimethyl sulfide (DMS) is the major sulfur gas released from the ocean. The atmospheric DMS released from the ocean is oxidized mainly by hydroxyl (OH) radical during the day and nitrate (NO$_3$) radical at night to form sulfur dioxide (SO$_2$) as well as other stable products. The oxidation mechanism of DMS via OH has been known to proceed by two channels; abstraction and addition channels. The major intermediate product of the addition channel has been known to be dimethylsulfoxide (DMSO) based on laboratory chamber studies and field experiments. However, a branching ratio for DMSO formation is still uncertain. The reaction of DMSO with OH ultimately produces SO$_2$and dimethylsulfone. The major product of the abstraction channel has known to be SO$_2$from laboratory chamber studies. But overall conversion efficiency for DMS to SO$_2$from DMS oxidation is still inconsistent in the literature. Based on laboratory and field studies, the conversion efficiency from the abstraction channel is likely to be greater than 0.5, while that from the addition channel is likely to be greater than 0.6. Overall conversion efficiency from DMS to SO$_2$might be greater than 0.5 based on the above two values in the remote marine boundary layer (MBL). This high efficiency in the remote MBL is supported by strong coupling between DMS and SO$_2$measurements with high temporal resolution.

• 센서학회지
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• 제24권6호
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• pp.359-363
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• 2015

This paper proposes an algorithm that reduces the conversion time of a single-slope A/D converter (SSADC) that has n-bit resolution, which typically is limited by conversion time taking up to $2^n$ clock cycles for an operation. To improve this situation, we have researched a novel hybrid-type A/D converter that consists of a pseudo-pipeline A/D converter and a conventional SSADC. The pseudo-pipeline A/D converter, using a single-stage of analog components, determines the most significant bits (MSBs) or upper bits and the conventional SSADC determines the remaining bits. Therefore, the modified SSADC, similar to the hybrid-type A/D converter, is able to significantly reduce the conversion time because the pseudo-pipeline A/D converter, which determines the MSBs (or upper bits), does not rely on a clock. The proposed A/D converter was designed using a $0.35-{\mu}m$ 2-poly 4-metal standard complementary metal oxide semiconductor (CMOS) technology process; additionally, its characteristics were simulated.