• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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• 2004.09a
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• pp.108-112
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• 2004

균열 암반 대수층에 대한 지하수 인공 함양 주입 가능성을 예비적으로 평가하기 위한 시험을 수행하였다. 지하수 인공 함양 주입 시험이 수행된 지역은 경기도 포천군 이동면이며, 이 지역의 지질은 중립내지 조립질 화강암에 해당된다. 시험 정호에 대한 시추공 내부 촬영 결과, 화강암 내에 부분적으로 절리들이 발달되어 있었으며, 대체로 수직적인 절리 발달이 우세하였다. 2개소에서 인공 함양 주입 시험이 100kgf/$\textrm{cm}^2$ 이상의 확장 팩커로 대상공의 상부를 밀폐한 후 시행되었다. 이중 MW-7호 공에서는, 주입 압력을 5 내지 7kg/$\textrm{cm}^2$으로 조절하여 시간당 약 450$\ell$의 평균 주입률로 시험을 수행하였으며, O-7a 호 공에서는 주입 압력을 4kgf/$\textrm{cm}^2$ 내외, 시간당 약 1,740$\ell$의 평균 주입률로 시험을 수행하였다. MW-7호 공의 시험은 3일간 3회에 걸쳐 각 450분, 200분, 414분 동안 시험이 수행되었으며, O-7a호 공에서는 연속적으로 24시간 동안 인공 함양 주입 시험이 수행되었다. 수행된 지하수 인공 함양 주입시험은 적어도 지하수 상류 구배 구간의 지하 수두를 시험이 수행된 이후에도 24시간 이상 유지하는 것으로 평가되었다. 실험을 통해 주입한 양과 주변 관측공의 수위 상승을 단순 검토한 결과 시험이 수행된 지역의 개략적 유효 공극률을 산정 할 수 있었으며, 그 결과, 이 지역 균열 암반의 유효 공극률은 약 3 내지 6% 인 것으로 평가되었다 국내에서 지하수 인공 함양 방식을 균열 암반 대수층에 활용하여, 지속적인 수자원 관리와 수도 공급을 할 수 있는지를 평가하기 위해서는 앞으로 보다 많은 시험수행과 연구를 통한 검증이 요구된다. 까마중, 냉이, 명아주, 둑새풀 등의 생장에 현저한 조해현상을 나타냈다. 이것으로 보아 억새가 타식물의 생장에 영향을 주는 요인물질은 억새의 뿌리에서 분필되는 것으로 생각된다. 옥수수의 뿌리에서 직접 분필하는 물질이나 옥수수뿌리의 분해물질들은 모두 당귀의 생장을 조해하는 경향이 있었다.기존에 제안된 경험식들에 의한 계산결과 보다 균질화 해석법의 결과가 훨씬 정확함을 주목하여야 한다.c의 범위로서 최대값과 최소값은 4차수(four order)의 차이를 보였다. 단열대의 분포 특성을 파악하기 위하여 지구물리검층을 실시하였고, 각 시험에 의해 획득된 결과들과의 비교를 통하여 유동성이 높은 단열들이 규명되었다. 온도검층은 유동성 단열과 일반적인 단열들을 구별하는 좋은 지시자로 나타났다. 그 결과, N70-80$^{\circ}$W.60-85$^{\circ}$NE/SW, N75-80$^{\circ}$W.25-30$^{\circ}$SW, N50-64$^{\circ}$W.60-85$^{\circ}$NE, N35-45$^{\circ}$E.65-75$^{\circ}$SE, 그리고 N65-72$^{\circ}$E.80$^{\circ}$SE/60$^{\circ}$NW의 단열들이 연구지역의 지하수 흐름을 지배하는 뚜렷한 유동성 단열로 규명되었다.eatments. It was resulted from increase of weight of single cocoon. "Manta"2.5ppm produced 22.2kg of cocoon. It is equal to 9% increase in index, as compared to that of c

• Tunnel and Underground Space
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• v.19 no.3
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• pp.213-225
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• 2009

The purpose of the study is to evaluate the effects of chemical weathering on the granite and orthogneiss in Wonju area based on accelerated artificial chemical weathering. The rock samples were scrutinized the variation of index properties and ion exchanges caused by artificial chemical weathering which was implemented with leaching test for 170 days using double soxhlet extractor. The differential weathering and decrease of p wave velocity were obtained by weathering process without significant changes of porosity. In case of granite samples, the uniaxial compression strength was reduced by 20% and 16% for the F-grade and SW-grade, respectively. For MW-grade granite, however, was not able to examine the effect of strength reduction due to lack of sample number. Also, for orthogneiss, it is difficult to compare the values of uniaxial compressive strength between before and after the test because of its strong anisotropy.

• Geophysics and Geophysical Exploration
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• v.21 no.4
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• pp.231-243
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• 2018

Streaming potential (SP) arises from fluid flow through effectively connected pores. From this potential, formation water information as well as fluid flow properties can be estimated. As micro particles being located in boundary between subsurface porous media and fluid are charged to form electrical double layer, fluid flow caused by several reasons generates SP, one of electrokinetic phenomena. Occurrence mechanism of SP is complex and signal strength is relatively weak compared to noise. However, application of self potential survey using SP to monitoring of formation fluid is expanding because of its' convenience of exploration without artificial source and repetitiveness of signal. This paper accounts for the occurrence mechanism of SP studied before, including governing equations and analyzes previous various case studies of SP according to the change of physical properties of materials. It helps to increase understanding about SP and also lays the foundations of the application of SP to fields.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.29 no.1B
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• pp.91-96
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• 2009

Layered double hydroxide is synthesized and used in the arsenate adsorption experiments. The shapes of two materials analyzed by TEM showed that unheated material is amorphous in shape, micro-sized while heat treated material showed more crystallized in shape and nano-sized. X-ray diffraction showed this result more obvious. $N_2$ adsorption-desorption results showed that the materials are mesoporous and the specific surface area of the heated material is more than two times larger than the unheated material. Adsorption of As(V) is expected to be more in the heated material than the unheated material. Kinetic test of arsenate adsorption showed very fast reaction. The reactivity of Fe with As(V) might be the main factor for this result. The reaction kinetic of the heated and the unheated materials were similar and even the adsorption isotherms showed similar results for both materials. Both materials are found to be useful in remediation of soil and groundwater polluted by waste mine tailings consist of high concentration of As(V).

• Journal of Ocean Engineering and Technology
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• v.18 no.5
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• pp.7-14
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• 2004

The interaction of incident manochromatic waves with an array of N surface-piercing porous dual cylindrical structures is investigated in the frame of three-dimensional linear potential theory. The dual cylindrical structure is camposed of concentric two cylinders. The exterior cylinder is porous and the interior cylinder is impermeable. The fluid domain is divided into N+1 regions i.e. a single exterior region and N interior regions. The diffraction potentials in each region representing the scattering of incident waves by an array of porous cylindrical structures are expressed by the Fourier Bessel series. The unknown coefficients in each region are determined by applying the porous boundary condition and continuity of mass flux at the matching boundary. It is found that an array of porous cylindrical structures reduces both the wave forces and the wave run-up, and shows the excellent performance of wave blocking. The results show that various types of breakwater exchanging seawater are prospective by controlling the porosity and the configuration of cylindrical structures.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.19 no.1
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• pp.143-147
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• 2005

In this paper, an axial type brushless DC motor which has double rotors using rare-earth magnet pieces is designed. This kind of motor has shorter axial length and is easier to assemble than the radial type motors. To get enough torque, NdFeB magnet is used and for the cost of production, the magnets are segmented to rectangle or disk shape. To design this motor, a equivalent circuit is adopted and the air-gap density is calculated using 3D finite element method to get exact parameters. The design variables are optimized with genetic algorithm. From the results of the simulations, the reference of the axial type BLDC motors can be obtained.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.28 no.4
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• pp.80-87
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• 2014

This paper suggests the dual-gap for generating power and increasing the torque of a direct-drive permanent magnet synchronous motor in a hybrid-cycle. To consider easy coil winding, we applied a structure of dual-gap for the permanent magnet synchronous motor (PMSM). Because the torque of PMSM with the dual-gap is very large, we are designed the appropriate specifications of the PMSM by selected the appropriate dual-gap slot and poles combination. The prototype model is selected by design theory for increasing torque and maximizing output power of PMSM. And the detailed structure design of the model was designed by the loading distribution method. The PMSM models were analyzed by finite element method. Finally, we have suggested appropriate rotor structure has benefit to further increasing torque and prevent decreasing of the output power in PMSM with dual-gap.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.6 no.4
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• pp.249-258
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• 2001

Compressional wave velocity and electrical resistivity of muddy sediments in the southeastern inner shelf of Korea were studied using nine piston core samples. The acoustic and physical properties were measured with 10 cm depth interval. Sediment structures were examined by x-radiographs of the cored sediments. Subbottom profiles were obtained by a high-resolution acoustic subbottom profiler. Acoustic turbid layers are clearly seen on the profiles, and x-radiographs of the sediments showed degassying structures formed by gas escaping. On the basis of x-radiographic images, velocities, electrical resistivities and physical properties, the sediments are divided into gassy and non-gassy sediments. The presence of gas and degassying structures result in a marked variation in velocity and electrical resistivity. It can be concluded that velocity and electrical resistivity arep arameter to recognize gassy sediment. The velocity is important parameter to indicate gassy sediment.

• Proceedings of the Korean Society for Agricultural Machinery Conference
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• 2017.04a
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• pp.148-148
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• 2017

방역 차량의 약액탱크, 차량의 연료, 워셔액 등의 탱크 내부에는 잔존량을 측정하기 위해 기둥과 floating box로 이루어진 부력식 수위레벨센서가 사용되고 있으나 액체레벨에 따라 float이 상하로 움직이는 측정원리상 차량 주행 중 정확성이 매우 떨어진다(Park et al. 2016). 방역차량이 주행 중 분사할 때, 슬로싱 현상과 방역소독기의 노즐과 펌프에서 발생하는 진동으로 인해 기존의 부력식 센서를 이용한 약제 살포량 측정방법은 정확성이 매우 떨어지는 경향이 있다. 본 연구의 목적은 방역차량이 주행하면서 분사할 때, 수위레벨 센서를 이용한 약제살포량 측정의 정확성을 개선하는 것으로 디지털 칼만필터, Low pass filter와 댐퍼를 제작하여 이용했다. 본 연구에서는 압력식 레벨센서를 이용해 약액탱크의 높이당 단면적과 수위를 측정하여 약제살포량을 계산했다. Python 2.7을 이용해 디지털 칼만필터와 Low pass filter(LPF)를 구현하였으며 3D프린터를 이용해 댐퍼를 제작했다. 실내에서 슬로싱 현상을 인공적으로 만들어 필터와 댐퍼의 수위 측정 정확성 개선효과를 확인 후 실제 방역차량에 부착하여 비포장도로에서 주행하면서 분사할 때 필터와 댐퍼의 효과를 확인하였다. 댐퍼의 공극률(p)을 바꿔가며 수위 측정 정확성 개선효과를 확인하였다. 실내, 현장 실험 결과, 칼만필터가 LPF보다 개선효과가 더 크지만 데이터 50개 처리에 1.71초의 시간지연이 발생했다. 댐퍼는 수위센서를 고정시키고 유체의 운동을 방해하여 이상치와 큰 오차제거에 효과적이었다. 칼만필터와 댐퍼를 동시에 이용할 경우, 수위 측정정확성 $R^2$는 0.9985, 0.9981로 ${\pm}4.3cm$의 범위내에서 수위를 측정할 수 있었다. 필터의 시간지연과 수위 측정정확성을 고려하여 데이터 기록간격을 3초로 설정하면 ${\pm}3cm$이내에서 약탱크 내 수위를 측정할 수 있었다. 공극률(p)가 0.294, 0.291, 0.17에서 측정정확성 $R^2$는 각각 0.9897, 0.9858, 0.9872 로 p가 0.294에서 개선효과가 가장 좋았으나 개선효과의 차이는 크지 않았다.

• Journal of Energy Engineering
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• v.21 no.1
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• pp.55-67
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• 2012

For the development of gas hydrate as new future energy resources, the drilling was carried out at the five locations where have high potential as gas hydrate bearing sediments in Ulleung basin, offshore Korea in 2007. Well log data were obtained from all wells and core data were procured from 3 wells, UBGH1-04, UBGH1-09 and UBGH1-10. In this study, user-friendly software, "KMU GH Logs 2010", is developed and this software is based on the estimation methods developed in previous study for gas hydrate bearing sediments and the properties estimated from UBGH1-04, UBGH1-09 and UBGH1-10. Petrophysical properties in un-cored wells, UBGH1-01 and UBGH1-14, are also estimated by using well log data. Porosity is estimated by density log and gas hydrate saturation is calculated by sonic log and resistivity log. Sedimentary facies are estimated by applying the linear discriminant analysis using both well log and sedimentary facies data from core analysis. It is confirmed that DITM facies and MSS facies appeared signs of gas hydrate disassociation are able to be distinguished by the method.