• 센서학회지
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• 제17권5호
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• pp.329-337
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• 2008

Simple, small and portable oxygen sensors were fabricated by tape casting technique. Yttria stabilized zirconia containing cordierite ceramics (YSZC) were used as a porous diffused layer of oxygen in pumping cell. Yttria stabilized zirconia (YSZ) solid electrolyte, YSZC porous diffusion layer and heater-patterned ceramic sheets were prepared by co- firing method. Limit current characteristics and the linear relationship of current to oxygen concentration were observed. Viscosity variation of the slurries both YSZ and YSZC showed a similar behavior, but micro pores in the fired sheet were increased with increasing of the cordierite amount. Molecular diffusion was dominated due to the formation of large pores in porous diffusion layer. The plateau range of limit current in porous-type oxygen sensor was narrow than the one of aperture-type oxygen sensor. However limit current curve was appeared in porous-type oxygen sensor even at the lower applied voltage. The plateau range of limit-current was widen as increasing the thickness of porous diffusion layer of the YSZ containing cordierite. Measuring temperature of $600{\sim}650^{\circ}C$ was recommended for limit-current oxygen sensor. Porous diffusion layer-type oxygen sensor showed faster response than the aperture-type one and was stable up to 30 days running without any crack at interface between the layers.

• 지질공학
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• 제1권1호
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• pp.137-145
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• 1991

열극암반에서의 유동특성은 석유산업, 지열수탐사, 지하수의 오염문제, 지하 동굴건설 등 많은 공학적 분야에서 선결되어야 하는 중요성을 갖고 있다. 암반을 통한 지하수의 유동은 연속체 개념과 불연속열극 개념에 의하여 수치모형화 되고 또한 해석되고 있다. 불연속 열극체계 개념은 국지적인 각 열극의 특성을 강조하는 반면, 다공성매질 개념은 수리학적 파라메타의 평균값을 쓰기 때문에 각 열극의 특성은 무시하게 된다. 지하동굴에서 관찰된 지하수 유입특성에 의하면, 지하수는 channel 형태로 유동한다고 해석되어지고 있다. 이러한 channel 현상은 복합적인 열극의 기하학적 특성에 따른 열극틈의 변화에 의하여 이루어 진다.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2005년도 추계학술대회 논문집
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• pp.576-580
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• 2005

New real-time confocal microscopy using spectral encoding technique and slit confocal aperture is proposed and designed. Spectral encoding technique, which encodes one-dimensional spatial information of a specimen in wavelength, and slit aperture make it possible to obtain two-dimensional lateral image of the specimen simultaneously at standard video rates without expensive scanning units such as polygon mirrors and galvano mirrors. The working principle and the configuration of the system are explained. The variation in axial responses for the simplified model of the system with normalized slit width is numerically analyzed based on the wave optics theory. Slit width that directly affects the depth discrimination of the system is determined by a compromise between axial resolution and signal intensity from the simulation result. On the assumption of the lateral sampling resolution of 50 nm, design variables and governing equations of the system are derived. The system is designed to have the mapping error less than the half pixel size, to be diffraction-limited and to have the maximum illumination efficiency. The designed system has the FOV of $12.8um{\times}9.6um$, the theoretical axial FWHM of 1.1 um and the lateral magnification of-367.8.

• 대한원격탐사학회지
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• 제37권4호
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• pp.789-802
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• 2021

Synthetic Aperture Radar (SAR) at C-band is an ideal remote sensing system for crop monitoring owing to its short wavelength, which interacts with the upper parts of the crop canopy. This study evaluated the potential of dual polarimetric Sentinel-1 at C-band for monitoring rice phenology. Rice phenological variations occur in a short period. Hence, the short revisit time of Sentinel-1 SAR system can facilitate the tracking of short-term temporal morphological variations in rice crop growth. The sensitivity of SAR backscattering coefficients, backscattering ratio, and polarimetric decomposition parameters on rice phenological stages were investigated through a time-series analysis of 33 Sentinel-1 Single Look Complex images collected from 10th April to 25th October 2020 in Gimhae, South Korea. Based on the observed temporal variations in SAR parameters, we could identify and distinguish the phenological stages of the Gimhae rice growth cycle. The backscattering coefficient in VH polarisation and polarimetric decomposition parameters showed high sensitivity to rice growth. However, amongst SAR parameters estimated in this study, the VH backscattering coefficient realistically identifies all phenological stages, and its temporal variation patterns are preserved in both Sentinel-1A (S1A) and Sentinel-1B (S1B). Polarimetric decomposition parameters exhibited some offsets in successive acquisitions from S1A and S1B. Further studies with data collected from various incidence angles are crucial to determine the impact of different incidence angles on polarimetric decomposition parameters in rice paddy fields.

• 대한원격탐사학회지
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• 제31권2호
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• pp.101-110
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• 2015

레이더 간섭도는 대기오차, 위성 궤도 오차, 처리 오차 등 다양한 오차를 포함하고 있다. 특히 이온층에 의한 위상 지연오차는 파장과 비례 관계에 있기 때문에 장파장을 사용하는 레이더 영상의 경우 이에 대한 오차 보정이 필수적으로 요구된다. 그에 관한 연구로 최근 멀티간섭기법(Multiple Aperture SAR Interferometry, MAI)에 기반된 레이더 간섭도 위상 오차 보정 기법이 개발되었다. 본 연구에서는 이 기법에 대한 소개와 간섭도 생성이 불가능한 지역에 대해서 방향 필터를 이용한 활용 방법을 제시했다. 또한 제시된 방법을 서해 연안 지역을 포함하는 ALOS PALSAR 간섭쌍에 대해 적용하였다. 우선, 기법 비교를 위해 일반적으로 궤도 오차 보정에 많이 사용되는 2차원 다항식 보정 기법을 이용하여 레이더 간섭도의 위상 오차 보정을 수행했다. 그 결과 비행방향을 따라 초기 레이더 간섭도와 같이 저주파 싸인 곡선 형태의 위상 패턴이 그대로 남아 있으며 이는 이온층에 의한 오차 보정이 제대로 수행되지 않았음을 의미한다. 이에 반해, 제시된 방법을 적용한 결과 간섭도 전체에서 특정 패턴이 없어졌으며 비행방향을 따라 ${\pm}1rad$ 내의 안정된 위상 값을 유지하며 이온층에 의한 레이더 간섭도의 위상 왜곡 보정 적용이 잘 되었다. 제안된 방법은 효과적으로 이온층에 의한 위상 오차를 보정함으로써 L- 혹은 P-밴드 시스템의 레이더 간섭도 정확성과 활용성을 높일 수 있는 중요 기술이 될 것이다.

• 한국우주과학회:학술대회논문집(한국우주과학회보)
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• 한국우주과학회 2011년도 한국우주과학회보 제20권1호
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• pp.30.2-30.2
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• 2011

In this report, we present in-orbit radiometric performance prediction for the Amon-Ra (Albedo Monitor and Radiometer) energy channel instrument. The Integrated Ray Tracing (IRT) computational technique uses the ray sets arriving at the Amon-Ra instrument aperture orbiting around the L1 halo orbit. Using this, the variation of flux arriving at the energy channel detector was obtained when the Amon-Ra instrument including the energy channel design observes the Sun and Earth alternately. The flux detectability was verified at the energy channel detector (LME-500-A, InfraTecTM). The detector time response and RMS signal voltage were then derived from the simulated flux variation results. The computation results demonstrate that the designed energy channel optical system satisfies the in-orbit detectability requirement. The technical details of energy channel instrument design, IRT model construction, radiative transfer simulation and output signal computation results are presented together with future development plan.

• 한국지하수토양환경학회지:지하수토양환경
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• 제20권1호
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• pp.65-75
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• 2015

An artificial recharge test aimed at investigating transport characteristics of the injected water plume in a fractured rock aquifer was conducted. The test used an injection well for injecting tap water whose temperature and electrical conductivity were different from the groundwater. Temporal and depth-wise variation of temperature and electrical conductivity was monitored in both the injection well and a nearby observation well. A highly permeable fracture zone acting as the major pathway of groundwater flow was distinctively revealed in the monitoring data. A finite element subsurface flow and transport simulator (FEFLOW) was used to investigate sensitivity of the transport process to associated aquifer parameters. Simulated results showed that aperture thickness of the fracture and the hydraulic gradient of groundwater highly affected spatio-temporal variation of temperature and electrical conductivity of the injected water plume. The study suggests that artificial recharge of colder water in a fractured rock aquifer could create a thermal plume persistent over a long period of time depending on hydro-thermal properties of the aquifer as well as the amount of injected water.

• 한국연초학회지
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• 제10권1호
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• pp.65-73
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• 1988

The fragilities of the tobacco has been considered to be one of the most Important factor in determing not only the quality of the tobacco but also the economic effect to cigarettes manufacturing. The three blender methods to determine relative fragilities were compared with the Korea Tabacco & Ginseng Research Institute Standared Fragilities Test in order to established a suitable method for measuring the fragilities of Korea tobacco leaves. Fragilities measurement by the blender methods expressed either sieve aperture or fineness index and a statistical comparison of the three blender methods was made to short the mirror variance, standard deviation, coefficient of variation, slope, correlation, sensitivity index, etc.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2002년도 하계학술대회 논문집
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• pp.18-21
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• 2002

As the mask design rules get smaller, the probability of the process failure becomes higher due to the narrow overlay margin between the contact and metal interconnect layers. To obtain the minimum process margin, a tabbing and cutting method is applied with the rule based optical proximity correction to the metal layer, so that the protection to bridge problems caused by the insufficient space margin between the metal layers can be accomplished. The side-lobe phenomenon from the attenuated phase shift mask with the tight design nile is analyzed through the aerial image simulation for test patterns with variation of the process parameters such as numerical aperture, transmission rate, and partial coherence. The corrected patterns are finally generated by the rules extracted from the side-lobe simulation.

• 한국전기전자재료학회논문지
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• 제23권4호
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• pp.287-292
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• 2010

Effect of conductance factors on performance of vacuum system was simulated for optimum design of vacuum system. In this investigation, the feasibility of modeling mechanism for VacSim$^{Multi}$ simulator was proposed. Application specific design of vacuum system is required to meet the particular process conditions for various industrial implementations of vacuum equipments. Geometry and length, diameter of exhaust pipeline were modeled as simulation modeling variables for conductance effects. Series vacuum system was modeled and simulated with varied dimensions and structures of exhaust pipeline. Variation of pipeline diameter showed the more significant effects on vacuum characteristics than that of pipeline length variations. It was also observed that the aperture structure of pipeline had the superior vacuum characteristics among the modeled systems.