• 지구물리와물리탐사
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• 제7권1호
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• pp.62-69
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• 2004

The objective of this study is to estimate the distribution of a zone disturbed by excavation (EDZ) around tunnels that have been excavated at about 500 m depth in pre-Tertiary hard sedimentary rock. One of the most important tasks is to evaluate changes in the dynamic stability and permeability of the rock around the tunnels, by investigating the properties of the rock after the excavation. We performed resistivity and acoustic tomography using two boreholes, 5 m in length, drilled horizontally from the wall of a tunnel in pre-Tertiary hard conglomerate. By these methods, we detected a low-resistivity and low-velocity zone 1 m in thickness around the wall of the tunnel. The resulting profiles were verified by permeability and evaporation tests performed at the same boreholes. This anomalous zone matched a high-permeability zone caused by open fractures. Next, we performed resistivity monitoring along annular survey lines in a tunnel excavated in pre-Tertiary hard shale by a tunnel-boring machine (TBM). We detected anomalous zones in 2D resistivity profiles surrounding the tunnel. A low-resistivity zone 1 m in thickness was detected around the tunnel when one year had passed after the excavation. However, two years later, the resistivity around the tunnel had increased in a portion, about 30 cm in thickness, of this zone. To investigate this change, we studied the relationship between groundwater flow from the surroundings and evaporation from the wall around the tunnel. These features were verified by the relationship between the resistivity and porosity of rocks obtained by laboratory tests on core samples. Furthermore, the profiles matched well with highly permeable zones detected by permeability and evaporation tests at a horizontal borehole drilled near the survey line. We conclude that the anomalous zones in these profiles indicate the EDZ around the tunnel.

• 로봇학회논문지
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• 제18권4호
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• pp.444-455
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• 2023

In this report, a specialization plan for wearable robots by mission profile was investigated and analyzed to derive an application plan. The final goal of this study was to derive the operating requirements of wearable robots according to specialized plans, and to conduct a specialized study on wearable robots by mission profile through investigation/analysis of specialized plans for each mission profile. In the study, 1) Research on technology trends related to military wearable robots such as patents and papers, 2) Research/analysis of mission profiles to characterize wearable robots, 3) Analysis of wearable robot specialization plans according to mission profiles, and 4) Requirements for wearable robot operation were derived. In the first time of the study, a survey on technology trends related to wearable robots for soldiers such as patents and papers was completed, and a military consultative body was conducted to derive measures to characterize wearable robots. In addition, a survey was conducted on mission profiles, and the second time study derived Key Performance Parameters (KPP) for operational performance, core performance, and system performance based on scenarios by mission profile. However, it is revealed that the KPP derived from the research results was not covered in this paper because it was judged that more in-depth research was needed prior to disclosure. In order to prepare for future battlefield situations and increase the usability of wearable robots, this study was conducted to characterize wearable robots by considering the characteristics of soldiers' equipment according to mission profiles and to characterize wearable robots by mission profile.

• ETRI Journal
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• 제21권3호
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• pp.41-48
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• 1999

We have calculated differential reflection coefficient for isolated well structure of micro-scale, etched on dielectric surface. The differential reflection coefficient is computed using Green's second integral theorem. The purpose of our computation is to find a class of well profiles which give maximal diffusive scattering. To have such a maximal effect, we have concluded that the waist radius of Gaussian beam and its wavelength should be comparable to the well width and that well depth has to be larger than a wavelength. Exact calculation of differential reflection coefficients of dielectric surface with isolated structure on it may be used for the examination of dielectric surfaces and also in making simple but efficient diffuser.

• 한국표면공학회지
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• 제22권4호
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• pp.215-220
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• 1989

Silicon Nitride whose thickness is about $100\AA$by the ellipsometer was successfully formed by the Plasma reaction. Nitrogen Plasma was formed by applying the 200KHz, 500Watt power between the two electroes and nitridation of silicon was carried out directly on the top of the silicon wafer. Thus Silicon Nitride formed was oxidized to from oxynitrides and their electrical characterlstice were analyzed by measuring I-V curves and capacitances. Through ESCA depth profiles, the chemical composition changes before and after the oxidation wers analyzed.

• 한국윤활학회:학술대회논문집
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• 한국윤활학회 2002년도 proceedings of the second asia international conference on tribology
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• pp.67-68
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• 2002

The properties and mechanism of silicon protuberance and groove processing by diamond tip sliding using atomic force microscope (AFM) in atmosphere were studied. To control the height of protuberance and the depth of groove, the processed height and depth depended on load and diamond tip radius were evaluated. Nanoprotuberances and grooves were fabricated on a silicon surface by approximately 100-nm-radius diamond tip sliding using an atomic force microscope in atmosphere. To clarify the mechanical and chemical properties of these parts processed, changes in the protuberance and groove profiles due to additional diamond tip sliding and potassium hydroxide (KOH) solution etching were evaluated. Processed protuberances were negligibly removed, and processed grooves were easily removed by additional diamond tip sliding. The KOH solution selectively etched the unprocessed silicon area. while the protuberances, grooves and flat surfaces processed by diamond tip sliding were negligibly etched. Three-dimensional nanofabrication is performed in this study by utilizing these mechanic-chemically processed parts as protective etching mask for KOH solution etching.

• 한국자기학회지
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• 제20권4호
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• pp.160-166
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• 2010

엑스선 공명 자기산란은 엑스선 반사율과 회절의 원리를 이용하여 자기 다층박막 내 깊이 방향의 자화 모양 및 자기 나노 구조체 내의 자화 분포를 특정 원소별로 구할 수 있다. 여기서는 엑스선 공명 자기산란에 대한 간단한 설명과 이를 이용한 자성 다층박막 및 나노 구조체의 자기 구조와 자기 스위칭의 연구에 대하여 몇 가지 예를 들어 설명하려 한다.

• 한국군사과학기술학회지
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• 제18권5호
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• pp.548-557
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• 2015

This paper is results on Chemisorption of organic compound for the sea water fire fighting line of naval vessels. The quantitative analysis of Chemisorption has been investigated in seawater after immersion in 0.1 % of NaDDTC solutions for 43 hours. The morphology and topography were investigated by FE-SEM and AFM. The chemical elements were analyzed by SEM-EDS, XPS and the depth of chemical elements was measured by depth profiles. The effect of NaDDTC comes from Chemisorption between Copper and Sulfur of NaDDTC. As a result, test results showed that sulfur is helpful to protect a corrosion of seawater line.

• Biotechnology and Bioprocess Engineering:BBE
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• 제6권5호
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• pp.352-358
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• 2001

Because algal cells are so efficient at absorbing incoming light energy, providing more light energy to photobioreactors would simply decrease energy conversion efficiency. Furthermore, the algal biomass productivity in photobioreactor is always proportional to the total photosynthetic rate. In order to optimize the productivity of algal photobioreactors (PBRs), the oxygen production rate should be estimated. Based on a simple model of light penetration depth and algal photosynthesis, the oxygen production rate in high-density microalgal cultures could be calculated. The estimated values and profiles of oxygen production rate by this model were found to be in accordance with the experimental data. Optimal parameters for PBR operations were also calculated using the model.

• Journal of Advanced Marine Engineering and Technology
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• 제32권6호
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• pp.901-907
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• 2008

The measurements of velocity vectors are made in the wake(X/d=8) of a circular cylinder with arc grooves. The experiments are conducted by changing the groove number. groove depth, Reynolds number(Re) and the angle of the first formed groove. We know that the optimum groove angle is 70 degree and the wake velocity profiles are improved at a few conditions. According to vortex shedding frequency distributions. the key solutions to vary the flow field behind the circular cylinder are 70 degree groove angle and more deeper grooves than 0.2mm depth.

• The Journal of the Acoustical Society of Korea
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• 제23권2E호
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• pp.68-73
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• 2004

In the East Sea of Korea, the ocean environments are known to have strong variations in space and time. Their effects are very important factors in sound propagation and sonar performance. We consider the environmental factors such as eddies and thermal fronts affecting underwater sound propagation and target detection performance by sonars. Unfortunately, however, the detailed structure of eddies is usually difficult to understand by using the sea surface temperatures from infrared images alone or a few profiles from the CTD (conductivity, temperature and depth) castings. The temperature fields of eddy and thermal front are simulated with typical patterns of those obtained from several observations. This paper delivers the overviews of environments and acoustic models with their simulation results on sonar performance.