• 한국지반공학회논문집
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• 제28권9호
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• pp.47-55
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• 2012

본 연구에서는 폐어망 보강형식에 따른 폐타이어-저회 혼합토의 전단특성을 고찰하였다. 실험에 사용된 혼합토는 폐타이어(분말입경 2mm~10mm)와 저회를 동일한 무게비로 구성하였으며, 준비된 혼합토에 폐어망 보강 시 층수와 겹수를 달리하여 보강함으로써 5종류의 시편(무보강 혼합토, 1층 혹은 2층 보강 혼합토, 2겹 1층 혹은 2층 보강 혼합토)이 만들어졌다. 직접전단시험을 수행한 결과 폐어망 보강 혼합토의 역학적 특성은 폐어망 보강 층수와 보강 겹수에 크게 의존하는 것을 알 수 있다. 폐어망 보강 층수와 보강 겹수가 증가함에 따라 혼합토의 전단강도와 내부마찰각은 증가한다. 이것은 보강된 폐어망과 혼합토 입자간의 마찰 및 억물림 효과에 기인하는 것으로 판단된다.

• Geomechanics and Engineering
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• 제24권5호
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• pp.431-441
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• 2021

Rock-socketed drilled shafts are widely used to transfer the heavy loads from the superstructure especially in mountainous area. Extensive research has been done on the behavior of rock-socketed drilled shafts under compressive load. However, little attention has been paid to uplift behavior of drilled shaft in rock, which govern the overall behavior of the foundation system. In this paper, a series of centrifuge tests have been performed to investigate the uplift response of rock-socketed drilled shafts. The pull-out tests of drilled shafts installed in layered rocks having various strengths were conducted. The load-displacement response, axial load distributions in the shaft and the unit skin friction distribution under pull-out loads were investigated. The effects of the strength of rock socket on the initial stiffness, ultimate capacity and mobilization of friction of the foundation, were also examined. The results indicated that characteristics of rock-socket has a significant influence on the uplift behavior of drilled shaft. Most of the applied uplift load were carried by socketed rock when the drilled shaft was installed in the sand over rock layer, whereas substantial load was carried by both upper and lower rock layers when the drilled shaft was completely socketed into layered rock. The pattern of mobilized shaft friction and point where the maximum unit shaft friction occurred were also found to be affected by the socket condition surrounding the drilled shaft.

• 한국구조물진단유지관리공학회 논문집
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• 제28권1호
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• pp.90-97
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• 2024

이 연구에서는 3D 프린팅용 HDCC를 활용하여 패류 껍질의 적층형 결합구조를 모사한 1방향 슬래브의 휨 성능을 평가하였다. 휨 성능 평가를 위하여 일반 콘크리트(RC) 및 HDCC로 일체 제작된 슬래브(HDCC)와 HDCC로 제작된 슬래브 내부에 PE-mesh를 삽입하여 층상형 구조를 모방한 슬래브(HDCC-M)를 제작하여 4점 재하 휨 실험을 수행하였다. 실험결과 HDCC-M 슬래브 실험체의 내력은 RC 및 HDCC 슬래브 실험체 대비 각각 1.7배 및 1.2배 높은 결과를 나타내었다. 또한, 항복 변위와 최대처짐량의 비율로 변위 연성비를 평가한 결과, HDCC 슬래브 실험체가 가장 우수한 값을 나타내었다. 이는 삽입된 PE-mesh로 인해 층을 분리하여 연성을 증가시키는 동시 mesh 체눈을 관통하는 각주형 HDCC가 로 내력손실을 방지하였기 때문이라고 판단된다.

• 한국지하수토양환경학회지:지하수토양환경
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• 제13권4호
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• pp.8-21
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• 2008

지질 매체의 층상 불균질성과 지하수 양수 방식이 해안 대수층 내에서의 지하수 유동과 염분 이동에 미치는 영향을 정량적으로 분석하기 위하여 수리동역학적 분산 수치 모델을 이용한 일련의 삼차원 수치 모델링이 수행되었다. 해수 침투에 대한 층상 불균질성의 영향을 평가하기 위하여 하부 사토층(대수층)과 상부 점토층(준대수층)으로 구성된 층상 불균질 해안 대수층과 이에 상응하는 등가의 물질로 구성된 균질 해안 대수층을 수치 모델링하였다. 또한 해수 침투에 대한 지하수 양수 방식의 영향을 평가하기 위하여 전체 수치 모델링 기간 동안에 동일한 양의 지하수를 양수하는 연속적인 지하수 양수 방식과 두 개의 주기적인 지하수 양수 방식을 상기한 두 해안 대수층에 적용하였다. 수치 모델링 결과는 주기적인 지하수 양수 방식이 층상 대수층의 하부 사토층뿐만 아니라 상부 점토층에서의 지하수 유동과 염분 이동에 보다 중대한 악영향을 끼치며, 주기적인 지하수 양수 시에 양수 강도가 클수록 지하수 염수화가 공간적 및 시간적으로 더욱 심화됨을 보여준다. 이는 해수 침투에 의한 지하수 염수화를 최소화하기 위해서는 지속적인 지하수 양수 방식이 보다 더 적합할 수 있음을 의미한다. 또한 수치 모델링 결과는 주기적인 지하수 양수시에 상부 점토층에서의 지하수 염수화 양상이 하부 사토층에서의 그것에 비해 매우 다르게 발생함을 보여준다. 이러한 두 지층 사이의 지하수 염수화 양상의 차이는 층상 해안 대수층의 층상 불균질성에 기인하는 것으로 해석된다.

• 자원환경지질
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• 제20권2호
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• pp.85-95
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• 1987

The host rocks of titaniferous magnetite deposits in Gonamsan are alkaline gabbros, which are typical of undersaturated alkaline rocks in terms of the lack of normative quartz. According to field occurrences and petrographic features, these alkaline gabbros are divided into 3 rock types: coarse-grained and pegmatitic rock, medium-grained rock with equigranular texture, and layered cumulate rock. All these rocks mainly contain clinopyroxene(salite), plagioclase(An 43-66), pargasite, and ilmenite. The accessory minerals are apatite, sphene, quartz, and sometimes titaniferous magnetite. Pargasite, sphene, and quartz are considered to be secondary minerals formed by the reaction among clinopyroxene, plagioclase and Fe-Ti oxide at deuteric stage. Fe-Ti oxides generally occur as ilmenite in the alkaline rocks, and titaniferous magnetite in the ore deposits. Layered cumulate rocks are characterized by a recurrence of discontinuous thin mesolayer of clinopyroxene-pargasite within leucolayer mainly composed of plagioclase. Clinopyroxene is cumulus mineral whereas plagioclase, ilmenite and apatite occur as intercumulus minerals. According to the variation diagrams of oxide and trace element contents against the differentiation index, incompatible elements, such as Na, Ba and Sr, show positive correlations whereas compatible elements, such as Mg and Cr, show negative correlations. However some compatible elements, such as Co, Ni and V show irregular variations, reflecting relative cumulate status of cumulus and intercumulus minerals. On the de la Roche multicationic diagram, these alkaline gabbros are distributed along the differentiation curve of undersaturated alkaline series from alkaline basaltic composition through basanitic composition to tephritic composition. Layered cumulate rocks, which are distributed between basanitic composition and tephritic composition, reflect their cumulate character, slightly scattering away from the curve. The medium-grained rock shows higher contents in Ba, Sr and light rare earch elements than the coarse-grained and pegmatitic rock. The former shows two times higher contents of total rare earth elements than the latter, $while(La/Lu)_{cn}$ ratios maintain fairly constant values of 5.08~5.06 in these two rocks. This means that coarse-grained and pegmatitic rock, as compared with the medium-grained rock, was formed by the earlier differentiated magma but rare-earth element distribution pattern remained almost parallel during differentiation. From the data the above mentioned, these alkaline gabbros are considered to be comagmatic and to be formed by intrusions of differentiated magmas in its reservoir.

• Parasites, Hosts and Diseases
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• 제23권2호
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• pp.269-284
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• 1985

The metabolism of Entamoeba histolytica would be affected by various environmental factors, and alteration of the environment was known to afEect the fine structure of 5. histolytica. The present study was designed electronmicroscopically to investigate the ultrastructure and enzyme activities in the aEonic and conventional strains of 5. histolytica. The trophozoites of axenically cultivated HK-9 strain and conventional YS-27 and YS-49 strains of 5. histolytica were collected and liKed with 4% paraformaldehyde/0.1M cacodylate buffier(pH 74), After washing them by centrifugation, 1% warm agar was added in the sediment. Solidified agar with the trophozoites was cut into $lmm^3$ cubes, and incubated in the various substrates to observe enzyme activities. Then, the specimen was post-fixed with 3% glutaraldehyde/0.1M cacodylate buffer (PH 7.4) and 1% osmium tetroBide/0.1M cacodylate buffier (pH 7.4) , dehydrated in ascending ethanol series and embedded in epoxy resin. These were sectioned on an ultramicrotome and observed with a transmission electronmicroscope. The procedures for the observation of the fine structure were same as the above, except for the incubation in the substrate. The sections were stained with uranyl acetate and lead citrate. For the observation of the surface of the amoebae, scanning-electronmicroscopy was carried out. The results obtained in the present study are summarized as follows: 1. The fuzzy coat around double-layered plasma membrane of 5. histolytica was more irregularly and densely distributed in the conventional strains (YS-27, YS-49 strains) than in the axonic strain (HK-9 strain). 2. The endosomes, button bodies and chromatin material were surrounded by a double-layered nuclear membrane having scattered nuclear fores. The paranuclear body, mono- or double-layered vacuoles, vacuolar membrane whorls, rosette-like cylindrical bodies, aggregation of cylindrical bodies and helical bodies were found in the cytoplasm of the amoebae. Helical bodies and glycogen granules were generally abundant, while a few smooth endoplasmic reticula were observed in the cytoplasm. 3. Alkaline phosphatase activity was mainly demonstrated in the plasma membrane, limiting membranes of vacuoles and smooth endoplasmic reticula. ATPase activity was observed in the nucleus, limiting membranes of vacuoles and vacuolar membrane whorls. 4. Acid phosphatase activity was commonly demonstrated in the limiting membranes an contents of vacuoles, Iysosome-like organelles, plasma membrane and the button bodies in the nucleus. The activity was more weakly demonstrated in the HK-9 strain than in the other conventional strains of 5. histolytica. No peroBidase activity was observed in the amoeba strains employed in the present study. 5. With a scanning electron-microscope, no distinct structural differences were observed between the amoeba strains. All the trophozoite forms of the amoebae showed crater-like depressions and rugged features on the outer surface.

• 한국음향학회지
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• 제39권4호
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• pp.270-278
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• 2020

본 논문은 원통형 임피던스 튜브내에 설치된 다중 미세천공판(Micro-Perforated Plate, MPP)의 음향투과를 해석적으로 구하는 방법을 다루었다. 판의 진동을 무한 급수의 합으로 전개하였는데 반경방향으로는 Bessel 함수를 포함한다. 평면파 가정하에서 저주파수 대역의 근사식을 유도하였으며 전달함수법을 이용하여 다중 MPP에 대한 음향투과율 공식을 제시하였다. 단일과 이중 MPP의 음향투과손실(Sound Transmission Loss, STL)을 본 논문에서 제안한 공식을 이용하여 계산하였으며 유한요소법(Finite Element Method, FEM)을 사용한 결과와 잘 일치 하였다. 천공율이 증가할수록 STL은 감소하는데 이는 판의 진동보다는 천공율이 더 큰 영향을 주기 때문이다. STL은 판의 공진주파수에서 골(dip)을 보이며 이중 MPP의 STL은 질량-스프링-질량 진동에 해당하는 공진주파수에서 골을 보인다. 본 연구에서 제안한 STL 예측 모델은 임의의 개수의 다중 MPP에 적용이 가능하며 각각의 판은 미세천공을 포함하거나 포함하지 않는 두 가지 경우가 모두 가능하다.

• Membrane and Water Treatment
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• 제9권6호
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• pp.455-462
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• 2018

The measurement and monitoring of the biochemical oxygen demand (BOD) play an important role in the planning and operation of wastewater treatment plants. The most basic method for determining biochemical oxygen demand is direct measurement. However, this method is both expensive and takes a long time. A five-day period is required to determine the biochemical oxygen demand. This study has been carried out in a wastewater treatment plant in Turkey (Hurma WWTP) in order to estimate the biochemical oxygen demand a shorter time and with a lower cost. Estimation was performed using artificial neural network (ANN) method. There are three different methods in the training of artificial neural networks, respectively, multi-layered (ML-ANN), teaching learning based algorithm (TLBO-ANN) and artificial bee colony algorithm (ABC-ANN). The input flow (Q), wastewater temperature (t), pH, chemical oxygen demand (COD), suspended sediment (SS), total phosphorus (tP), total nitrogen (tN), and electrical conductivity of wastewater (EC) are used as the input parameters to estimate the BOD. The root mean squared error (RMSE) and the mean absolute error (MAE) values were used in evaluating performance criteria for each model. As a result of the general evaluation, the ML-ANN method provided the best estimation results both training and test series with 0.8924 and 0.8442 determination coefficient, respectively.

• 지질공학
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• 제6권1호
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• pp.33-43
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• 1996

본 연구에서 세 성분 단일 관측을 이용해서 국지와 광역 지진 및 폭발외 진원 깊이, 진원시등을 재결정 했다. 우리는 진원 방위각, 시범 지진 진앙이 산출될 수 있느 편파분석 방법예 의하여 이 연구를 수행하려고 한다.일정한 층속도 모텔에 기초를 두고 이론적 주시표가 각 이벤트 입력 지진 위상들에 맞도록 계산 될 수 있다. 지진 규모는 P파 코다(coda)의 지속시간을 이용해서 결정한다. 최소 오차에 대응하는 결과는 이 연구소에서 모두 지진의 평균 깊이는 15km 이라는 것을 보여주는데 이것은 다른 연구소 조사와 매우 일치함을 알 수 있다(Kang and Choi, 1993).

• Journal of Advanced Research in Ocean Engineering
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• 제1권4호
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• pp.211-226
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• 2015

Membrane type Mark III cargo containment system (CCS) is considered in this study to investigate its strength capability under applied loads due to liquefied natural gas (LNG) cargo. A rectangular plated structure supported by inner hull structure is exemplified from Mark III CCS according to classification society's guidance and it is assumed as multi-layered structure by stacking plywood, triplex, reinforced polyurethane (PU) foam and series of mastic upon inner hull structure. Commercially available general purpose finite element analysis package is used to have reliable FE models of Mark III CCS plate. The FE models and anisotropic failure criteria such as maximum stress, Hoffman, Hill, Tsai-Wu and Hashin taking into account the direction dependent material properties of Mark III CCS plate components and their material properties considering a wide variation of temperature due to the nature of LNG together form the strength analysis procedure of Mark III CCS plate. Strength capability of Mark III CCS plate is understood by its initial failure and post-initial failure states. Results are represented in terms of failure loads and locations when initial failure and post-initial failures are occurred respectively. From the results the basic design information of Mark III CCS plate is given.