• 한국수자원학회논문집
• /
• 제42권1호
• /
• pp.51-60
• /
• 2009

임진강유역은 유역의 2/3가 북한에 위치하고 있어 신뢰성 있는 강우 및 수문정보를 획득할 수 없었다는 점이 지금까지 홍수 피해를 가중시킨 요인 중의 하나로 지적되어 왔다. 본 연구에서는 상습적으로 홍수피해를 겪고 있는 임진강유역의 홍수피해를 경감하기 위한 노력의 일환으로서 임진강유역에 설치된 수문레이더를 활용하여 임진강 수계 전체에 대한 홍수유출을 모의하고자 하였다. 강우 및 최근 토양자료 등의 수문자료 확보가 곤란한 유역에 대하여 자체 개발한 분포형모형의 적용 가능성을 검토하였다. 수문곡선 결과 가용자료의 부족으로 인해 부분적으로 관측값과 불일치하는 경우도 있었지만, 첨두유량 및 전체적인 패턴은 비교적 양호한 결과를 보여줌으로써 실무적용가능성을 확인할 수 있었다.

• 자원리싸이클링
• /
• 제26권6호
• /
• pp.91-96
• /
• 2017

알칼리 용융법과 수 침출을 이용하여 탄화텅스텐(WC)으로부터 텅스텐(W) 회수에 관한 연구를 실시하였다. 알칼리 용융 처리는 알칼리염의 종류, 용융온도 및 용융시간을 변화시키면서 실시하였으며, 수 침출은 $25^{\circ}C$, 2시간 및 슬러리 농도 10 g/L로 고정하여 실시하였다. 알칼리염으로 질산나트륨($NaNO_3$)만 단독으로 사용한 경우, W의 수 침출율은 63.3%이었지만, 용융 첨가제인 수산화나트륨(NaOH) 혼합량이 증가할수록 침출율은 증가하였으며, 몰비 $WC:NaNO_3:NaOH=1:2:2$로 혼합한 용융물에서는 97.8%까지 증가하였다. NaOH는 용융 반응의 반응열 증가로 인한 반응 촉진제 역할을 한 것으로 판단된다.

• 한국환경교육학회지:환경교육
• /
• 제8권1호
• /
• pp.66-80
• /
• 1995

The purpose of this study was to investigate the housewives's recognition and practice on prevention of environmental pollution. The subjects of this study were 250 housewives, school students' mothers, living in Cheong-ju. Major findings were as follows: 1. In washing their faces and brushing their teeth, they saved the water very well, but in taking bath, washing the dished, using the water of the lavatory they did not save the water so well. 2. The kinds of the cleansers differed in taking a bath, washing the hair, and doing the laundry respectively : what they use most was hard soaps in taking bath, liquid cleansers mixed with shampoo and linse in washing the hair, and synthetic powder detergent in laundrying. They used more synthetic detergent than natural soaps, which is known to be a cause of water pollution. Especially, when they cleansed, they did not use a measuring cup. It resulted in the waste of detergent and accelerating of water pollution. Therefore, the environmental education for them was very urgently needed. 3. In handling domestic waste, the separate collection rate of empty bottles and old newspapers was very high, but that of used phone-call cards and used batteries was extremely low. It was truly nessesary to educate and step up publicic activities on the separate collection of phone-call cards and batteries caused environmental pollution. 4. The housewives had much knowledge about environmental pollution, but they did not practice it so well in their home. 5. The housewives made more effort than their children in preventing environmental pollution and saving resources. In conclusion, what is most important for solving environmental problem was for each citizen to make an effort to prevent environmental pollution, and the government's support and producing the atmosphere of the society for this was really needed.

• Forest Science and Technology
• /
• 제14권4호
• /
• pp.160-168
• /
• 2018

The seeds of Elaeocarpus serratus, a tropical underutilized fruit tree are characterized by hard seed coat and consequent poor water uptake and low germination. To improve the regeneration through seeds, various parameters such as viability of seeds, water uptake, and effect of seed mass on germination and pretreatments were performed using a completely randomized design (CRD). Tetrazolium (TZ) test was conducted using fresh, mature seeds revealed $50{\pm}2.56%$ mean viability. Seeds of different weight classes showed similar pattern of water uptake and the saturation level was achieved at 60 hrs of soaking. Seeds belong to weight class 2.6-3.5g were germinated ($12.5{\pm}1.26%$) with $175{\pm}1.75days$ (d) of mean time taken for germination (MTG). Germination capacity of seeds varied significantly among different populations and Varkala population gave $12.5{\pm}1.1%$ germination with $174.6{\pm}2.5d$ MTG. Among various seed treatments, mechanical scarification was superior in germination and significant reduction in MTG ($p{\leq}0.05$). The mechanical scarification by complete removal of seed coat resulted in $49.2{\pm}1.52%$ germination within a short period of time ($9.52{\pm}0.89d$ MTG). However, the complete removal of seed coat without damaging to embryo is a difficult task. An alternate treatment (Mechanical scarification II) by making cracks on nut faces vertically followed by soaking in distilled water for 24 hrs gave $48.4{\pm}1.73%$ germination with significantly reduced MTG ($12.14{\pm}0.56d$) over unsoaked, untreated control ($6.5{\pm}1.84%$ germination and $197.18{\pm}1.79d$ MTG; $p{\leq}0.05$). This treatment (Mechanical scarification II) is therefore recommended for E. serratus seeds as it can adopt easily and can achieve 7 fold increases in germination over control. The recorded germination through mechanical scarification is in tune with realized viability percentage of the seeds.

• 한국지반환경공학회 논문집
• /
• 제12권5호
• /
• pp.5-12
• /
• 2011

지반공학적으로 흙의 함수비는 흙의 역학적 거동특성을 예측할 수 있는 중요한 인자이다. 통례적으로 흙의 함수비는 $105^{\circ}C$ 건조로에서 16~24시간 동안 건조해 함수비 값을 구한다. 현재 이러한 방법은 가장 보편적인 방법이며 많은 실험 데이타가 축척되어 있으나, 동시에 현장에서 사용하기에는 많은 시간을 필요로 하고 문제 발생 시 신속한 대책마련이 어렵다는 단점이 있다. 최근 이러한 문제점을 보완하기 위해서 외국의 실험규정(ASTM, JGS)에서는 microwave oven을 이용한 함수비 측정법이 제정되어 있다. 또한 microwave oven에 의한 함수비의 신뢰성 평가에 관한 연구도 많이 이루어지고 있다. 본 연구에서는 주문진표준사, 카올리나이트, 벤토나이트, 화강풍화토, 유기토 등을 대상으로 microwave oven을 이용한 함수비 측정방법의 타당성을 확인했다. 신뢰성에 영향을 미치는 인자에 대해서 분석하고 신뢰성을 높이기 위한 방법에 대해서 고찰하였다.

• 원예과학기술지
• /
• 제31권1호
• /
• pp.117-122
• /
• 2013

본 실험은 경실 종자인 잇꽃의 종자구조와 발아특성을 밝히고자 수행하였다. 잇꽃 종자의 외형적 특징은 단단한 종피 표면에 제(hilum)와 주공(micropyle)이 있으며, 제는 종자의 발달과정에서 태좌와 연결되어 있었고, 주공은 암술대와 연결되어 있었던 부분이다. 종자 침종 후 2-3시간 후에 제의 표면이 열렸으며, 발아 시 유아(embryo)가 제를 뚫고 돌출되었다. 잇꽃 종자의 흡습 전에 제와 주공에 파라핀을 처리하여 밀봉한 결과, 제 부위를 밀봉한 처리에서 종자의 발아가 이루어지지 않아 잇꽃 종자의 수분과 산소 교환이 제를 통하여 이루어진다는 것을 확인하였다. 잇꽃 종자의 제가 물에 잠기도록 수분을 공급한 발아실험(top of paper method)에서는 $15^{\circ}C$에서 31.3%, $20^{\circ}C$에서 15.7%, 그리고 $25^{\circ}C$에서 6.0%가 발아하였으며, between-paper method에 의한 실험에서는 $15^{\circ}C$에서 45.5%, $20^{\circ}C$에서 30.0%, $25^{\circ}C$ 14.0%로 발아율이 나타났고, 토양에 파종한 종자는 온도에 관계 없이 80% 내외의 발아율을 보여, 잇꽃 종자의 발아에 수분공급 조건과 온도가 밀접하게 연관되어 있었다. 제(hilum)의 내부 구조를 SEM(scanning electron microscope)을 이용하여 관찰한 결과 도관요소를 구성하는 세포로 이루어져 있었다. 이러한 결과로 볼 때, 잇꽃 종자의 제(hilum)는 발아과정에서 수분흡수와 가스교환 통로가 되는 것으로 판단된다.

• Nuclear Engineering and Technology
• /
• 제53권8호
• /
• pp.2534-2546
• /
• 2021

Nuclear emergency preparedness and response is an essential part to ensure the safety of nuclear power plant (NPP). Key support technologies of nuclear emergency decision-making usually consist of accident diagnosis, source term estimation, accident consequence assessment, and protective action recommendation. Source term estimation is almost the most difficult part among them. For example, bad communication, incomplete information, as well as complicated accident scenario make it hard to determine the reactor status and estimate the source term timely in the Fukushima accident. Subsequently, it leads to the hard decision on how to take appropriate emergency response actions. Hence, this paper aims to develop a method for rapid source term estimation to support nuclear emergency decision making in pressurized water reactor NPP. The method aims to make our knowledge on NPP provide better support nuclear emergency. Firstly, this paper studies how to build a Bayesian network model for the NPP based on professional knowledge and engineering knowledge. This paper presents a method transforming the PRA model (event trees and fault trees) into a corresponding Bayesian network model. To solve the problem that some physical phenomena which are modeled as pivotal events in level 2 PRA, cannot find sensors associated directly with their occurrence, a weighted assignment approach based on expert assessment is proposed in this paper. Secondly, the monitoring data of NPP are provided to the Bayesian network model, the real-time status of pivotal events and initiating events can be determined based on the junction tree algorithm. Thirdly, since PRA knowledge can link the accident sequences to the possible release categories, the proposed method is capable to find the most likely release category for the candidate accidents scenarios, namely the source term. The probabilities of possible accident sequences and the source term are calculated. Finally, the prototype software is checked against several sets of accident scenario data which are generated by the simulator of AP1000-NPP, including large loss of coolant accident, loss of main feedwater, main steam line break, and steam generator tube rupture. The results show that the proposed method for rapid source term estimation under nuclear emergency decision making is promising.

• 헤리티지:역사와 과학
• /
• 제37권
• /
• pp.349-369
• /
• 2004

20세기에 들어와 컴퓨터의 발달로 문화재를 복원하는데 있어 다양한 자연과학적 방법이 시도되고 있다. 문화재에 적용되는 통계학을 비롯한 자연과학적인 방법을 통해 문화재의 재질에 대한 주성분 및 미량성분을 분석하여 산지추정을 할 수 있고, 더 나아가 고대의 교역 및 교류관계를 규명하고, 생산지와 소비지 사이의 정치 경제 문화관계 등 다양한 정보를 밝혀내고 있어 그 필요성이 더욱 요구되고 있다. 본 연구는 흡수율 및 광물결정분석, 편광현미경분석, 통계분석 등의 자연과학적인 방법을 이용하여 경기도 하남시 천왕사지 유적내 기와 가마로 추정되는 소성유구의 성격과 유구 및 주변 건물지에서 출토된 기와들에 대해 상호관계를 밝히고자 시도되었으며, 연구결과 다음과 같은 결론을 얻었다. 경질 기와 편들을 제외한 연질 기와 편들은 다른 기와에서 볼 수 있는 흡수율(10%이상)과 비슷한 수치를 보였으며, 흡수율이 낮은 일부시료에서는 Mullite, Tridymite, Cristobalite와 같은 고온 결정상 등이 존재하는 것으로 보아 다른 기와편에 비해 소성온도가 높았음을 알 수 있었다. 또한 미량성분을 통한 통계분석결과 소성유구와 천왕사지 내에서 출토된 기와는 한 군으로 분류된 것으로 보아, 밀접한 관련성을 가지고 있음을 알 수 있었고, 천왕사 축조시 원거리에서 기와를 공급받은 것이 아닌 사지 내에 가마를 설치한 후 공급하였음을 알 수 있었다.

• 한국지하수토양환경학회:학술대회논문집
• /
• 한국지하수토양환경학회 2002년도 총회 및 춘계학술발표회
• /
• pp.85-92
• /
• 2002

When the United Nation classified as Korea is the one of the water deficit country. The consensus was made that the water is the one of the precious national resources. Government increases their R/D budget trying to get more clean water bodies. For instances, 'Sustainable Water Resources Development' project is the one of major title in '21 Century Frontier Research project and there are several small research projects are undergoing by the Ministry of Agriculture and KARICO. However, when the environmental preservation issue has been get more emphasis, construction of the Surface Dam met the blockage from the environmentalists due to the problem of the their water buried area. Since the most fitting site for surface dam had been used in the past, some engineer move their focus on modification of the existing Dam's height to enlarge its capacity or dredging the bottom of the reservoir recently However dredging evoke water quality problem in return by accumulated materials at the bottom. Last year the Dong Gang Dam plan has been canceled by environmental problem in water buried area of the reservoir. With the point of this view, ground water gets more focus for the one of the useful alternative for clean water bodies. Underground dam technique which had widely applied once in the early nineteen eighties by the KARICO and attenuated due to engineering insufficiency. The technique is newly studied with the advanced engineering technique. Still groundwater usage rate in Korea is much lower comparing with the advanced countries and has many rooms to develop. Wells, under ground dam and radial collector wells are typical facilities up to now. There is little application in Korea for the Recharge Dam, which had been widely used in the advanced countries. The Recharge Dam is technique to conjunct surface water and groundwater body together, This technique had developed to increase groundwater recharge at the beginning This research is the result of the study on the possibility of the development of the new technology, Groundwater Reservoir' which was modified from Recharge Dam. Groundwater Reservoir is like a deep artificial lakes trenched in hard rock aquifer to get groundwater. The advantage of the Groundwater Reservoir is followings 1) It can be developed at the plains area, not in the deep valley 2) Huge water body can be developed without dam 3) Small buried area comparing surface water dam makes the least environmental effect. 4) Trenching cost can be substitute by the income of the selling rock debris 5) Outfit of the reservoir can be modified to match with the site prospect 6) Rock debris can be used as constructing materials 7) It can be used as groundwater recharge system when the heavy rains comes 8) The reservoir looks like scenery lake with huge clean water bodies.

• Water Engineering Research
• /
• 제1권1호
• /
• pp.83-92
• /
• 2000

Jet flow can occur by gate opening at downstream of a hydraulic structure such as weir of drainage gate. If the stream bed is not hard or the bed protection is not sufficient, vortex erosion occurs and a resulting scour hole will be formed due to the high shear stress of the jet flow. Once the scour hole is formed, a vortex occurs in ti and this vortex causes additional erosion. If this erosion continues and reaches to the hydraulic structure, it can undermine the bottom of the hydraulic structure and this will lead to failure of the structure itself. Thus, it is necessary to define the physical features of the vortex structure in the scour hole for the design of the bed protection. This study presents the turbulent vortex structure in the scour hole by the gate opening of the hydraulic structure. Characteristics of vortex motion, circulation, vortex scale and vortex were analyzed through experiments. Experimental results of the vortex velocity were compared with theoretical ones. From these, circulation and vortex scale were obtained with known values of inflow depth, inflow velocity and scale of scour hole