• 에너지공학
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• 제22권2호
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• pp.156-168
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• 2013

이 연구에서는 2007년, 2010년에 수행한 울릉분지 1, 2차 시추 지역의 시추공(UBGH1-1, UBGH1-4, UBGH1-9, UBGH1-10, UBGH1-14, UBGH2-2-1, UBGH2-2-2, UBGH2-6, UBGH2-9, UBGH2-10, UBGH2-11)에서 취득한 물리검층 및 코어분석 자료로 추정한 가스하이드레이트 함유층 주요 물성 자료를 활용하여 불균질성을 반영할 격자 수준의 3차원 공간 분포 모델링을 수행하였다. 가스하이드레이트 함유층 내 퇴적상의 공간 분포 추정을 위하여 퇴적상 추정 자료를 각 시추공별로 3차원 격자셀에 입력하고 순차지표시뮬레이션으로 3차원 분포를 모델링하였다. 가스하이드레이트 함유층의 공극률과 가스하이드레이트포화율은 퇴적상 분포 모델을 기반으로 순차가우스시뮬레이션을 통해 3차원 공간 물성 분포를 추정하였다.

• 한국수자원학회논문집
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• 제32권5호
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• pp.515-524
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• 1999

본 연구는 토양수분의 공간적 분포를 고려하는 과정에서 TOPMODEL이 가지고 있는 구조상의 문제를 해결하는 방안을 제시한다. 포화초과유출을 모의하는 기존 TOPMODEL은 유출모의시 유역내 포화부분의 공간적인 정보를 반영하는 과정에 있어 포화면적의 연결성을 고려한 유출 알고리즘의 개발로 발전되었다. 개발된 알고리즘은 TOPMODEL의 매개변수를 증기시키지 않고 개선된 유출경로 추적의 근거를 제시함으로써 모형의 합리성과 적용성을 제고시켰다. 본 연구에서 개발된 포화면적 연결모형과 기본적인 통계적 입력모형형태의 TOPMODEL을 국제수문개발계획 대상유역인 위천유역내의 동곡소유역에 적용한 결과 본 연구에서 개발된 포화면적 연결모형이 다른 두 모형에서 발생하는 모의시 과도첨두유량계산의 문제를 해결할 수 있었다.

• 대한의용생체공학회:의공학회지
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• 제44권6호
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• pp.450-464
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• 2023

Pulse oximetry, a non-invasive technique for evaluating blood oxygen saturation, conventionally depends on isolated measurements, rendering it vulnerable to factors like illumination profile, spatial blood flow fluctuations, and skin pigmentation. Previous efforts to address these issues through imaging systems often employed red and near-infrared illuminations with distinct profiles, leading to inconsistent ratios of transmitted light and the potential for errors in calculating spatial oxygen saturation distributions. While an integrating sphere was recently utilized as an illumination source to achieve uniform red and near-infrared illumination profiles on the sample surface, its bulkiness presented practical challenges. In this work, we have enhanced the pulse oximetry imaging system by transitioning illumination from an integrating sphere to a multi-wavelength LED configuration. This adjustment ensures simultaneous emission of red and near-infrared light from the same position, creating a homogeneous illumination profile on the sample surface. This approach guarantees consistent patterns of red and near-infrared illuminations that are spatially uniform. The sustained ratio between transmitted red and near-infrared light across space enables precise calculation of the spatial distribution of oxygen saturation, making our pulse oximetry imaging system more compact and portable without compromising accuracy. Our work significantly contributes to obtaining spatial information on blood oxygen saturation, providing valuable insights into tissue oxygenation in peripheral regions.

• 한국지하수토양환경학회:학술대회논문집
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• 한국지하수토양환경학회 2004년도 임시총회 및 추계학술발표회
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• pp.29-32
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• 2004

Gaseous partitioning tracer test has been used for determining the volume and spatial distribution of residual non-aqueous phase liquid (NAPL) in the unsaturated soils. In this study, an experimental method for measuring the content of gas-exposed NAPL as well as that of total NAPL in a sand during air sparging was developed. Two different gaseous phase NAPL-partitioning tracers were used; n-pentane, with very low water solubility, was used as the tracer that partitions into NAPL that is only in contact with the mobile gas, and chloroform, with fairly good water solubility, was selected for detecting total NAPL content in the sand. Helium and difluromethanewere used as the non- reactive tracer and water-partitioning tracers, respectively. Using n-decane as a model NAPL (NAPL saturation of 0.018), 25.6% of total NAPL was detected by n-pentane at the water saturation of 0.68. Oniy 9.1% of total NAPL was detected by n-pentane at the water saturation of 0.84. This result implies that the quantity of gas-exposed NAPL increased about three times when the water saturation decreased from 0.84 to 0.68. At the water saturation of 0.68, more than 90% of total NAPL was detected by chloroform while 65.8% of total NAPL was detected by chloroform at the water saturation of 0.84. Considering that the removal rate of NAPL during air sparging for NAPL-contaminated aquifer is expected to be greatly dependent upon the spatial arrangement of NAPL phase with respect to the mobile gas, this new approach may provide useful information for investigating the mass transfer process during air-driven remedial processes fer NAPL-contaminated subsurface environment.

• 한국정보통신학회:학술대회논문집
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• 한국정보통신학회 2017년도 추계학술대회
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• pp.705-707
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• 2017

스테레오기반의 공간방사선 탐지장치는 방사선원에 대한 공간분포정보 뿐만 아니라 탐지장치로부터 선원까지의 거리정보를 얻을 수 있어 기존 방사선 영상화 장치보다 선원에 대한 효율적인 정보를 제공한다. 또한 감마선원의 스펙트럼 및 종류에 대한 정보를 고속으로 제공하기 위해서는 감도가 높은 고감도 검출센서가 필요하며 고선량에서의 포화되는 현상을 해소할 수 있는 기법이 필요하다. 본 논문에서는 다종 감마선 공간분포 측정을 위해 고감도 센서를 구성하고, 검출모듈의 기능을 개선하여 고선량에서의 포화상태를 해소함으로써 단일센서로 탐지범위 증대를 위한 연구를 수행하였다. 본 논문의 결과는 향후 스테레오기반의 감마선 탐지장치의 성능개선을 위해 활용될 것이다.

• 한국진공학회지
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• 제8권3B호
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• pp.368-375
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• 1999

The Maxwell equation and the transformer equivalent-circuit model are applied to a radio frequency planar inductively coupled plasma. The spatial distribution of the vector potential, the magnetic field, and the electric field are obtained analytically. As a result, the plasma current, the mutual inductance between the coil and the plasma, and the self inductance of plasma are found to increase with increasing skin depth. The spatial distribution of absorbed power has maximum where the antenna coil exists, and has a similar profile to that of the induced electric field. The power transfer efficiency is found to increase with increasing gas pressure before a saturation around p+ 20mTorr, while it shows an increase with the plasma density before a slight decrease around a density of $5\times10^{11}/\textrm{cm}^3$.

• Journal of Magnetics
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• 제15권4호
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• pp.190-193
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• 2010

The design of joints in a transformer core significantly affects the transformer's efficiency. Air gaps cause variations in the flux distribution at the joints of the laminations, which depend on the geometry. Two similar samples consisting of electrical steel strips and amorphous ribbons were made. The spatial flux distributions were determined using an array of search coils for each sample. 2D models of these samples were created and examined by finite element analysis. The magnetic flux distribution for each lamination in the samples was computed. The results show that the flux density in amorphous ribbons above and below the air gap starts to approach saturation at lower flux density levels than for electrical steel. The flux density measured using the search coil under the air gap is increased in amorphous ribbons and decreased in the electrical steel with increasing frequency.

• 한국초전도ㆍ저온공학회논문지
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• 제3권2호
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• pp.77-83
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• 2001

The thermal characteristics of solid nitrogen are investigated by experiment and analysis for the purpose of evaluating its feasibility as a cooling medium for HTS (high T$_{c}$ superconductor) magnets. A cryostat to refrigerate a liquid-nitrogen container well below its freezing temperature with a 2-stage GM cryocooler is designed and constructed. The spatial distribution of temperature is measure as a function of time during the freezing and melting processes. from which the thermal diffusivity of solid nitrogen can be approximately calculated. the freezing process is formulated and solved by the integral method with an assumption of phase equilibrium at the solid-liquid interface and experimental observation. It may be concluded that the thermal diffusion in solid phase is much slower than in liquid and the degree of super-saturation is quite severe in the solidification of nitrogen.n.

• 대한토목학회논문집
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• 제32권5B호
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• pp.287-293
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• 2012

본 연구의 목적은 지형지수를 기반으로 유역의 포화도 및 그에 따른 유출역의 변화를 도시할 수 있는 방법론을 제시해 보고자 하는 것이다. 지형지수의 산정에는 ${\infty}$-흐름방향방법을 적용하여 8-흐름방향방법이 갖는 고정된 흐름방향에 대한 구속에서 벗어남과 동시에 최소한의 흐름분산 모의를 가능하게 하였다. 산정된 지형지수의 도수분포도를 작성해 본 결과 동일한 유역에 대하여 수행된 기존의 연구 성과와 유사하게 나타나 본 연구에서 제안한 방법론에 대한 신뢰성을 확인할 수 있었다. 여누가확률밀도함수의 형태로 정의되는 포화도의 개념에 따라 포화토층의 공간적 분포를 도시해 본 결과 유역의 가변성 유출역에 대한 명시적인 접근을 가능하게 하여 강우-유출현상의 동적특성이나 비선형성에 대한 합리적인 분석 수단을 제공할 수 있을 것으로 판단된다.

• 센서학회지
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• 제27권6호
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• pp.386-391
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• 2018

To analyze the film cooling in a liquid rocket engine, it is necessary to understand the characteristics of the wall-impingement liquid film. We designed an optimal two-dimensional device for measuring the thickness of the liquid film thickness. This device quantitatively measures the liquid-film thickness distribution. In previous liquid-film thickness measuring devices, the liquid film was formed over the entire area of the sensor. However, its formation depended on injection conditions. To compensate for this, optimal resistors are selected. Additionally, saturation variations with partial saturation are analyzed. Furthermore, calibration using the enhanced plate method is conducted with improvements in spatial resolution. The device designed here can be used to analyze the properties of an impingement liquid film with a slit injector. This study can be used for film-cooling analysis in liquid rocket engines.