• 지질공학
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• 제11권3호
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• pp.245-254
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• 2001

처분덮개는 중.저준위 방사성폐기물 천층처분시설의 성능 유지에 중요한 역할을 하므로 여러가지 시험과 장기관측을 통한 처분덮개의 성능실증 연구는 시설의 안전성 확보에 불가결한 요소이다. 처분덮개의 기본적인 성능요건으로는 불투수성, 건전성, 열화에의 저항력 및 유지보수의 용이성 등을 고려할 수 있다. 이러한 성능요건을 단일층으로는 충족하기 어려운 점을 고려하여 HELP(Hydrologic Evaluation of Landfill Performance) 코드를 사용한 물수지 평가를 통해 상부 보호층, 중간 배수층 및 하부 저투수층 등으로 구성된 다층덮개 개념을 도출하였다. 처분덮개 내에서의 수분이동특성을 규명하기 위해 TDR(Time Domain Reflectometry)과 Tensiometer를 사용하여 각각 함수비와 matric potential의 변화를 3$\times$3$\times$3.3m 크기의 6개 시험고에서 장기관측 할 수 있도록 설계하였다.

• 한국지반환경공학회 논문집
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• 제4권1호
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• pp.19-28
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• 2003

통상 콘크리트 옹벽에 작용하는 수평토압 산정에는 Rankine이나 Coulomb의 토압이론을 사용하고 있으나 문헌연구결과, 실제 옹벽 벽체에 발생하는 변위인자에 의한 영향으로 벽체 중단부 이상에서는 주동토압 상태를 나타내고 있으나 벽체 중단부 하단에서는 주동토압보다 큰 토압을 가지고 있다. 본 연구에서는 이와 같은 수평토압을 저감하기 위한 방안의 하나로 압축성 재료인 EPS를 벽체 배면에 설치하여 배면토체의 변위를 인위적으로 유발함으로서 수평토압의 크기를 저감시킬 수 있는 방안을 제시하였다. EPS에 의한 수평토압 저감효과, 최적의 EPS 포설두께 및 밀도를 알아보기 위한 실내모형토조시험을 실시하였으며 그 효과가 검증되었다. 실내모형토조시험에서 도출된 결과를 이용한 현장 시험시공결과, EPS 포설에 의해 약 20%의 수평토압저감효과를 가질 수 있는 것으로 평가되었다.

• 식물분류학회지
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• 제40권4호
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• pp.218-225
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• 2010

덕유산 (1614 m)에서 우리나라 미기록 태류식물 10 분류군을 발견하였다. 미기록속인 엄마이끼과의 창이끼 [Tetralophozia filiformis (Steph.) Urmi]와 미기록종인 쌍갈고리이끼과의 왕쌍갈고리이끼 [Herbertus buchii $Jusl{\acute{e}n$], 벼슬이끼과의 선좀벼슬이끼 [Bazzania japonica (Sande Lac.) Lindb.], 겉게발이끼과의 산겉게발이끼 [Cephaloziella hampeana (Nees) Schiffner ex Loeske.], 망울이끼과의 꼬마망울이끼 [Jungermannia japonica Amak.], 은비늘이끼과의 고산양끝통이끼 [Marsupella alpina (Gott. ex Husn.) Bernet.], 날개이끼과의 숲누운날개이끼 [Pedinophyllum interruptum (Nees) Kaal.], 지네이끼과의 푸른지네이끼[Frullania polyptera Tayl.], 가시지네이끼과의 계곡가시이끼 [Jubula hutchinsiae ssp. javanica (Steph.) Verd.], 우산이끼과의 고산우산이끼[Marchantia polymorpha ssp. montivagans Bischl. and Boisselier-Dubayle.]는 덕유산 계곡 및 능선부에 소수의 개체가 자생하고 있었다.

• 한국철도학회논문집
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• 제9권1호
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• pp.118-124
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• 2006

SThe rigidities of bridge substructures are the important data in the rail-bridge interaction analysis in Korean High -Speed Railway. This experimental study is being performed because of followings. 1) More correct longitudinal stiffness of the structure including substructure should be considered in the calculation of stresses in rails. 2) There are many uncertainties in the design and construction of the piers and foundations. 3) Actual guideline for the rigidities of piers and foundations in the design is necessary. 4) Measurement on the rigidity of pier according to the types of piers, foundations and soil-conditions is needed. Curve for estimating the total rigidity of substructure will be obtained through this and further experimental studies. It may be used in the analysis of Korean High-Speed Railway bridge and then, longitudinal stresses in the rails can be estimated more accurately. One pair of piers, which consist of pot-bearing for fixed support and pad-bearing for movable support, are loaded by steel frame devices with steel wire ropes and hydraulic jack. The responses which are measured at each loading stages in those field tests are displacements and tilted angles on the top and bottom of piers. This study is being performed testing and analysis about several piers in the construction field.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2001년도 춘계학술대회 논문집
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• pp.451-458
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• 2001

The purpose of this study was to evaluate shear parameters on cutting slope of weathered granite soils by using small dynamic cone penetration test on the very moment of its cutting. The results were : On the relations among N$\_$c/, Li, and CEC, the condition of Li＞6%, CEC＞14(meq/100g) corresponds to that of N$\_$c/ values of 2∼30, and 3＜CEC＜14(meq/100g) to N$\_$c/=30∼50. Comparing the smallest penetration depth from two small dynamic cone penetration tests done at 5m below from the top of the slope on April 15th, October 31t. there was a l0cm difference. So we could find out the degree of weathering on the slope. And dividing the difference by 190 days (the whole testing time), we could know it's being weathered 0.052mm each day. The more N. value increases, the more shear parameters(internal friction angle ; $\phi$, cohesion : c) increase at a standard pressure($\sigma$＞32㎪). So the condition of N$\_$c/=2∼50 corresponds to that of $\phi$=27∼50, c=12∼49㎪. From the above testing results, the N$\_$c/ values more correspond to $\phi$ values than c values. In conclusion, this study suggests that on small dynamic cone penetration test a penetration boundary line of 5 centimeters is decided at around Li=4%, CEC=3(meq/100g) which is classified as a strong weathering soil. It also shows that as Li increases CEC increases as well, while N$\_$c/ decreases.

• 한국지반환경공학회 논문집
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• 제15권5호
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• pp.57-65
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• 2014

경제적, 기술적인 이유에서 실내시험을 위한 in situ 상태 그대로의 현장 모래 시료를 채취하는 것은 매우 어렵다. 따라서 현장과 유사한 상태의 시료 조성을 위한 다양한 시료 재성형 방법이 제시되었으며, 연구 목적에 따라 적합하다고 판단되는 시료성형방법이 다양하게 적용되고 있다. 본 논문에서는 모래의 시료 재성형 시 널리 이용되고 있는 습윤다짐법, 건조낙사법, 그리고 건조퇴적법을 적용하여 동일한 상대밀도로 시료를 조성한 후, 일정한 구속압 조건에서 압밀배수전단 시험을 수행하였다. 또한 자체제작을 통해 시료의 상 하부 캡에 압전소자를 설치하여 압밀 종료 시점과 전단과정에서의 탄성파 속도를 측정함으로써 시료 재성형 방법 및 상대밀도에 따른 오타와 모래에서의 거동 특성 및 전단거동 시의 탄성파 속도의 변화 경향을 분석하였다. 분석 결과, 시료 조성방법에 따라 전단과정에서 모래의 거동에는 차이가 발생할 수 있는 것으로 나타났으며, 전단과정 시 전단파 속도는 체적 변화양상과 동일한 경향을 보이는 것으로 나타났다.

• 한국지반환경공학회 논문집
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• 제9권3호
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• pp.29-34
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• 2008

한국건설기술연구원(KICT)에서는 트리플 코어 바렐의 원리를 적용하여 기존의 연약지반 뿐만 아니라 사질토 및 풍화토 지대에도 적용이 기능한 대구경 샘플러를 개발하였다. 특별히 제작된 시료 절단 및 추출 장치는 다양한 종류의 채취 시료에 적용하여 시료의 교란을 최대한 방지 할 수 있도록 고안되었다. 샘플러 두부에는 적절한 강성의 스프링을 설치하여 슈(shoe)와 비트(bit) 사이의 거리가 변화하도록 하여 대상지반의 강성에 맞추어 효과적인 시료채취가 가능하도록 하였다. 대구경 샘플러의 적용성을 확인하기 위하여 일반적으로 시용되는 피스톤 샘플러와 대구 경 샘플러를 이용해 여러 대상지반에서 채취한 시료의 교란도를 비교 분석하였으며, 다양한 공학적 특성 또한 비교 분석 하였다.

• 아시안잔디학회지
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• 제9권4호
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• pp.285-292
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• 1995

To elucidate the mineral cycles of potassium in a dynamic grassland ecosystem in a steady state condition, this investigation was cunducted along the northwest side on Mt. Kwanak. The exper-imental results may he summarized on communities of Z. japonica and M. sinensis as follows. As compared with some pronerties of the surface soils among two semi-natural grasslands, the levels of exchangeahle potassium were high in M. sinensis and low in Z. japonica. Contents of potassium for the litters of Z. japonica and M. sinensis were 1.69% and 2.51%, re-spectively. The annual production of potassium was 1.32 g /m$m^2$ in the Z. japonica grassland and 3. 08 g /m$m^2$in the M. sinensis grassland. For a case of steady production and release, the ratio of annual min- eral production to the amount accumulated on top of the mineral soil in a steady state provides estimates of the release constant k. The models of the release, accumulation and annual cycle of potassium in a grassland ecosystem are determined by the equation (1) to (3), respectively (Table 3). Since it requires a period of about each 0.693 /r, 3 /r and 5 /r years for the release and accumu-lation of 50, 95 and 99% of its steady-state level, the estimates for potassium in a dynamic grass-land ecosystem of Mt. Kwanak were 1.5, 6.6 and 11.0 years in the Z. japonica grassland, and were 2.7, 11.9 and 19.8 years in the M. sinensis grassland. The amounts of annual cycles for potassium in a grassland ecosystem under the steady-state conditions were 1.32 g /m$^2$ in the Z. japonica grassland and 3.08 g /$m^2$ in the M. sinensis grassland. Key words : ZQvsia japonica Ahscanthus sinensis, Mt. Kwanak, Potassium cycles.

• Ocean Systems Engineering
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• 제2권3호
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• pp.205-215
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• 2012

Recently, interest of offshore structure construction in South Korea is growing as the land space becomes limited for further development and the renewable energy grows to be more attractive for the replacement of the fossil energy. In order for the optimal construction of optimum offshore floating structures, development of safe and economical offshore foundation technologies is a priority. In this study, the large-deformation behavior of a suction pile, which markets are rapidly growing nowadays, is analyzed for three different loading locations (top, middle, and bottom of the suction pile) with three different displacement inclinations (displacement controlled with displacement inclinations of 0, 10, and 20 degrees from the horizontal). The behavior analysis includes quantifications of maximum resistances, translations, and rotation angles of the suction pile. The suction pile with its diameter of 10 m and height of 25 m is assumed to be embedded in clay, sand, and multi layers of subsea foundation. The soil properties of the clay, sand, and multi layers were determined based on the results of the site investigations performed in the West sea of South Korea. As analyses results, the maximum resistance was observed at the middle of the suction pile with the displacement inclination of 20 degrees, while the translations and rotations resulting from the horizontal and inclined pullouts were not significant until the horizontal components of movements at the loading points reach 1.0 m.

• 기술사
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• 제1권1호
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• pp.18-25
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• 1968

Higher yield in rice paddies is greatly dependent on adequately balanced and timely supply of water. A majority of rice paddy in Korea is generally irrigated by rainfall, but in many cases it has to be supplemented by artificial irrigation for optimum rice culture. Although the water requirement of rice plant is for higher Than that of athec crops, submerged condition of rice paddy is not Necessarily required. The moisture requirement of rice plant varies with its growing stages, and it is possible to increase the irrigation efficiency through reduction of water loss due to percolation in rice paddies. An experimental plots were set up by means of sandomized block design with three duplication; (a) All time submerged, (b) Economically controlled, and (c) Extremely controlled. Three different irrigation periods Were (a) Initial sage, (b) Inter-stage, and (c) Yast stage. The topsoil of the three plots were excavated to the depth of 30 cm and then compacted with clay of 6 cm thickness. There after, they were piled up with the excavated top soils, leveled and cored with clay of 6 cm thickness around footpath in order to prevent leakage. The results obtained from the experiments are as follows, 1. There is no difference among the three experiments plots in terms of physical and chemical conditions, soil properties, and other characteristics. 2. Culm length and ear length are not affected by different irrigation methods. 3. There is no difference in the mature rate and 1, 000 grain weight of rice for the three plots. 4. The control plot which was irrigated every three days shows an increased yield over the all the time submerged plot by 17.8 percent. 5. The clay lined plot whose water holding capacity was held 5 days long, needs only to be irrigated every 7 days. 6. The clay lined plot shows an increased yield over the untreated plot ; over all-the-time submerged plot by 18 percent ; extremely controlled plot by 18 percent, and economically controlled plot by 33 percent. 7. It may be saved in water requirement about one Thirds.