• Geomechanics and Engineering
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• 제23권4호
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• pp.381-392
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• 2020

The difficulties, challenges and limitations faced in standard pressuremeter testing in the measurement of low soil deformations led a number of researchers to think about the possible modification of the equipment, and especially the replacement of the volumeter by a Hall Effect sensor. This article is a major contribution in this direction. It makes an attempt to detail the design, manufacture and operation of the new equipment. The calibration of the various components was carried out according to the rules presently in force. This proposal was applied, on an exploratory basis, to the data of a real site located in France. The authors present the preliminary results of some cyclic pressuremeter tests, previously carried out in the laboratory, on a sandy material, and they then provide a basic interpretation of these results. The findings indicated that the proposed apparatus is capable of providing high-quality information about constraints and deformations. Although these tests were performed within the laboratory, it was possible to analyze the power, quality, performance and insufficiencies of the proposed equipment.

• 한국기계가공학회지
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• 제18권5호
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• pp.1-8
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• 2019

Breath analysis using a portable device is better than the classical breath analysis system in terms of installation and operation. There is an increasing need to develop cost-effective equipment for testing gas sensors from the viewpoint of functionalities that can be applied applicable to portable devices. In the present study, an economical gas chamber for in-situ gas measurement is implemented with a single gas chamber without using expensive gas storage and control equipment; the gas response characteristics are analyzed using the above-described chamber. The main features of the implemented gas chamber are simple injection procedure, improved gas diffusion, easy measurement and cleaning, support for low-power mode measurement function for portable devices, and open source platform. Moreover, an analysis of gas response characteristics based on changes in sensor voltage show that the sensitivity and 90% response time are affected by the sensor voltage. Furthermore, the sensitivity graph has an inflection point in a specific range. The gas sensor applied in this study showed fast response speed and high sensitivity for sensor voltages of 3.0-3.5 V, regardless of the concentration of acetone gas, the target gas used in this study.

• Current Applied Physics
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• 제18권11호
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• pp.1388-1392
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• 2018

Metal thin films are used widely to solve the vibration problem. However, damping mechanism is still not clear, which limits the further improvement of the damping properties for film and the development of multi-functional damping coating. In this paper, Damping microscopic mechanism of porous metal films was investigated at both macroscopically and microscopically mixed levels. Molecular dynamics simulation method was used to model and simulate the loading-unloading numerical experiment on the micro-pore and vacancy model to get the stress-strain curve and the microstructure diagram of different defects. And damping factor was calculated by the stress-strain curve. The results show that dislocations and new vacancies appear in the micro-pores when metal film is stretched. The energetic consumption from the motion of dislocation is the main reason for the damping properties of materials. Micro-mechanism of damping properties is discussed with the results of in-situ experiment.

• 터널과지하공간
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• 제18권2호
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• pp.91-97
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• 2008

본 고에서는 공동굴착에 따른 주변 영향영역 암반의 투수 특성 변화를 간접적 방법이 아닌 직접적으로 측정 가능한 현장수리시험장비를 소개하고 국내 지하연구시설(URL) 현장실험에 적용한 결과를 수록하였다. 굴착공동 주변 수리학적 EDZ의 투수계수 측정의 정밀도 향상을 위해서는 잘 설계된 시험장비와 함께 시험결과를 분석 평가하는 기술이 통합된 시스템 개발이 필요할 것으로 생각된다. 이를 통해 지하수면 아래 건설되는 공동의 안정성 평가, 방배수 시스템 및 그라우팅 설계의 신뢰도 향상에 기여할 수 있을 것으로 기대된다.

• 지구물리
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• 제6권2호
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• pp.79-87
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• 2003

An in-situ four-electrode contact resistivity probe system was designed, and field-tested in submarine sediments. Seismic survey was also performed to support and compare the results of electric survey. The probe was designed to be driven to selected depths below the seafloor using a Vibracore system. The four insulated electrodes were, spaced equidistant across the wedge, were extended beyond the probe tip to minimize effects of sediment disturbance by the wedge insertion. In-situ measurements of resistivity were recorded on board by precision electronic equipment consisting of signal generators and processors, and by temperature- monitoring systems. Overall limits of uncertainty at respective depths below the seafloor are up to ±10% of the measured values. Best estimates of conductivity are considered to be ±3 percent of the reported values. Resistivity measurements were made at six sites in carbonate sediments to a maximum depth of penetration of about 5 m. Average values of conductivity range between 0.88 and 1.21 mho/m. The results show the seabed is composed of alternating layers of relatively high-conductivity material (0.8 to 1.4 mho/m) in thicknesses of more or less one meter and layers about 30 cm thick having relatively low conductivities (0.4 to 0.8 mho/m).

• 한국환경과학회지
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• 제11권12호
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• pp.1333-1337
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• 2002

A significant fraction of nutrients, such as nitrogen and phosphorus released from sediment are utilized by primary production in the shallow water of coast and lake. The purpose of this study is to introduce the mechanism of nutrients release from sediment and to introduce the methods of the measurement of nutrient released from sediment. One approach is to calculate nutrients released from sediment by a concentration gradient between sediment pore waters and overlying water based on the Fick's law. The other approaches of measurement are the undisturbed sediment core experiments and measurement of nutrient released from sediment by the in situ chamber equipment.

• 한국지반신소재학회논문집
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• 제13권4호
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• pp.119-131
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• 2014

본 연구에서는 광역 부지나 현장 접근성이 용이하지 않은 현장의 지반조사를 신속 정확하게 수행하기 위한 목적으로 해외에서 널리 사용되고 있는 동적 콘 관입시험기를 개선한 개량형 동적 콘 관입시험기를 개발하였다. 기존의 동적 콘 관입시험기의 장점인 휴대성, 간단한 시험방법 등은 그대로 반영하는 한편, 하부 로트의 결합 연장을 통하여 기존 시험기의 지반 관입심도 1m에서 6m까지 관입되도록 고안하였다. 또한, 해머(2+3+3kg), 콘(3type) 등의 조합으로 독일식/일본식 간이 동적 콘 관입시험기(Tsukuba, PWRI, SH type)와 동일한 제원으로 시험이 가능하며, 심도가 깊어짐에 따라 시험 결과에 영향을 미치는 수직도를 확보할 수 있도록 보조 장치를 적용시켰다. 이렇게 개발 제작한 개량형 동적 콘 관입시험기의 적용성을 평가하기 위하여 국내/외 현장의 다양한 지반에 대하여 시험을 수행하여 그 신뢰성을 확보하였다.

• 터널과지하공간
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• 제25권6호
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• pp.505-514
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• 2015

본 연구에서는 기존 오염토양 안정화처리 시공방법의 문제점에 대한 해결을 위하여 개발한 혼합포설방식 안정화장비의 현장 적용성 및 시공성을 현장실증시험 및 실내시험을 통하여 검증하였다. 현장 실증시험을 통하여 안정화장비의 현장 적용성을 확인하였으며, 현장 교반토의 석회석 분포 및 CaO 함량 분석 등의 실내시험을 통하여 기존 오염토양 안정화처리 시공방법에 비해 개발된 안정화장비 시공방법의 안정화제 교반성이 더 우수한 것을 확인하였다.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2006년도 심포지엄 논문집 정보 및 제어부문
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• pp.96-98
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• 2006

A new ex-situ model to diagnose a plasma processing equipment was presented. The model was constructed by combining wavelet, scanning electron microscope, ex-situ measurement of etching profile, and neural network. The diagnosis technique was applied to a tungsten etching process, conducted in a $SF_6$ helicon plasma. The wavelet was used to characterize detailed variations of plasma-etched surface. The diagnosis model was constructed with the vertical wavelet component. For comparison, a conventional model was built by using the estimated profile data. Compared to the conventional model, the wavelet-based model, demonstrated a much improved diagnosis.

• 한국관개배수논문집
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• 제8권1호
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• pp.61-69
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• 2001

The Guelph Permeameter (Soil Moisture Equipment Co., 1986) is an in-hole constanthead permeameter, employing the Mariotte Principle. The Guelph Permeameter has been proved to be a useful and versatile instrument for determining the in situ hydraulic prope