• Journal of Welding and Joining
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• v.4 no.3
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• pp.13-25
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• 1986

철강 구조물의 용접기술에 있어 용접부의 신속성을 좌우하는 가장 중요한 요소는 용접균열에 관한 문제와 용접본드부의 취화에 관한 문제로 요약될 수 있다. 일반적으로 용접부 및 그 근방의 금속은 국부적으로 매우 높은 온도까지 급열된 후 급냉되므로, 용접부에서 각종균열의 발성 위험성이 높아지고 용접본드부를 취화하여 파양인성의 저하를 초래하게 된다. 따라서 이러한 문 제점을 극복하기 위해서는 재료의 선택이나 설계, 시공, 검사의 각 단계에서 충분한 검토가 필 요하다. 특히 최근 들어 이전보다 높은 강도의 고장력강재가 널리 사용되고 구조물의 대형화에 따라 구속조건이 증대되며 구조물의 사용 조건은 더욱 가혹 화함에 따라 상술한 문제점은 더욱 중요시되고 있다. 철강 용접부에 발생하는 균열은 용접시공시 발생되는 균열과 용접완료후 구 조물 사용중에 발생되는 균열로 대별될 수 있다. 용접시공중 발생되는 균열은 용접열싸이클로 인해 생성되는 조직, 석출물등의 치금학적 요인과 잔유응력 또는 구속응력등의 역학적 요인이 중첩됨으로서 발생된다. 또한 사용중 발생되는 균열은 상기의 두 가지 요인이외에 환경적 요인이 첨가되어 발생된다고 볼 수 있다. 이상과 같은 용접균열을 방지하기 위해서는 실 구조물 용접 조립시의 각종 조건을 재현한 시험법을 통해 용접균열 발생의 한계조건을 정량적으로 분석할 필요가 있다. 이러한 균열 시험의 결과, 적정한 용접 시공 조건이 도출될 수 있기 때문이다. 이와 같은 필요성에 의해 지금까지 다수의 용접균열 시험법에 관한 연구가 행하여져 왔고 그 중에는 각 국가의 협회나 학회의 규격으로 확립된 것도 많으며 국제규격으로 되어 있는 것도 있다. 본 고에서는 각종균열들에 대한 지금까지 밝혀진 기구들에 대해 해설하고, 그 각각에 적용되고 있는 시험법들에 대해 소개하고저 한다.C1지구의 공업.생활용수는 103units, 33units로 배분되고, 하류지구에 304units로 배분되었다. 따라서 용도별로 물배분하므로서 금호강 하루지역에 더욱 많은 물을 배분할 수 있음을 알았다.통해서 수위-유량관계(rating curve)를 규명하였다. 시험지구의 관개효율 및 용수손실 규명 등에 관한 기본자료를 수집하기 위해서는 계측시스템의 운영은 장기간으로 지속 되어야 한다며, 전기전도도와 토양수 농도, 전기전도도와 함수량의 관계를 이용한 천이상태의 오염원 농도 측정방법을 개발하였다. 특히 제안식에서는 한계함수량의 개념을 도입하여 전기전도도와 함수량관계를 추정하므로 추정식의 실험값 반영 정도를 증가시켰다. 본 연구에서 제안된 식을 이용하여 추정된 전기전도도와 함수량관계는 다른 제안식에 비하여 개선된 결과를 보여 주었고, 본 연구에서 개발한 오염원 농도 측정법을 이용하여 측정한 결과 함수량이 0.15이하에서는 측정오차가 크지만 함수량이 0.15이상일 경우 매우 좋은 결과를 보였는데 질량평형을 검토한 결과 약 5-10%의 오차율을 보였다. 따라서 본 논문에서 개발된 천이상태의 오염원 농도측정법은 용존 오염물질의 이송에 관한 정확한 실험을 제공할 것으로 판단된다.며, 수질 보전적-환경 보전 차원에서 저수관리 체계를 확고히 할 수 있는 방안을 강구하여야 할 것이다.펄스주입법에 의해 증착된 박박은 강유전성 이력을 나타내었다.지역과 비도시지역을 비교하는 조사 연구가 필요하며, 이러한 조사결과를 바탕으로 자녀의 식습관에 대한 교육을 위한 교재, 교구의 개발과 영양, 식습관 교육프로그램의 개발을 통해 가정과 학교에서 부모와 교사가 자녀의 식생활 지도 관리를 돕고 가정과 교육기관이 연계한 교육 프로그램이 활성화 될 수 있도록 지속적인 관심을 기울여 나가야 할 것이며, 이에 따른

• Geophysics and Geophysical Exploration
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• v.21 no.1
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• pp.8-14
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• 2018

For the purpose of maintenance and prevention of earth fill dams against damage from natural hazards, automatic monitoring through various measuring instruments and resistivity survey has been carried out. Reservoirs and embankments have the structural vulnerability on the agricultural usages since most of them were built more than thirty years ago. The main aim to use monitoring method is to verify the safety and integrity of the dam. Resistivity survey can detect potential weaknesses, such as defective zones, anomalous seepages or internal erosion processes. Permanent resistivity monitoring systems were installed at a reservoir, which daily measurements have been taken every 6 hour. Using monitoring data for one year, anomalous seepage and structural defects were clarified for dam safety. Annual water level fluctuations are around 10 m. During their operation, reservoir dams are subject to a never-ending hydraulic load from the reservoir, which over the years may cause changes in the properties of the inner parts of the dam construction. Detailed analysis of the monitoring results was performed and showed that resistivities at most locations have been very stable over the full monitoring period excluding the effects of water fluctuation and seasons. To investigate the detectability of weak zone using the DC resistivity monitoring, numerical modeling with a simplified model for the drainage at a reservoir dam was also performed. The results showed that the seepage zone near drainage in a reservoir dam could be detected by resistivity response change.

• Magazine of the Korean Society of Agricultural Engineers
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• v.13 no.2
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• pp.2262-2275
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• 1971

Fourteenes rervoirs maintained by the local land improvement associations in the province of Chullabuk-Do and 20 reservoir maintained by thos in the province of Chullanam-Do, were surveyed in connection with a correction between storage capacity and sediment deposit. In addition to this survey, 3,347 of small reservoir, that lie scattered around in the above-mentioned two provinces were investigated by using existing two provinces were investigated by using existing records pertaining to storage capacity in the office of City and country, respectively. According to this investigation the following comclusions are derived. 1. A sediment deposition rate is high, being about $10.63m^3/ha$ of drainage area, and resulting in the average decreasc of storage capaity by 27.5%. This high rate of deposition coule be mainly attributed to the serve denudation of forests due to disorderly cuttings of trees. Easpecially, in small reservoir, an original average design storage depth of 197mm in irrigation water depth is decreased to about 140mm. 2. An average unit storage depth of 325.6mm as the time of initial construction is decreased to 226mm at present. This phenomena causes a greater shortage irrigation water, since it was assumed that original storage quantity was already in short. 3. Generally speaking, seepage rates through dam abutment intakepipe, etc, are high due to insufficient maintenance and management of reservoir. 4. It is recommended that sediment deposit should be dredged when a reservoir is dry in drought. 5. Farmers usually waste excessive irrigation water. 6. Water saving methods should be practiced by applying only necessary water for growing stage of rice. 7. In are as where water defficiency for irrigation is severe, a soil moisture content should be kept at about 70% by applying water once in several days. 8. Tube wells should be provided so as to exploit ground water and subsurface current below stream bed as much as possible. 9. If an intake weir was constructed, a water collection well should be built for the use in drought. 10. Water conservation should be forced by converting devastated forests contained in the drainage area of reservoir to protected forests so as to take priority of yrefor estation, gully control, the prohibition of disorderly cutting of trees, etc. 11. Collective rice nurseries should be adopted, and it should be recommended that irrigation water for rice nurseries is supplied by farmer themselves. 12. Sediment desposit in reservoir should be thoroughly dreged so as to secure a original design storage capacity. 13. The structure of overflow weir should be automatic so as to freely control flood level and not to increase dam height.

• Korean Journal of Agricultural Science
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• v.19 no.2
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• pp.201-237
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• 1992

본(本) 연구(硏究)는 1992년(年) 2월(月)부터 동년(同年) 8월(月)까지 한국(韓國)의 농어촌진흥공사(農漁村振興公社)(RDC)와 말레시아의 KTA기술용역단간(技術用役團間)의 기술제휴하(技術提携下)에 아세아개발은행(亞細亞開發銀行)의 기술협력기금(技術協力基金)에 의(依)한 말레지아북부(北部) Terengganu 농촌개발제(農村開發第)2단계사업(段階事業)의 타당성조사연구(妥當性調査硏究) 결과(結果) 중 말레시아정부(政府)의 경제정책방향(經濟政策方向), 농업개발(農業開發) 및 사업(事業)의 경제적(經濟的) 재무적(財務的) 타당성(妥當性)만을 발췌(拔萃)하여 본(本) 논문(論文)에 수록(收錄)하였다. 본(本) 농촌개발사업지구(農村開發事業地區)는 말레시아의 북동(北東)쪽에 위치(位置)하고 있는 Terengganu State의 Setiu-Besut양(兩) Distict가 포함(包含)되는데 경제적(經濟的)으로 가장 낙후(落後)된 지역(地域)으로 매년(每年) 행사(行事)처럼 찾아오는 홍수(洪水)때문에 농경지(農耕地)를 집약적(集約的)으로 경작(耕作)하지 못함으로써 지역농민(地域農民)들은 빈곤(貧困)에서 벗어나지 못하고 있고 침수기간중(浸水期間中)에는 지역(地域)의 경제활동(經濟活動)은 물론(勿論) 교통(交通)마저 불통(不通)되고 농촌하부구조(農村下部構造)의 손실(損失)은 물론(勿論) 사회경제적(社會經濟的)인 손실(損失)이 크며 Setiu River의 하구(河口)가 침전(沈澱)되어 어선(漁船)의 출입(出入)이 점점(漸漸) 곤란(困難)해지므로써 어민(漁民)들의 생계(生計)에도 위협(威脅)을 주는 지역(地域)이다. 따라서 본(本) 타당성(妥當性) 조사연구(調査硏究)의 근본적(根本的)인 목적(目的)은 농촌(農村)의 빈곤(貧困)을 타파(打破)하기 위하여 (1) 홍수(洪水)를 방지(防止)하고, 배수(排水) 및 관개개선(灌漑改善)을 하며, 하구(河口)를 개발(開發)하여 어민(漁民)들의 생산활동(生産活動)을 돕고 지역주민(地域住民) 및 농민(農民)들의 경제활동(經濟活動) 및 농업생산성(農業生産性)을 제고(提高)시키며 (2) 환경보호(環境保護) 및 관리(管理)를 통(通)하여 지역주민(地域住民)에게 쾌적(快適)한 농촌생활환경(農村生活環境)을 제공(提供)하고 생태계(生態系)의 변화(變化)를 방지(防止)하며 (3) 다각적(多角的)인 영농활동(榮農活動)을 통(通)하여 지역농민(地域農民)의 소득(所得)을 극대화(極大化) 할 수 있는 개발(開發)의 기본구상(基本構想)과 이에 대한 기술적(技術的) 경제적(經濟的) 타당성(妥當性)을 구명(究明)하는 것이다. 본(本) 사업지역(事業地域)의 총면적(總面積)은 9,500ha이며 이는 4,680ha의 기설지구(旣設地區)의 개보수관개사업(改補修灌漑事業)과 500ha의 과수단지(果樹團地), 200ha의 채소단지(菜蔬團地), 500ha의 옥수수단지(團地), 250ha의 엽연초생산단지(葉煙草生産團地), 2,760ha의 오일팜 및 고무나무단지에 소, 염소 및 양(洋)을 사육(飼育)하는 종합적(綜合的)인 농촌개발(農村開發)로서 농가(農家)의 농업소득제고(農業所得提高)에 큰 기여(寄與)를 하게 되며 Setiu강(江)의 유역(流域) 4,090ha에 대한 홍수경감대책(洪水輕減對策)으로 지역주민(地域住民)의 생활안정(生活安定) 및 교통(交通), 관광(觀光), 사회경제적(社會經濟的) 생산활동(生産活動)을 촉진(促進)하는 사업(事業)을 하게된다. 본(本) 사업(事業)의 공사기간(工事期間)은 1993년(年)부터 5개년간(個年間)이며 총사업비(總事業費)는 외화(外貨) 2천만불(千萬弗)을 포함(包含)하여 5천(千) 5백만불(百萬弗)로 추정(推定)되었다. 년간사업수익(年間事業收益)은 사업(事業)의 완전운영기간(完全運營期間)인 2003년(年)을 기준(基準)으로 할 때 15,541백만불(百萬弗)로 추정(推定)되었으며 사업(事業)의 내구기간(耐久期間)은 30년(年)으로서 2023년(年)까지 생산(生産)이 계속(繼續)될 것이다. 본(本) 사업(事業)의 전체재무수익율(全體財務收益率)은 22.49%이며 경제적(經濟的) 수익률(收益率)은 19.30%로 경제적(經濟的)인 타당성(妥當性)이 매우 높음을 알 수 있다. 모든 사업(事業)이 계획(計劃)대로 성공적(成功的)으로 추진(推進)될 경우 사업지역내(事業地域)의 몽리농가(蒙利農家) 4,000호(戶)가 큰 혜택(惠澤)을 보게되고 농촌(農村)의 빈곤수준(貧困水準)(Poverty Line)은 현재(現在)의 36%에서 18%수준(水準)으로 경감(輕減)될 것이 기대(期待)되고 있다.

• Economic and Environmental Geology
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• v.55 no.2
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• pp.209-217
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• 2022

The purpose of this study was to confirm the dissolution of arsenic from the stabilized soil around abandoned coal mines by cultivation activities. Experimental soils were collected from the agricultural field around Okdong and Buguk coal mines, and the concentration of arsenic in the soil and the geochemical mobility were confirmed. The average arsenic concentration was 20 mg/kg. The soil with relatively high geochemical mobility of arsenic in the soil was used in the batch and column experiment. The limestone was mixed with soil for soil stabilization, and the mixing ratio was 3% of limestone, based on the soil weight. The phosphoric acid fertilizer (NH₄H₂PO₄) was added to the soil to simulate a cultivation condition according to the Rural Development Administration's rules. Comparative soil without mixing limestone was prepared and used as a control group. The arsenic extraction from soil was increased following the fertilizer mixing amount and it shows a positive relationship. The concentration of phosphate in the supernatant was relatively low under the condition of mixing limestone, which is determined to be result of binding precipitation of phosphate ions and calcium ions dissolved in limestone. Columns were set to mix phosphoric acid fertilizers and limestone corresponding to cultivation and stabilization conditions, and then the column test was conducted. The variations of arsenic extraction from the soil indicated that the stabilization was effectible until 10 P.V.; however, the stabilization effect of limestone decreased with time. Moreover, the geochemical mobility of arsenic has transformed by increasing the mobile fractions in soil compared to initial soil. Therefore, based on the arsenic extraction results, the cultivation activities using phosphoric fertilizer could induce a decrease in the stabilization effect.

• Korean Journal of Soil Science and Fertilizer
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• v.28 no.2
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• pp.165-175
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• 1995

To determine the effect of soil moisture stress on growth of barley and grain quality, a pot experiment was carried out for two barley varieties(Olbori and Chogangbori) by using large plastic pot(52cm in diameter and 55cm in depth) filled with sandy loam soil under rain-controlled open green house. By means of measuring soil water potential with micro tensiometer and gypsum block installed at 10cm in soil depth, soil moisture was controlled by sub-irrigation at several irigation points such as -0.05bar, -0.2bar, -0.5bar, -1.0bar, -5.0bar and -10.0bar in soil water potential. The lower soil water potential was controlled, the shorter length of stem and internode became, and the more narrow stem diameter was. Leaf area was significantly decreased when soil water potential was controlled lower than -0.5bar, although chlorophyll content of flag and first leaves was not changed so much. Weight of grain and ear was significantly decreased when soil water potential was lower than -5.0bar and the highest grain yield was obtaind in a plot where soil water potential was controlled at -0.2bar. However, the most efficient water use of Olbori and Chogangbori was obtained at -0.5bar and -1.0bar in water potentials, respectively. Crude protain content, maximum viscosity, consistency and ${\beta}$-glucan content of barley flour increased as soil water potential significantly decreased, especially below -5.0bar, but gelatination temperature decreased as soil water potential decreased.

• Korean Journal of Weed Science
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• v.17 no.1
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• pp.10-23
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• 1997

This study was carried out to determine distribution and tuberization characteristics of tubers of water chestnut(Eleocharis Kuroguwai Ohwi) which is a dominant weed species and diffult to control during 1993 to 1994. By early planting of E. kuroguwai tubers, more and heavier tubers were developed, but the tubers were tended to distribute at the upper soils. Large proportion of tubers was remained at the upper 0 to 10cm soil layer and a few tubers were formed below 20cm. Tubers developed earlier tended to be at deeper layer, while later developed tubers were at upper layers. Tuber weight was increased from the surface to 20cm soil depths, but that formed below 20cm was almost same. No tillage resulted in more tuber formation which were distributed at upper soil layers when compared to conventional tillage. Cool water irrigation pumped from ground water resulted in less tuberization but smaller tubers when compared to control. Shading with color cellophan films resulted in smaller tuber formation with lower in sprouting percentage. Among the films tested, the most significant effect was obtained with green color.

• Korean Journal of Soil Science and Fertilizer
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• v.38 no.3
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• pp.150-156
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• 2005

The increasing emission of greenhouse gases may change agricultural environment. The agronomic productivity will depend upon change of temperature, precipitation, solar radiation and fertilization. This study was conducted to investigate greenhouse gas emission with irrigation water depth in paddy field. Area of each experiment plot is $70m^2$, Three treatments with three replications were carried out in this experiment, which was laid out as randomized complete block design. The treatments of irrigation water were maximum field water capacity and 4 and 8 cm depth. The application rate of fresh rice straw was $8,000kg\;ha^{-1}$ in combination with chemical fertilizers ($110kg\;N\;ha^{-1}$, $45kg\;P_2O_5\;ha^{-1}$ and $57kg\;K_2O\;ha^{-1}$). The $CH_4$ emission was highest at 32 days after rice transplanting with rice straw treatment. The $CH_4$ emission in the plot of maximum field water capacity was lower compared with 4 and 8 cm of irrigation depth. $CH_4$ and $N_2O$ emission under different water depth in the paddy field were 30 and $1.52kg\;ha^{-1}$ at 8 cm depth, 281 and $1.71kg\;ha^{-1}$ at 4 cm depth, and 219 and $2.01kg\;ha^{-1}$ at water saturated condition. The total emission of greenhouse gases equivalent to $CO_2$ emission with rice straw application were $6,939kg\;CO_2\;ha^{-1}$ at 8 cm depth plot, $6,431kg\;CO_2\;ha^{-1}$ at 4 cm depth plot and $5,222kg\;CO_2\;ha^{-1}$ at water saturated condition. The GWPs without rice straw application were $4,449kg\;CO_2\;ha^{-1}$ at 8 cm depth plot, $3,702kg\;CO_2\;ha^{-1}$ at 4 cm depth plot and $4,579kg\;CO_2\;ha^{-1}$ at water saturated condition.