• The Journal of Engineering Geology
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• v.20 no.1
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• pp.79-87
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• 2010

Field water qualities (temperature, pH, Eh, EC, DO) was monitored by 6 times March to September 2009 on background water (BW) and acid mine drainage (AMD0, AMD1, AMD2 and AMD3 points), and flow rate was measured on AMD0 point. Acid mine drainage flowed out from abandoned Ilgwang mine were high acid waters that lower than pH 3, and Eh component was ranged 400 to 600 mV. EC measured on acid mine drainage were higher over 10 times than background water, DO component was increased by reaction on the air during the water flow from AMD0 point to AMD4 point. Heavy metal concentrations in acid mine drainage were ordered Fe > Cu > Zn > Mn > As > Cd, and Fe concentration was highest for 81.870~474.30 mg/L. Monitoring periods measured maximum concentrations of heavy metals were May for As and Cd, June for Fe, July for Cu, Zn and Mn. The periods measured minimum concentrations were monitored April for Cd and Mn, September for Fe, Cu, Zn and As. Discharge mass of heavy metal components were calculated 53.44 kg for Fe, 6.25 kg for Cu, 5.26 kg for Zn, 2.13 kg for Mn, 0.14 kg for As and 0.04 kg for Cd, respectively. Total discharge mass of heavy metal components were calculated 67.26 kg for 1 day, and Fe component was taken 79% of total mass.

• Proceedings of the Korea Water Resources Association Conference
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• 2015.05a
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• pp.519-519
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• 2015

2007년 발간된 IPCC의 4차 평가보고서에서 자연재해, 환경, 해양, 농업, 생태계, 보건 등 다양한 부분에 미치는 기후변화의 영향에 대한 과학적 근거들이 제시되면서 기후변화는 현세기 범지구적인 화두로 대두되고 있다. 또한, 기후변화에 의한 지구 온난화는 대규모의 수문순환 과정에서의 변화들과 연관되어 담수자원은 기후변화에 대단히 취약하며 미래로 갈수록 악영향을 받을 것으로 6차 기술보고서에서 제시하고 있다. 특히 우리나라는 지구온난화가 전 지구적인 평균보다 급속하게 진행될 가능성이 높기 때문에 기후변화에 대한 담수자원 취약성이 더욱 클 것으로 예상된다. 따라서 지표수에 용수의존도가 높은 우리나라의 댐 저수지를 대상으로 기후변화에 따른 수환경 변화의 정확한 분석과 취약성 평가는 필수적이다. 본 연구에서는 SRES A1B 시나리오를 적용하여 기후변화가 주암호 저수지의 수환경 변화에 미치는 영향을 분석하였다. 지역스케일의 미래 기후시나리오 생산을 위해 인공신경망(Artificial Neural Network.,ANN)기법을 적용하여 예측인자(강우, 상대습도, 최고온도, 최저온도)에 대해 강우-유출모형에 적용이 가능한 지역스케일로 통계적 상세화를 수행하였으며, 이를 유역모델에 적용하여 저수지 유입부의 유출량 및 부하량을 예측하였다. 유역 모델의 결과를 토대로 저수지 운영모델에 저수지 유입부의 유출량을 적용하여 미래 기간의 방류량을 산정하였으며, 최종적으로 저수지 모델에 유입량, 유입부하량 및 방류량을 적용하여 저수지 내 오염 및 영양물질 순환 및 분포 예측을 통해서 기후변화가 저수지 수환경에 미치는 영향을 평가하였다. 기후변화 시나리오에 따른 상세기 후전망을 위해서 기후인자의 미래분석 기간은 (I)단계 구간(2011~2040년), (II)단계 구간(2041~2070년), (III) 단계 구간(2071~2100년)의 3개 구간으로 설정하여 수행하였으며, Baseline인 1991~2010년까지의 실측값과 모의 값을 비교하여 검증하였다. 강우량의 경우 Baseline 대비 미래로 갈수록 증가하는 것으로 전망되었으며, 2011년 대비 2100년에서 연강수량 6.4% 증가한 반면, 일최대강수량이 7.0% 증가하는 것으로 나타나 미래로 갈수록 집중호우의 발생가능성이 커질 것으로 예측되었다. 유역의 수문 수질변화 전망도 강수량 증가의 영향으로 주암댐으로 유입하는 총 유량이 Baseline 대비 증가 하였으며, 유사량 및 오염부하량도 증가하는 것으로 나타났다. 저수지 수환경 변화 예측결과 유입량이 증가함에 따라서 연평균 체류시간이 감소하였으며, 기온 및 유입수온 상승의 영향으로 (I)단계 구간대비 미래로 갈수록 상층 및 심층의 수온이 상승하는 것으로 나타났다. 연중 수온성층기간 역시 증가하는 것으로 나타났으며, 남조류는 (I)단계 구간 대비 (III)단계 구간으로 갈수록 출현시기가 빨라지며 농도 역시 증가하였다. 또한 풍수년, 평수년에 비해 갈수년에 남조류의 연평균농도 상승폭과 최고농도가 크게 나타나 미래로 갈수록 댐 유입량이 적은 해에 남조류로 인한 피해 발생 가능성이 높아질 것으로 예상된다.

• Proceedings of the Korea Water Resources Association Conference
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• 2018.05a
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• pp.367-367
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• 2018

전 세계적으로 이상기후에 의한 영향으로 여름철 장마와 같은 우기가 점차 사라지고 집중호우 및 가뭄이 빈번하게 발생하는 등 지하수위 변동성에 따른 물 부족 현상이 발생하고 있다. 특히, 제주특별자치도는 하천수 및 저수지의 수원을 농업용수로 이용하는 내륙지역과는 달리 농업용수의 수원으로 지하수를 이용하고 있어 향후 기후변화로 인한 극단적인 가뭄과 농업형태의 변화등 지하수의 의존도는 가속화 될 전망이다. 따라서, 제주특별자치도는 지하수 관리차원에서 신규관정개발을 최소화 하고 용수공급량의 부족과 불균형을 해소시키기 위하여 2016년부터 농업용수 광역화 사업을 추진하고 있다. 본 연구는 제주특별자치도에서 추진하고 있는 '농업용수 광역화 사업'과 연계하여 용천수를 활용한 농업용 수자원 확보를 위하여 용천수 및 상시하천수의 정량적인 수량파악 및 농업용 수질기준에 적절한 유출수를 선정하고 제주지역 농업용수에 대체수자원을 활용한 지하수 의존비율을 저감시키는데 목표를 두고 수행되었다. 제주특별자치도 서귀포 지역에 분포하고 있는 16개 용천수 및 2개 상시하천을 대상으로 최종 해안으로 유출되는 10개 지점에서 농업용수 활용가능성을 검토한 결과 최소 유량 값은 각 지점별로 속골물 6,313.3($m^3$/일), 조이통물 11,406.3($m^3/day$), 꿩망물 8,402.8($m^3/day$), 선궷내물 4,290.8($m^3/day$), 논짓물 690.8($m^3/day$), 대왕수 1063.0($m^3/day$), 작지물 7,060.4($m^3/day$), 하강물 1,487.6($m^3/day$), 악근천 1,043.6($m^3/day$), 예래천 2,114.4($m^3/day$)로 산정되었으며, 수질 분석에 있어서는 작지물을 제외한 9개 지점에서 농업용수 사용 기준을 충족 하였다. 이상의 결과는 향후 제주특별자치도의 농업용수 공급량의 부족과 불균형 해소 및 지하수 관리차원의 신규관정 개발을 최소화 하는데 보탬이 될 것으로 판단된다.

• Proceedings of the Korea Water Resources Association Conference
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• 2020.06a
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• pp.206-206
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• 2020

토지이용의 고도화에 따라 비점오염원 부하는 증가하는 추세이며 기후변화에 따른 강우강도 증가 등으로 지표면에 축적된 고농도의 비점오염물질이 하천으로 유출, 수질오염을 가중시키고 있어 비점오염원 관리가 필요하다. 환경부에서 효율적인 비점오염원 관리를 위하여 2004년부터 현재까지 3단계에 걸쳐 비점오염원 관리 종합대책을 수행하고 있으며, 2008년부터 비점국고보조사업을 추진하여 비점오염저감시설 설치를 통한 수질개선 및 수생태계 건강성 확보에 기여하고자 하였다. 이에 본 연구는 비점국고보고사업을 통해 구축된 비점오염저감시설을 대상으로 시설 설치 및 운영 현황과 강우시 비점오염저감 효과 분석을 통한 시설의 평가를 수행하고자 한다. 연구대상시설은 시범시설 및 국고보조시설 총 70개소로 2005~2017년에 준공되었으며, 2016년부터 현재까지 총 4년동안 진행된 모니터링을 바탕으로 연구를 수행하였다. 시설의 용량은 34~97,000㎥의 범위로 SA/CA 1.2~6.6%의 범위이다. 강우시 모니터링은 선행무강우일수 3일이상을 고려하여 수행하였으며 도시지역의 경우 5mm 이상, 농촌지역 10mm 이상시 모니터링을 진행하였다. 시설의 유입과 유출부에서 수질 및 유량 모니터링을 진행하였으며, 수질오염공정시험법에 준하여 BOD, COD, SS, T-N 및 T-P 항목에 대해 분석을 수행하였다. 모니터링 결과, 국내 비점오염저감시설의 평균 부하량은 SS 250.4 kg/day, BOD 89.2 kg/day, COD 136.2 kg/day, TN 51.4 kg/day, TP 7.1 kg/day 로 분석되었으며, 유출부 의 경우 SS 83.8 kg/day, BOD 37.2 kg/day, COD 51.0 kg/day, TN 15.4 kg/day, TP 2.0 kg/day로 나타났다. 또한, 은 오염물질 유입 및 유출 부하량의 상관관계 분석결과 SS, BOD, COD의 유입 및 유출 부하량의 상관성은 높게 나타났으며 특히 유기물질(BOD, COD)의 상관성은 0.8이상으로 분석되었다(p<0.005). 이는 비점오염저감시설에 적용된 식생, 미생물, 여재 등을 통하여 물리학적 및 생태학적 처리를 통해 저감되기 때문으로 판단된다. 하지만, TN은 인위적 요인과 자연적 요인이 복합적으로 작용으로 배출 특성으로 상관성은 매우 낮은 것으로 분석되었다.

• Journal of Fisheries and Marine Sciences Education
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• v.10 no.1
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• pp.15-30
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• 1998

The variation of the catches of Skipjack(Euthynnus pelamis) and the relationships between the SST and the fishing ground is examined using the catches data of skipjack obtained by Iwawada Fisheries Cooperative of Chiba Prefecture in Japan from 1982 to 1988. The annual mean catch for Skipjack was 151,375.1kg. the annual fluctuation of catch was that the catch in 1984 was increasing, but it was decreased less than 50% in 1985, and was repeated after being a little recovered in 1986, and it was recovered with the level of 1984 in 1988. The fluctuation of catch for Skipjack in every fishing term is that daily mean catch of the primary fishing term (January, February and March) is 894.6kg, but the middle fishing term(April and May) more than four times of the primary fishing term is 3,666.0kg, the last fishing term(June and July) was decreasing at 767.9kg and the fishing ground gradually becomes extinct. The annual mean SST in fishing ground was an extent of from $19.0^{\circ}C$ to $20.2^{\circ}C$, the mean SST of every year except 1983 was from $19.0^{\circ}C$ to $19.9^{\circ}C$. It is said that the optimum SST of Skipjack in Sotobo sea area is the degree of $19.0^{\circ}C$. Therfore, the thing which will guess the time and the location appeared the optimum SST is the very important factor to operate efficiently. About the extent of SST in fishing ground, it was from $17.0^{\circ}C$ to $19.0^{\circ}C$ on March, from $17.5^{\circ}C$ to $20.5^{\circ}C$ on April and from $17.5^{\circ}C$ to $23.5^{\circ}C$ on May, which the extent of SST was gradually larger and larger, on June from $21.0^{\circ}C$ to $23.5^{\circ}C$, fishing ground was formed only the degree of SST more than $21.0^{\circ}C$.

• Journal of Korean Society of Forest Science
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• v.82 no.2
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• pp.152-165
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• 1993

This is the basic study in order to know the amount of transpirational water loss in a Larix leptorepis stand by a heat pulse method. Especially this study has been measured and discussed the diurnal and seasonal trends of heat pulse velocity by changes of radiation, temperature and humidity, differences of heat pulse velocity by direction and depth in stem, differences of heat pulse velocity by dominant, codominant and suppressed trees, diurnal change of heat pulse velocity by change of leaf water potential, sap flow path way in sapwood by dye penetration and amount of daily and annual transpiration in a tree and stand. The results obtained as follows : 1. Relation between heat pulse velocity(V) and sap flow rate(SFR) was established as a equation of SFR=1.37V($r=0.96^{**}$). 2. The sap flow rate presented in the order of dominant, codominant and suppressed tree, respectively. The daily heat pulse velocity was changed by radiation, temperature and vapor pressure deficit. 3. The heat pulse velocity in individual trees did not differ in early morning and in late night, but had some differed from 12 to 16 hours when radiation was relatively high. 4. The heat pulse velocity and leaf water potential showed similar diurnal variation. 5. The seasonal variation of heat pulse velocity was highest in August, but lowest in October and similar value of heat pulse velocity in the other months. 6. The heat pulse velocity in stem by direction was highest in eastern, but lowest in southern and similar velocity in western and northern. 7. The difference of heat pulse velocity in according to depths was highest in 2.0cm depth, medium in 1.0cm depth, and lowest in 3.0cm depth from surface of stem. 8. The sap flow path way in stem showed spiral ascent turning right pattern in five sample trees, especially showed little spiral ascent turning right in lower part than 3m hight above ground, but very speedy in higher than 3m hight. 9. The amount of sap flow(SF) was presented as a equation of SF=1.37AV and especially SF in dominant tree was larger than in codominant or suppressed tree. 10. The amount of daily transpiration was 30.8ton/ha/day and its composition ratio was 83% at day and 17% at night. 11. The amount of stand transpiration per month was largest in August(1,194ton/ha/month), lowest in May (386ton/ha/month). The amount of stand transpiration per year was 3,983ton/ha/year.

• Korean Journal of Food Science and Technology
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• v.37 no.3
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• pp.438-442
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• 2005

Granule swelling is essential phenomenon of starch gelatinization in excess water, and characteristic of heated starch dispersion depends largely on size and distribution of swelled starch granule. Although swelling characteristic of starch granules depends on type of starch, heating rate, and moisture content, influence of heating rate on swelling phenomenon of starch granule has not been fully discussed, because constant heating rate of starch dispersion cannot be obtained by conventional heating method. Ohmic heating, electric-resistant heat generation method, applies alternative current to food materials, through which heating rate can be easily controlled precisely and conveniently at wide range of constant heating rates. Starch dispersion heated at low heating rates below $7.5^{\circ}C/min$ showed Newtonian fluid behavior, whereas showed pseudoplastic behavior at heating rates above $16.4^{\circ}C/min$. Apparent viscosity of starch dispersion increased linearly with increasing heating rate, and yield stress was dramatically increased at heating rates above $16.4^{\circ}C/min$. Average diameter of corn starch granules during ohmic heating was dramatically increased from $30.97\;to\;37.88\;{\mu}m$ by increasing heating rate from $0.6\;to\;16.4^{\circ}C/min$ (raw corn starch: $13.7\;{\mu}m$). Hardness of starch gel prepared with 15% corn starch dispersion after heating to $90^{\circ}C$ at different heating rates decreased gradually with increasing heating rate, then showed nearly constant value from $9.4\;to\;23.2^{\circ}C/min$. Hardness increased with increase of heating rate higher than $23.2^{\circ}C/min$.

• Journal of Animal Environmental Science
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• v.17 no.1
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• pp.39-48
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• 2011

The present survey was conducted to provide basic information on automatic milking system (AMS) in relation to purchase motive, milk yield and quality, customer satisfaction, difficulties of operation and customer suggestions, etc. Purchase motives of AMS were insufficient labor (44%), planning of dairy experience farm (25%), better performance of high yield cows (19%) and others (6%), respectively. Average cow performance after using AMS was 30.9l/d for milk yield, 3.9% for milk fat, 9,100/ml for bacterial counts. Sixty-eight percentage of respondents were very positive in response to AMS use for their successors but 18% were negative. The AMS operators were owner (44%), successor (44%), wife (6%) and company worker (6%), respectively. The most difficulty (31%) in using AMS was operating the system and complicated program manual. The rate of response to system error and breakdown was 25%. The reasons for culling cow after using AMS were mastitis (28%), reproduction failure (19%), incorrect teat placement (12%), metabolic disease (7%) and others (14%), respectively. Fifty-six percentages of the respondents made AMS maintenance contract and 44% did not. Average annual cost of the maintenance contract was 6,580,000 won. Average score for AMS satisfaction measurement (1 to 5 range) was 3.2 with decrease of labor cost 3.7, company A/S 3.6, increase of milk yield 3.2 and decrease of somatic cell count 2.8, respectively. Suggestions for the higher efficiency in using AMS were selecting cows with correct udder shape and teat placement, proper environment, capital and land, and attitude for continuous observation. Systematic consulting was highly required for AMS companies followed by low cost for AMS setup and systematization of A/S.

• Journal of Korea Water Resources Association
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• v.41 no.12
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• pp.1219-1230
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• 2008

Stream inflows induced by flood runoffs have a higher density than the ambient reservoir water because of a lower water temperature and elevated suspended sediment(SS) concentration. As the propagation of density currents that formed by density difference between inflow and ambient water affects reservoir water quality and ecosystem, an understanding of reservoir density current is essential for an optimization of filed monitoring, analysis and forecast of SS and nutrient transport, and their proper management and control. This study was aimed to quantify the characteristics of inflow density current including plunge depth($d_p$) and distance($X_p$), separation depth($d_s$), interflow thickness($h_i$), arrival time to dam($t_a$), reduction ratio(${\beta}$) of SS contained stream inflow for different flood magnitude in Daecheong Reservoir with a validated two-dimensional(2D) numerical model. 10 different flood scenarios corresponding to inflow densimetric Froude number($Fr_i$) range from 0.920 to 9.205 were set up based on the hydrograph obtained from June 13 to July 3, 2004. A fully developed stratification condition was assumed as an initial water temperature profile. Higher $Fr_i$(inertia-to-buoyancy ratio) resulted in a greater $d_p,\;X_p,\;d_s,\;h_i$, and faster propagation of interflow, while the effect of reservoir geometry on these characteristics was significant. The Hebbert equation that estimates $d_p$ assuming steady-state flow condition with triangular cross section substantially over-estimated the $d_p$ because it does not consider the spatial variation of reservoir geometry and water surface changes during flood events. The ${\beta}$ values between inflow and dam sites were decreased as $Fr_i$ increased, but reversed after $Fr_i$>9.0 because of turbulent mixing effect. The results provides a practical and effective prediction measures for reservoir operators to first capture the behavior of turbidity inflow.

• Magazine of the Korean Society of Agricultural Engineers
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• v.13 no.1
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• pp.2206-2217
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• 1971

Spillway and discharge channel of reservoirs require the Control of Large volume of water under high pressure. The energies at the downstream end of spillway or discharge channel are tremendous. Therefore, Some means of expending the energy of the high-velocity flow is required to prevent scour of the riverbed, minimize erosion, and prevent undermining structures or dam it self. This may be accomplished by Constructing an energy dissipator at the downstream end of spillway or discharge channel disigned to dissipated the excessive energy and establish safe flow Condition in the outlet channel. There are many types of energy dissipators, stilling basins are the most familar energy dissipator. In the stilling basin, most energies are dissipated by hydraulic jump. stilling basins have some length to cover hydraulic jump length. So stilling basins require much concrete works and high construction cost. Flip bucket type energy dissipators require less construction cost. If the streambed is composed of firm rock and it is certain that the scour will not progress upstream to the extent that the safety of the structure might be endangered, flip backet type energy dissipators are the most recommendable one. Following items are tested and studied with bucket radius, $R=7h_2$,(medium of $4h_2{\geqq}R{\geqq}10h_2$). 1. Allowable upstream channel slop of bucket. 2. Adequate bucket lip angle for good performance of flip bucket. Also followings are reviwed. 1. Scour by jet flow. 2. Negative pressure distribution and air movement below nappe flow. From the test and study, following results were obtained. 1. Upstream channel slope of bucket (S=H/L) should be 0.25<H/L<0.75 for good performance of flip bucket. 2. Adequated lip angle $30^{\circ}{\sim}40^{\circ}$ are more reliable than $20^{\circ}{\sim}30^{\circ}$ for the safety of structures.