• Title/Summary/Keyword: Variation Part

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A Numerical Study on the Wintertime Upwind flow of the Yellow Sen in an Idealized Basin

  • Kyung, Tae-Jung;Park, Chang-Wook;Oh, Im-Sang;Lee, Ho-Jin;Kang, Hyoun-Woo
    • Journal of the korean society of oceanography
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    • v.37 no.3
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    • pp.91-107
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    • 2002
  • The wintertime upwind flow in the Yellow Sea has been investigated through a series of two-dimensional numerical experiments in an idealized basin. A total of 10 experiments have been carried out to examine the effects of wind forcing, bottom friction and the presence of oceanic currents sweeping the shelf of the East China Sea. A spatially uniform steady and periodic wind stresses are considered along with comparison of linear and quadratic formulations. The wind-driven flow in the absence of oceanic current has been computed using Proudman open boundary condition (POBC), while the wind-driven current in the presence of oceanic current has been computed using Flather’s radiation condition (FOBC). The oceanic currents to be prescribed at the open boundary have been simulated by specifying uniform sea level gradients across the Taiwan Strait and the eastern ECS shelf, Calculations show that, as seen in Lee et al. (2000), oceanic flow little penetrates into the Yellow Sea in the absence of wind forcing unless a unrealistically low rate of bottom frictional dissipation is assumed. Both steady and time-periodic wind stresses invoke the upwind flow along the central trough of the Yellow Sea, independently of the presence of the oceanic current. The presence of oceanic currents very marginally alters the north-south gradient of the sea surface elevation in the Yellow Sea. Changes in the intensity and direction of the wind-induced mean upwind flow are hardly noticeable in the Yellow Sea but are found to be significant near Cheju Island where the gradient is reduced and therewith contribution of Ekman transport increases. In case of steady wind forcing circulation patterns such as two gyres on the slope sides, a cyclonic gyre on the western slope and an anticyclonic gyre on the eastern slope persist and the upwind flow composes part of the cyclonic gyre in the Yellow Sea. While in case of the time-periodic wind stress the appearance and disappearance of the patterns are repeated according to the time variation of the wind stress and the upwind flow accordingly varies with phase delay, mostly intensifying near the time when the wind forcing is approximately near the middle of the decaying stage.

Eutrophication and Seasonal Variation of Water Quality in Masan-Jinhae Bay (마산-진해만의 수질 부영양화 및 계절 변동)

  • Cho, Kyung-Je;Choi, Man-Young;Kwak, Seung-Kook;Im, Sung-Ho;Kim, Dae-Yun;Park, Jong-Gyu;Kim, Young-Eui
    • The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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    • v.3 no.4
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    • pp.193-202
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    • 1998
  • Water quality of Masan-Jinhae Bay was monitored from January 1996 to August 1997. The monitoring focused on the spatial and vertical gradients and seasonal changes of eutrophication parameters such as nutrients, DO and water transparency. Flagellate phytoplanktons persistently bloomed from April to October with monospecific or mixed algal blooms and dynamic algal successions were observed in this area. Algal blooms were highly correlated with salinity drops and made the water less transparent. Stratification of oxygen content was persistent through summer and oligo-oxygenation was developed in the bottom waters. Nutrient gradients were consistently maintained through the depth in summer and through spatial distribution from inner Masan Bay to outer Jinhae Bay in winter. Except the rainfall seasons, water quality was under the influence of the waste waters discharged from watershed around the Masan Bay. The waste waters would act as the primary factor for the water quality deterioration of the bay. Literature data for eutrophication were gathered and analyzed to review the water quality trends of the Masan and Jinhae bays since 1970. Annual mean COD and phosphate concentration consistently increased from 1975 to 1990 and decreased or dropped after 1991. The sediment of inner part of Masan Bay was dredged from 1991 to 1994 as a decontamination process and it is assumed that the dredging has weakened more or less the deterioration trend of the water quality of the bay.

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The Contents of Nitrogen, Phosphorus, Silicon Nutrient and Algal Growth Potential (AGP) in the Sediment of Taechong Reservoir (대청호 저토의 N, P및 Si 영양염 함량과 조류생장잠재력)

  • Cho, Kyung-Je;Shin, Jae-Ki
    • Korean Journal of Ecology and Environment
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    • v.34 no.2 s.94
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    • pp.106-118
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    • 2001
  • The chemistry of porewater and exchangeable nutrients of sediment was determined to define potential influence of sediment nutrients on the water quality and the phytoplankton growth in Taechong Reservoir in March and May of 2000. The sediment-water interface showed almost anoxic state, < 0.5 mg $O_2/l$. Conductivity of the porewater was higher 1.9${\sim}$2.6 fold than that of sediment, and its variation was greater in the shallow water. Eh ranged from -12mV to -148 mV and bulk density from $1.17\;g/cm^3$ to $1.30\;g/cm^3$ and they did not differ among stations. The water content in the sediment ranged from 58% to 72% and organics from 8% to 13%, and they were higher toward the lower part of reservoir. Soil texture was in the order of sand>clay>silt and sandy sediment accounted for 97% of the total sediment. The total bacterial numbers and diatom abundance were high in the downstream of the reservoir. In porewater and exchangeable nutrients of sediment, nitrogen and phosphorus were mostly consist of the particulate form. Inorganic nitrogen was mostly composed of $NH_4$. Nitrogen of porewater was mostly an inorganic form while exchangeable nutrients were composed an organic form. However, phosphorus was composed of dissolved organic fraction in the porewater while inorganic fraction in the exchangeable nutrients. Silicon content of sediment was much exchangeable nutrients with 63%, and it was higher than in the porewater. In summary, the sediments of Taechong Reservoir were mostly composed of organics and assessed to be a eutrophic state.

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A Model Experiment on the Basic Efficiency of Midwater Rope Trawl Net (로프 트롤 그물의 기본성능에 관한 모형실험)

  • Yae, Young-Hee;Lee, Byong-Gee
    • Journal of the Korean Society of Fisheries and Ocean Technology
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    • v.29 no.3
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    • pp.200-213
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    • 1993
  • A model experiment on a midwater rope trawl net which is used in the North Pacific to catch alaska pollack is carried out in the circulating tank to examine the basic efficiency of the net. The prototype is the net used by M/S Hanil(1, 179GT, 2, 700PS), a Korean trawler. The model net was made according to the Tauti's Similarity Law of Fishing Gear in 1/100 scale by considering the condition of the tank. To measure the basic efficiency of the standard model net, the vertical opening and width between some points marked on the net were measured, and the hydrodynamic resistance were determined. Then the constructive conditions of the net were varied as follows and the factors were measured again to compare the efficiency of those nets with that of the standard net(A-1 type) front weight multiplied 1.5 times: A-2 type. buoyancy and depressing force multiplied 1.7 times: A-3 type. front weight multiplied 1.5 times on A-3 type: A-4 type. depressors rigged at ground rope: B type. cod-end stuffed with cashmylon wad: C type. The results obtained can be summarized as follows: 1. The vertical opening at the center of head rope was steeply decreased with the flow velocity increasing and the vertical opening H(m) can be expressed in H=1.2v super(-1.2)(v : flow velocity in m/sec). The width of the net varied a little when the flow velocity was over 0.4m/sec, and the width of net mouth showed about 37% of the distance between the fore tips of net pendant. The shape of net mouth was almost a circle at 0.2m/sec and then steeply flatted elliptically with the flow velocity increasing and the area of mouth S(m super(2)) can be expressed in S=(1.65-2.3v)$\times$10 super(-2). The hydrodynamic resistance of the net increased almost linearly with the flow velocity increasing and the resistance R(kg) can be expressed in R=3.2$\times$d/l$\times$abv. where d/l denotes the mean of d(diameter of netting twine) and l(length of a leg in a mesh) from wing tip to the end of bag-net except cod-end on the side pannel, and a denotes the strectched circumference of the net at the fore end of a meshed part and b the stretched length of the whole net from wing tip to the end of cod-end. 2. In the condition-varied nets, the vertical opening of head rope showed some increase in every type net except the C type, and the increase showed the greatest in the B type by 30~54%, whereas it showed decrease in the C type by 5~10%. Variation of the area of net mouth showed almost the same tendency as the vertical opening and the increase showed the greatest in the B type by 20%, whereas it showed decrease in the C type by 12%. Hydrodynamic resistance showed some increase in every type compared with the standard net, and the rate of increase indicated 5~10% in the A-2, A-3 and A-4 type, 22% in the B type and 3% in the C type.

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Physio-Chemical Studies on the Maturity of Hot Pepper Fruits - Part VI. Effects of Cation on Growth and Important Components - (신미종(辛味種) 고추의 성숙(成熟)에 따른 생리화학적(生理化學的) 변화(變化)에 관(關)한 연구(硏究) - [제6보(第六報)] 성장(成長)과 주요성분(主要成分)의 함량(含量)에 미치는 Cation 영향(影響) -)

  • Lee, Sung-Woo;Kim, Kwang-Soo;Kim, Soon-Dong
    • Applied Biological Chemistry
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    • v.18 no.4
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    • pp.234-238
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    • 1975
  • To determine the effect of canons on growth and major components of hot pepper fruit, various combinations of K, Ca and Mh concentration in culture media were employed. The results analyzed by using binary interaction method were: 1. For the ideal condition for growth, the plant height was found by 57% K-435 Ca in KCa group and $58.5%\;K^++41.5%\;Mg^{++}$ in KMg group. The number of node was showed by $59%\;K^++41%\;Ca^{++}$ and $60%\;K^++40%\;Mg^{++}$. 2. The ideal condition for the maximum yield was by $60%\;K^++40%\;Ca^{++}$ and $62%\;K^++38% Mg^{++}$. For matured fruit yield, $57%\;K^++43%\;Ca^{++}$ and $63%\;K^++37%\;Mg^{++}$ was found ideal. 3. There were no significant differences in the amount of free sugars and capsaicin between tge treatments. 4. The nitrogen level was almost constant in all treatments however, the ratio of Fe/Mn in each treatment was showed from 2 to 3.

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The Contamination Characteristics of the Nanji Uncontrolled Landfill and its Surrounding Hydrogeologic Environment (난지도 매립지 주변 지하수환경의 오염 특성에 관한 연구)

  • 이철효;한정상
    • Journal of the Korean Society of Groundwater Environment
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    • v.3 no.1
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    • pp.27-36
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    • 1996
  • The Nanji landfill is one of the biggest uncontrolled landfill in terms of its size and scale in the world. Because the landfill was constructed on the very vulnerable alluvial deposit installing no pollution control systems such as bottom liner and leachate collection systems, it has caused a serious adverse effect to near-by groundwater and surface water systems. A through remedial investigation comprising plume detection and site-characterization was performed to design the remedial measure. As a part the investigation, comprehensive water quality study was conducted, using ten existing observation wells and one bundle type monitoring well, to determine the contaminant indicators for the plume delineation and to define the vertical and horizontal variation of specific contaminants via distances from the landfill. The results clearly shows that EC and temperature are a good pollution indicators and the vertical concentrations of specific contaminants measured in the fully screened wells are 20 to 90% more than those measured at the same depth in bundle type well which is located just 2 m apart. This paper presents a cost effective monitoring and sampling method to define the contaminant plume and obtain a basic data for leachate control measures.

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Muscuoloskeletal Disorders of Korean Fire Fighters: Applicants for Public Worker's Compensation from 2011 to 2013 (소방공무원의 근골격계 질환: 2011년~2013년 공상신청 분석)

  • Yoon, Jangwhon
    • Fire Science and Engineering
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    • v.30 no.3
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    • pp.133-137
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    • 2016
  • The aims of this study were to analyze the Korean fire fighters' applications for the public worker's compensation between 2011 and 2013 and to suggest a feasible solution for prevention of work-related musculoskeletal disorders. The Korean Ministry of Public Safety and Security provided the complete list of fire fighters' application from January 2011 to December 2013. 510 applicants with chief complaint of musculoskeletal disorders were screened out of all 1596 applicants. Male applicants were 92%. Fire fighters in their early 40's applied most frequently, followed by those in early 30's. Musculoskeletal disorders of fire fighters were reported most frequently in May and June. Regionally, Seoul had most applicants and Jeonbuk showed the highest prevalence. Low back was the most frequently reported body part followed by the knee. Ligament was insured most frequently followed by vertebral disc and bone. The fire fighter's injury occurred while fire extinguish (38.3%), emergency medical service (37.7%), rescue (12.4%), and other duties. Result of this study suggests further investigation on the large variation in regional prevalence and on the injury mechanism of musculoskeletal disorders especially during the fire extinguish and emergency medical service.

Comparison of Rice Yield and Grain Quality Characteristics between Mature and Reclaimed Paddy Fields in Honam Plain Area (호남평야지 숙답과 간척답의 수량 및 미질 특성 비교)

  • 정진일;이선용;김종호
    • KOREAN JOURNAL OF CROP SCIENCE
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    • v.40 no.3
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    • pp.382-390
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    • 1995
  • To compare the rice yield and grain quality characteristics between mature(MPF) and reclaimed paddy field(RPF), grain yield and its components, some physicochemical properties of rice grain and palatability of cooked rice were investigated for Dongjinbyeo grown at three different locations of mature and reclaimed paddy field, respectively, in south western part of Korea. Variation of culm length in mature paddy area was larger than that in reclaimed saline area. Panicle number per m$^2$ in RPF was more then that in MPF but grain number per m$^2$, filled grain ratio and 1, 000-grain weight in RPF were lower than those in MPT. Average yield of milled rice in RPF was 12% lower than that in MPF (5.l1t /ha). Daejeon showed the highest yielding among MPF and Yeongam reveald the highest grain production among RPF. RPF rices had slightly higher carbohydrate content and alkali digestibility but lower protein, fat and amylose content compared with MPF rices. RPF rices also exhibited higher mineral contents, Mg/K ratio, peak and hot viscosity compared with MPF rices. RPF rice showed slightly poor apparent grain quality but a little better eating quality of cooked rice compared with MPF rice.

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Relative Movement of Major Elements on the Weathering of Rocks (암석의 풍화에 따르는 주요성분의 상대적 이동)

  • Nam, Ki-Sang;Cho, Kyu-Seong
    • Economic and Environmental Geology
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    • v.26 no.1
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    • pp.67-81
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    • 1993
  • This dissertation is a basic research on the degradation of rocks and aims at clarifying the relations between the progression of degree of weathering and the variation of chemical composition. The author wants to make clear the degradation of rocks and the process of formation of sedimentary rocks from a standpoint of elucidation of migration of elements. This study is considered to be significant not only as a part of research on the distribution of earth crust materials but as the petrogenesis of rocks. The chemical studies on the weathered rocks have been started relatively early and there are not a few researches on them: Goldich, 1938; Harris, et al., 1966; Ruxton, 1968; Berner, et al., 1982; Kanuss, 1983; Lasaga, 1984; Siagel, 1984. The degree of migration of elements in weathering is the composite result of various factors. Because, at the present time, it is difficult to clarify the individual and composite effects of each factor theoretically and quanititatively, we must accumulate empirical data and use them relatively. In such consideration the author acquired some data of chemical weathering from the chemical analysis of granitic and basaltic rocks in and around Fukuoka city, Japan and granitic rocks in and around Chonju and Iri cities, Korea. Because both rock types studied can be considered as representative materials of acidic and basic rocks compsing the earth crust, it is significant to examine the phenomena of weathering of both rock types. The following results are obtained from the analysis and examinations of chemical compositions of the original and weathered rocks. The loss rate of major elements has no uniformity, but the following relation holds in general; Ca, Na> K, Si> Mg> Fe, Al. As weathering proceeds, the ratio of $Al_2O_3/CaO$ shows increasing phenomena, and that of $Na_2O/CaO$ decreasing. The range of migration of composition is broad in basaltic rocks but narrow in granitic rocks. The reason is that the chemical weathering of basaltic rocks progresses more easily than that of granitic rocks. The chemical weathering potenitial index of basaltic rocks in larger than that of granitic rocks. The reason is that the chemical weathering of basaltic rocks proceeds more easily than that of granitic rocks. In weathering, the decrease of mobile cations such as $Ca^{2+}$, $Na^{2+}$, $Mg^{2+}$ and the increase of $H_2O$ in basaltic rocks are more obvious than in granitic rocks.

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A Case Study on Foraging Behavior of Oriental White Storks (Ciconia boyciana) in the Variation of Prey Density and Water Depth (먹이 밀도와 수심에 따른 황새(Ciconia boyciana)의 섭식 행동에 대한 사례연구)

  • Sung, Ha-Cheol;Kim, Jung-Hee;Cheong, Seok-Wan;Kim, Su-Kyung;Jo, Jee-Yeon;Cheong, Mi-Ra;Choi, Yu-Seong;Park, Shi-Ryong
    • Korean Journal of Environmental Biology
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    • v.27 no.2
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    • pp.155-163
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    • 2009
  • The Oriental white stork (Ciconia boyciana) is an endangered species in Korea as well as in the world. In order to provide information on foraging habitats for releasing storks to the wild, we studied the foraging behavior of the species according to different food densities and water levels. We released two individuals, male and female, after enclosing a study site with a fence and cutting out a part of two or three primary feathers. Research was conducted from 20 June to 16 August 2008 at Whawon-ri, Mewon-myung, Chungcheongbuk-do, South Korea. We investigated habitat patch usage, foraging efficiency, and foraging methods of the feeding individuals in the different food densities and water levels. The storks invested more for foraging time and trials, and they captured more food in a habitat of high food density than others. The female invested more time and captured food most in a habitat of lowest water depth while the male in a habitat of middle water depth. However, foraging efficiency did not differ significantly among habitats of food density and water depth, and only differed between male and female by ways of foraging method. From this study we suggest that the storks select foraging habitats and foraging methods under different conditions of food density and water depth.