• The Journal of the Petrological Society of Korea
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• v.21 no.4
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• pp.385-396
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• 2012

Jeju island is the biggest volcanic island in Korea and there are over 455 Quaternary monogenetic volcanoes, of which approximately 373 volcanoes(82.0%) are cinder cones. Other volcanic forms in the island include sharp-pointed lava cone without crater(9 volcanoes; 2.0%), shield volcanoes(27 volcanoes; 5.9%), tuff rings(17 volcanoes; 3.7%), tuff cones(3 volcanoes; 0.7%), a maar(1 volcano; 0.2%) and lava domes(25 volcanoes; 5.5%). The monogenetic volcanoes include 15 small nested cinder cones(aloreum). The monogenetic volcanoes are more abundant in the eastern part of the island than in the western part. If the main cause of the weathering such as precipitation affected the shape of the monogenetic volcanoes, more monogenetic volcanoes(BC, CC, DC, etc.) are supposed to be present in the southern part that have more precipitation than in the northern part. But the distribution of the monogenetic volcanoes shows no difference between the southern and the northern parts. So we suggest that the difference of the climatic conditions did not affect the distribution or the shape of cinder cones. Tuff rings, tuff cones and a maar are distributed beneath the island or in the low-altitude areas along the shore although cinder cones are distributed in the interior of the island. This means that the volcanic activity which formed the monogenetic volcanoes resulted from either phreatomagmatic eruption or magmatic (hawaiian or strombolian) eruptions depending on the reaction with water (underground water or shallow waters). The distribution of the monogenetic volcanoes according to the altitude shows that 253(55.6%) volcanoes occur in low-lying coastal areas at an altitude below 300 m, 110(24.2%) in a middle mountainous area at an altitude between 300~600 m and 92(20.2%) in a high mountainous area at an altitude above 600 m. So more than half of monogenetic volcanoes are distributed in low-lying coastal areas.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.25 no.1
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• pp.37-49
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• 2012

A structural model of the SNF(spent nuclear fuel) disposal canister for the PWR(pressurized water reactor) for about 10,000 years long term deposition at a 500m deep granitic bedrock repository has been developed through various structural safety evaluations. The SNF disposal baskets of this canister model have the array type whose four square cross section baskets stand parallel to each other and symmetrically with respect to the center of the canister section. However, whether this developed structural model of the SNF disposal canister is optimal is not determinable yet. Especially, there is still a problem in weight-reduction of the canister. The cross section shape of the SNF basket should be changed to solve this problem. There are two ways in changing the cross section shape of the SNF basket; the one is to rotate the cross section itself and the other is to change the cross section shape as other shape different from the square cross section. The previous study shows that the canister with $30{\sim}35^{\circ}$ rotated basket array is structurally more stable than the canister with un-rotated parallel basket array. However, whether this canister with rotated basket array is optimal is not either determinable as yet, because it is not revealed that the canister with other cross section different from the square cross section is structurally more stable than other canisters. Therefore, the structural analysis of the SNF disposal canister with other cross section shape which is also symmetric with respect to the canister center planes is very necessary. The structural analysis of the canister with various cross section shape basket array in which each basket is arrayed symmetrically with respect to the center planes is carried out in this paper. The structural analysis result shows that the SNF disposal canister with circular cross section shape baskets located symmetrically with respect to the center of the canister section is structurally more stable than the previously developed SNF disposal canister with the parallel basket array.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.23 no.3
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• pp.289-301
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• 2010

A structural model of the SNF(spent nuclear fuel) disposal canister for the PWR(pressurized water reactor) for about 10,000 years long term deposition at a 500m deep granitic bedrock repository has been developed through various structural safety evaluations. The SNF disposal baskets of this canister model have the array type of which four square cross section baskets stand parallel to each other and symmetrically with respect to the center of the canister section. However whether this developed structural model of the SNF disposal canister is best is not determinable yet, because the SNF disposal canister with this parallel array has a limitation in shortening the diameter for the weight reduction due to the shortest distance between the outer corner of the square section and the outer shell. Therefore, the structural safety evaluation of the SNF disposal canister with the rotated basket array which is also symmetric with respect to the canister center planes is very necessary. Even though such a canister model has not been found as yet in the literature, the structural analysis of the canister with the rotated basket array for the PWR is required for the comparative study of the structural safety of canister models. Hence, the structural analysis of the canister with the rotated basket array in which each basket is rotated with a certain amount of degrees around the center of the basket itself and arrayed symmetrically with respect to the center planes is carried out in this paper. The structural analysis result shows that the SNF disposal canister with the rotated basket array in which the SNF disposal basket is rotated as 30~35 degrees around the center of the basket itself is structurally more stable than the previously developed SNF disposal canister with the parallel basket array.

• Fire Science and Engineering
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• v.17 no.1
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• pp.8-20
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• 2003

Natural gas has been supplied through underground pipelines and valve stations as a new city gas in Seoul. In contrast to its handiness the natural gas has very substantial hazards due to fires and explosions occurring from careless treatments or malfunctions of the transporting system. The main objectives of this study are to identify major hazards and to perform risk assessments after assessing reliabilities of the composing units in dealing with typical pipeline networks. there-fore two method, fault tree analysis ;1nd event tree analysis, are used here. Random valve stations are selected and considered its situation in location. The value of small leakage, large rupture, and no supply of liquefied natural gas is estimated as that of top event. By this calculation the values of small leakage are 3.29 in I)C valve station, 1.41 in DS valve station, those of large rup-lure are $1.90Times10_{-2}$ in DC valve station, $2.32$\times$10^{-2}$ in DS valve station, and those of no supply of LNG to civil gas company are $2.33$\times$10 ^{-2}$ , $2.89$\times$10^{-2}$ in each valve station. And through minimal cut set we can find the parts that is important and should be more important in overall system. In DC valve station one line must be added between basic event 26,27 because the potential hazard of these parts is the highest value. If it is added the failure rate of no supply of LNG is reduced to one fourth. In DS valve station the failure rate of basic event 4 is 92eye of no supply of LNG. Therefore if the portion of this part is reduced (one line added) the total failure rate can be decreased to one tenth. This analytical study on the risk assessment is very useful to prepare emergency actions or procedures in case of gas accidents around underground pipeline networks and to establish a resolute gas safety management system for loss prevention in Seoul metropolitan area.

• Journal of Korea Water Resources Association
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• v.46 no.12
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• pp.1193-1207
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• 2013

Increase of impervious area caused by overdevelopment has led to increase of runoff and then the problem of flooding and NPS were brought up. In addition, as decrease of base flow made groundwater level to decline, a stream that dries up is issued. low impact development (LID) method which is possible to mimic hydrological water cycle, minimize the effect of development, and improve water cycle structure is proposed as an alternative. As introduction of LID in domestic increases, the study on small watershed is in process mainly. Also, analysis of property of hydrological runoff and load on midsize watershed, like sewage treatment district, is required, the study on it is still insufficient. So, area applying LID practices from watershed of Dongrae stream is pinpointed and made the ratio and then expand it to watershed of Oncheon stream. Among low impact development practices, Green Roof, Porous Pavement, and Bio- retention are selected for the application considering domestic situations and simulated with SWMM-LID model of each watershed and improvement of water cycle and reduction of non-point pollution loads was analysed. Improvement of water cycle and reduction of non-point pollution loads were analyzed including the property of rainfall and soil over long term simulation. The model was executed according to scenario based on combination of LID as changing conductivity in accordance with soil type of the watershed. Also, this study evaluated area of LID application that meets the efficiency of conventional management as a criteria for area of LID practices applying to sewer treatment district by comparing the efficiency of LID application with that of conventional method.

• Journal of Korean Society of Forest Science
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• v.86 no.1
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• pp.69-79
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• 1997

The purpose of this study is to acquire essential data to reduce the amount of woody debris resulted from the debris flow. This research examined topographic characteristics of the channelbed affecting generation, movement and storage of woody debris and woody characteristics related to number, sizes, shapes, decay, storage direction to mountainous stream. 1. The number of woody debris had a tendency to increase in proportion to stream width, but it was hardly affected by longitudinal gradient of stream. Especially, the greater amount of woody debris was stored at wide section of the stream with compound channel, and it was found in deposits of channelbed rather than in the present channel. 2. Total woody debris over 10cm in diameter and over 2m in length was 402 units and storage number was 35.3 units per 100m of stream. Average diameter of breast height and length were 14cm and 4m, respectively. The woody debris appeared shorter in length and greater in diameter at down-stream than up-stream. 3. Since woody debris met sediments and bed-materials of great roughness in moving, the greater amount of woody debris without root was found in up-stream and down-stream, but deformed woody debris was discovered in upper stream. Decay of woody debris was more severe in down-stream and woody debris on rotting process was found down-stream. 4. Storage direction of woody debris was mainly parallel to center line of stream, and rate of parallel and perpendicularity was 276 and 126 units, respectively. But, as woody debris storing to the perpendicular direction was unstable, the traveling debris could easily be stored. Therefore, some counterplan was required to prevent the traveling woody debris. 5. Tree species of woody debris was mainly larch, which occupied about two third of total woody debris(256 units). The woody debris of larch is easy to move due to hitting of channelbed materials or lower channelbed fluctuation because the lower part of larch is weaker than its upper part. Therefore, the section of the tree species planting in the riparian vegetation needs much more carefulness.

• Journal of Korean Society of Forest Science
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• v.99 no.3
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• pp.323-330
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• 2010

This study was undertaken to compare early growth characteristics, such as height, diameter at root collar (DRC), and the dry weights of stem, branches, needles and roots between naturally regenerated and planted stands of Pinus densiflora for. erecta in Dae-gi and Bo-gwang site, Gangwon province, Republic of Korea. Average DRC growth was similar between the naturally regenerated and the planted stands in Dae-gi area, however, difference was statistically significant (P<0.01) between the naturally regenerated and the planted stands in Bo-gwang area, 4.66 cm and 2.61 cm, respectively. Average height of the naturally regenerated stands was significantly greater (P<0.01) than that of planted stands in both Dae-gi and Bo-gwang areas. The composition ratio of the dry weights for each part of measured trees was the highest in the stem in the naturally regenerated stands, but in the planted stands, the needle was the highest in both sites. The root/shoot ratio in the Dae-gi and Bo-gwang areas in the planted stands were much greater than those in the naturally regenerated stands, 0.25-0.30 and 0.17-0.18, respectively. The ratio of needle to stem biomass (N/S), branch to stem biomass (B/S), and needle to branch biomass (N/B) was significantly greater in the planted stands than those in the naturally regenerated stands in both sites. The results of this study represent that the regeneration methods, natural and artificial regenerations, can have an influence on the early growth of P densiflora for. erecta. This results not only provide the need for a correct planting method, but also will be useful in studies on the environmental adaptability of trees.

• Journal of agricultural medicine and community health
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• v.23 no.1
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• pp.65-78
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• 1998

This study was conducted to find out the factors which have an effect on the rural aged's natural history by disability in Activities of Daily Living(ADL) and ADL decline with 475 old people which were chosen except the dead 90 and unconfirmable 56 old people by performing follow-up survey for 4 years since 1993 on the basis of presurveyed data about 621 home old people over 60 years residing in 13 villages at Kangdong-myon, Kyongju-city, Kyongsangbuk-do Province, Korea. Such activities of daily living as bathing, dressing, going to toilet, transfer, feeding and continence were examined. 1. In the follow-up survey for 4 years, the ADL distribution of the dead was remarkably lower than the subject group. 2. It was also shown in the 4-year follow-up survey that 82.1% of high ADL group maintained high ADL while 77.8% of low ADL group died within 4 years. 3. The occurrence percentage of disabilities of each group by ADL item for 4 years appeared high in such an order as bathing, continence, dressing, going to toilet, transfer and feeding. 6.7%(8.1% for female and 4.6% for male) of the old people who were the high ADL group at the time of the first survey had disabilities that occurred after 4 years. 4. In the change of ADL according to general characteristics used to analyse the factors which have an effect on ADL decline, there was a significant difference in age and job, that is, the jobless old people had the higher degree of ADL decline. In the change of ADL according to behavioral pattern, for the male old people there was a significant difference in support of living expenses and subjective health condition. In this case, the degree of ADL decline was higher if they depended on their sons & daughters or spouses and felt that they were not healthy.

• Journal of the Korea Concrete Institute
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• v.24 no.3
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• pp.275-283
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• 2012

Steel Plate for Rebar Connection was recently developed to splice rebars in delayed slab-wall joints in high-rise building, slurry wall-slab joints, temporary openings, etc. It consists of several couplers and a thin steel plate with shear key. Cyclic loading tests on slab-wall joints were conducted to verify structural behavior of the joints having Steel Plate for Rebar Connection. For comparison, joints with Rebend Connection and without splices were also tested. The joints with Steel Plate for Rebar Connection showed typical flexural behavior in the sequence of tension re-bar yielding, sufficient flexural deformation, crushing of compression concrete, and compression rebar buckling. However, the joints with Rebend Connection had more bond cracks in slabs faces and spalling in side cover-concrete, even though elastic behavior of the joints was similar to that of the joints with Steel Plate for Re-bar Connection. Consequently, the joints with Rebend Connection had less strengths and deformation capacities than the joints with Steel Plate for Re-bar Connection. In addition, stiffness of the joints with Rebend Connection degraded more rapidly than the other joints as cyclic loads were applied. This may be caused by low elastic modulus of re-straightened rebars and restraightening of kinked bar. For two types of diameters (13mm and 16mm) and two types of grades (SD300 and SD400) of rebars, the joints with Steel Plate for Rebar Connection had higher strength than nominal strength calculated from actual material properties. On the contrary, strengths of the joints with Rebend Connection decreased as bar diameter increased and as grade becames higher. Therefore, Rebend Connection should be used with caution in design and construction.

• 한국지구과학회:학술대회논문집
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• 2010.04a
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• pp.108-109
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• 2010

IMPACT Silver 주식회사는 Zacualpan 프로젝트의 Royal Mines(이하 로얄 광산)을 인수했다. $124.5\;km^2$에 해당하는 지역의 소유권은 두 개의 멕시코 사기업으로부터 가행중인 광산의 채굴권 구입과 운영 중인 기반시설의 임대를 조건으로 한다. 프로젝트 지역은 멕시코시티로부터 남서방향으로 100 km와 Taxco Silver 광산으로부터 북서방향으로 25 km 떨어진 지점에 위치한다. 기반시설은 비포장 도로, 충분한 전력과 물의 공급 및 숙련공들을 갖추어 우수한 평가를 받고 있다. 소유권은 멕시코인의 개인소유 하에서 무한한 매장량 혹은 자원량을 갖고 운영된 채광과 가공시설을 인수하는 것이다. 소유권 지역을 대상으로 한 IMPACT Silver사의 주 탐사목적은 이미 알려진 광화대의 확장을 위한 잠재성 평가와 다른 지역에서 신규 광상의 유망지역을 발견하는 것이다. Zacualpan 프로젝트의 로얄 광산은 남동 Guerrero terrane의 북부에 위치한다. Teloloapan subterrane은 주로 저변성 녹색편암상으로 구성된 쥬라기 후기에서 백악기 초기의 화산성 퇴적층으로 구성된다. 대부분의 유망지역은 Lower Villa de Ayala층의 중성 내지 염기성 화산성 쇄설암을 모암으로 한다. 다상의 변성작용은 지역 전반에 걸쳐 나타나고, Zacualpan 광산지역에서 수반되는 광화작용을 규제한다. Zacualpan 광산지역은 Sierra Madre del Sur로 알려진 유망 광화대에 해당한다. 이 지역은 화산성 괴상 황화광상과 천열수 맥상광상이 우세하다. 대부분의 천열수 광화작용은 3.2-3.8억 년 전 마그마의 생성이 활발한 판구조 체제 동안 발생하였다. 역사적으로 가장 주요한 지역은 Lipton Vein이다. 현재 Zacualpan 지구에서 채광량은 은 200-500 g/t 정도로 보고되고 있다. 일부 지역은 고품위 은 광화작용(은 1,000 g/t 이상)을 수반하고 있으며, 이는 탐사의 주 타겟이 되고 있다. Zacualpan에서 은 광화작용은 은이 부화된 중유황 천열수 맥상광상으로 상당히 유명하다. Fresnillo, Pachuca 및 Taxco 광산을 포함한 멕시코 소유의 대규모의 잘 알려진 광산들이 이에 해당한다. 이러한 광산들은 부산물로서 금, 아연, 연이 생산된다. 이러한 광상들은 맥상과 각력상 및 산점상 또는 망상세맥의 형태로 산출된다. 광화작용은 석영과 탄산염 맥 내에 주로 황철석과 다양한 섬아연석, 방연석, 은 혹은 금 광물들을 수반한다. 경제성을 갖는 광화작용의 수직적인 연장은 평균적으로 대략 300 m이고, 멕시코 중부에 위치한 Fresnillo의 광화작용은 100 m에서 960 m의 연장을 갖는 것으로 알려져 있다. 아주 오랫동안 Zacualpan에서 광산관계자의 관측과 IMPACT Silver에서 최근 작업의 결과를 토대로, Zacualpan 광산지역의 탐사모델은 새로운 광상의 탐사를 위한 가이드로서 개발되었다. Zacualpan 광산지역에서 가장 높은 경제성을 갖는 광화작용은 북서와 남북방향의 맥 구조를 따라 수반된다. 이러한 맥 구조들은 종종 이 지역을 가로질러 수 km까지 추적되지만, 경제성을 갖는 광화작용은 맥 구조를 따라서 구조적으로 유리한 지역에서 부광대를 형성한다. 부광대를 형성하기 위한 가장 유리한 구조적 지역은 북서와 남북방향으로 발달한 맥 구조들이 교차하는 지역이다. 지난 30년간 채광된 주요 부광대는 폭이 2-6 m 이고 수평연장은 30-150 m 그리고 수직연장은 230-300 m에 이른다. 가장 높은 생산량을 보이는 부광대는 남북방향의 이차 맥들이 Guadalupe 광산의 Lipton 맥을 가로지르는 지역에서 발달한다. 남동쪽으로 현재 Compadres 광산의 Silver Shoot No. 1으로부터 고품위 은을 생산하는 지역은 북서방향의 San Agustin 맥이 북향의 Cometa Navideno 맥에 의해 절단되는 지역에서 산출한다. 모암은 광화작용을 규제하는 또 다른 중요한 요소이다. 광산지역에서 경제성을 갖는 모든 광화작용은 중성 내지 염기성 화산암 특히 안산암과 관련 모암에 배태된다. 부광대가 셰일 혹은 편암으로 전이되는 지역에서, 맥들은 소규모의 세맥으로 나뉘어 진다. Zacualpan의 전형적인 천열수 광상에서 부광대는 상부로 가면서 은의 함량이 증가하고, 하부로 가면서 연 아연의 함량이 증가하는 수직적 대상을 보인다. 금의 함량 변화는 보다 예측이 어려우나 상당히 중요하다. Zacualpan 광산지역의 탐사모델에 사용된 토양 채취, 정밀지도제작, 트렌치 및 시추탐광은 현재 IMPACT Silver사가 이 지역을 대상으로 한 가장 효율적인 탐사방법으로 입증되었다. Zacualpan 프로젝트의 로얄 광산은 하루 500 톤을 제련하는 기반시설과 수반된 채굴권을 갖는 가행 광산들을 포함한다. 현재 IMPACT Silver사는 두 곳의 타겟 지역에서 정밀지도제작, 토양 및 암석 채취, 12공 총 1866 m의 시추탐광에 의한 사전조사로 구성된 4 단계 탐사를 수행했다. 암석 1,953개, 토양 1,631 개, 389 개의 시추코어 시료가 채집되고 분석되었다. 이러한 작업은 추가탐사를 요구하는 수많은 유망 광화대를 규명했다. Compadres 광산에서 현재 가행중인 지하갱 시료는 레벨 1에서 0.9 m의 폭을 갖는 광체에서 은 680 g/t과 금 0.3 g/t, 레벨 3에서 1.67 m의 폭을 갖는 광체에서 은 12,591 g/t과 금 12.07 g/t의 품위를 갖는 것으로 나타났다. 레벨 1에서 3까지 2-3 m의 폭과 30-40 m 연장으로 채광되었다. 시추탐광은 고품위를 갖는 몇몇의 중첩된 맥을 발견했다. Compadres 광산에서 남동방향으로 200 m지점에 위치한 Soledad 지역에서 5 개의 시추공으로부터 동일 맥 시스템이 발견되었고, 고품위 부광대의 상부로 간주되는 몇몇 중요 지점이 발견되었다. 초기 단계의 탐사는 유망 시추탐광 지역인 중간정도 내지 고품위 유망 광화대를 규명했다.