• Journal of the Korean Society of Groundwater Environment
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• v.5 no.2
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• pp.66-79
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• 1998

This study purposes to elucidate the characteristics of local water quality and the evolutional process of the spring water have been studied with the samples from 55 selected springs, from the coast region to the Baegrogdam, a caldera lake of Halla mountain in Cheju Island. Results of hydrochemical analyses in the 55 spring water show that Gwaneumsa is pollued with high hydrogen concentration, and spring waters from Yusuarmchun, Jangsumul, Dukjisemmul, Sinch'onk'nmul, Youngchunsa, Woonyangchun, Harwontongmul, Dongheamul, Seakdalsengsu, Andukkyekok, Dotimul, Kinmul, Harkangmul and Jungkeummul are polluted by the pollution sources from the surface surrounding ground. Spring waters of Samyang3suwon, Meungbusa, Sernurungmul, Tosanmul, Jungkeummul, Kwakgimul, Aewolharmul, Konemul and Nokgomul are also polluted from the sea water intrusion. The electrical conductivity, pH and the concentration of nitrate nitrogen and bicarbonate increase when the precipitation increases, but the concentration of sodium, chloride and sulphate decrease when the precipitation increases. The concentrations of potassium, magnessium and calcium are nearly independent of the precipitaion. Quality characteristics of spring water show complicated group of spring water through piper's trilinear diagram. The high mountain region consists of groups of sodium or potassium type and bicarbonate type; the middle mountain region consists of groups of sodium or potassium type and no dominant type; the low mountain consists of groups of no dominant type and sulfate or nitrate type; the coast region consists of groups of sodium or potassium type and chloride type or no dominant type. These characteristics indicate that the spring waters are changed from bicarbonate type in the high and middle mountain regions into non-bicarbonate type in the coastal region, as the precipitated waters flow downslope.

• Industry Promotion Research
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• v.6 no.3
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• pp.49-57
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• 2021

The purpose of this paper is to examine the editions of 'Jeokcheonsu', the best Myoungri Classic in name and reality, that was featuring dozens of annotations and interpretations from the Qing Dynasty to the Republic of China, and modern times. The original author of 'Jeokcheonsu' was Gyeongdo of the Song Dynasty, firstly annotated by Yugi of the late Yuan Dynasty to Early Ming Dynasty, and Im Cheolcho of the Qing Dynasty annotated again. However, several observations in the original text suggest that the author's period of writing is postulated since the middle of the Ming Dynasty, and if the book is not likely to belong to the Song Dynasty, the author is also unlikely to be Gyeongdo of the Song Dynasty. Besides, if you look at the statements of Jin Soam and Jeong Jiwoon, who published the early editions of 'Jeokcheonsu', there are many negative opinions about the usual author recognition. In this study, we conducted a comparative analysis of the four existing editions of 'Jeokcheonsu', 'Jeokcheonsu-Jibyo' edited and published by Jin Soam, 'Myeongri Suji Jeokcheonsu' revised by Jeong Jiwoon, 'Jeokcheonsu-Cheonmi' annotated by Im Cheolcho, and 'Jeokcheonsu-Jingui' edited and published by Seo Rako. It is hoped that this study will help us understand 'Jeokcheonsu' more deeply and help us with related research, such as comparative studies of annotations in the future.

• KOREAN POULTRY JOURNAL
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• v.40 no.10
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• pp.87-91
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• 2008

지난 8월 29일 대전 유성 소재 베스트웨스턴 레전드 호텔에서 '위기에 처한 채란업 대응전략' 이란 주제로 제 11회 전국채란인대회를 개최했다. 본고는 이 자리에 참석한 전국 채란인을 대상으로 설문조사를 실시해 분석한 내용이다. 본 설문에 참여한 농가는 총 143명으로 설문에 응한 채란인들의 사육규모는 평균 4만3천수로 지난 2005년 10월 채란인대회 때 4만7천수 보다 규모가 줄었음을 알 수 있다.

• Journal of Life Science
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• v.22 no.3
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• pp.324-331
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• 2012

Bacteriological examination of spring water in Jeju City was conducted. A total of 21 spring water samples were collected from January to April, 2010. During the study period, the range of temperature was 0.6 to $15.4^{\circ}C$, and the results of the analyses showed that hydrogen ion concentrations (pH) for spring water were 0.43 to 7.9. Salinity levels for the samples averaged from 3.0 to 1.64%, and levels of water-dissolved oxygen were 1.85 to 6.06 mg/l. The range of total coliforms in spring water samples at 21 stations located in the designated spring water were <1.8->1,600 MPN/100 ml. Furthermore, the range of geometric means of total coliforms was 9.9-151.6 MPN/100 ml, while the range of fecal coliforms in spring water samples at 21 stations located in the designated spring water area was <1.8->1,600 MPN/100 ml. Finally, the range of geometric mean of fecal coliforms was 3.1-151.6 MPN/100 ml. The level of microbial contamination was examined in 21 samples for indications of bacterial contamination such as heterotrophic bacteria, Escherichia coli O157:H7, Salmonella spp., Vibrio parahaemolyticus, Staphylococcus aureus, and Shigella spp. were frequently detected in the spring water. Salmonella spp., Shigella spp., Vibrio parahaemolyticus, and S. aureus were detected in the range of $0-0.5{\times}10^1$, $0-0.1{\times}10^1$, $0-0.1{\times}10^1$, and $0-0.3{\times}10^1$ CFU/ml, respectively, while E. coli O157:H7 was not detected in the examined spring water samples.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.3 no.1
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• pp.14-20
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• 1991

Accurate estimation of irregular wave transformation when the waves propagate from deep water to shallow water region is very important for the design of coastal structures and establishing beach erosion control. In this study. the transformation of directional spectrum is tested numerically using a conservation equation for energy flux and. based upon the joint distribution of wave height. period and wave direction. shoaling effects are predicted in the shallow water region. The applicability of the proposed procedure is verified through comparison with field observation data.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.35 no.6
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• pp.1237-1246
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• 2015

A novel technique was proposed to calculate fluxes accurately by separation of flow area into a part of step face which is dominated by flow resistance of it and an upper part which is relatively less affected by the step face in analyzing shallow-water flows over discontinuous topography. This technique gives fairly good agreement with exact solutions, 3D simulations, and experimental results. It has been possible to directly analyze shallow-water flows over discontinuous topography by the technique developed in this study. It is expected to apply the developed technique to accurate evaluation of overflows over weirs or retaining walls (riverside roads) and areas flooded by the inundation in the city covered in discontinuous topography.

• Journal of the Korean Society of Marine Environment & Safety
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• v.14 no.2
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• pp.157-162
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• 2008

The ship's maneuverability is the important factor to avoid ship's collisions. The ship's maneuverability is usually measured in a deep water, and the turning ability is decreased and the course stability is improved in a shallow water. The variation of the turning ability could cause the risk of collision. In this paper, we proposes application technique of Variable Safe-Guard Ring to consider the shallow water effect and to be simple to estimate the grade of collision risk simultaneously. Through the mathematical simulation, the availability of new method was varified. Therefore this method is expected enough to support a maneuver for collision avoidance.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.20 no.1
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• pp.121-127
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• 2008

Numerical experiments with weakly nonlinear MIKE21 BW module and fully nonlinear FUNWAVE model are performed to identify the nonlinear characteristics of Boussinesq models with varying nonlinearity. Generation of waves with varying amplitudes, nonlinear shoaling and wave propagation over submerged bar experiments showed the importance of nonlinear model in shallow water where nonlinearity becomes prominent. Fully nonlinear model showed the nonsymmetrical wave form more clearly and gave larger shoaling coefficients than those of weakly nonlinear model.

• Proceedings of the Korea Water Resources Association Conference
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• 2016.05a
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• pp.64-64
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• 2016

하천은 인간에게 용수의 이용 및 하천호안의 휴식처로써의 이용을 통해 직접적인 영향을 주고, 하천구조물의 심미적 영향, 랜드마크로써의 역할을 통해 간접적인 영향을 준다. 또한, 하천은 하천생태계에 서식하는 동 식물에게 영향을 준다. 그러나 하천유사로 인해 통수능이 감소하고, 하천구조물 주변에 침식을 야기할 뿐만 아니라, 댐과 저수지에 유사의 퇴적으로 저수용량의 감소시킨다. 그러므로 이를 예측하는 것은 경제적, 환경적으로 중요하다. 하상변동의 모의를 위해 기존의 2차원 모형은 만곡흐름에서 유동의 helical flow를 고려하지 않아 예측이 부정확하였다. 본 연구에서는 천수방정식을 이용한 하상변동 수치모의에 helical flow의 영향을 고려하였다. 하천과 같은 천수영역에서의 흐름 및 하상변동을 해석하기 위하여 수심평균 된 Navier-Stokes equations인 천수방정식을 이용하였다. 지배방정식은 곡선 좌표계에서 유한체적법으로 차분하였고, 비엇갈림격자를 사용하였다. 지배방정식의 닫힘 문제를 해결하기위해 0-방정식 난류모형을 사용하였고, "time marching" 기법의 적용을 위해 계산단계분할 방법을 이용하였다. 비엇갈림격자의 사용으로 인해 검사체적의 면에서의 유속이 필요하여 pressure-velocity coupling을 사용하여 유속의 진동을 줄였다. 또한, 만곡부의 helical flow를 모의하기위해 helical flow intensity model을 도입하였다. 앞에서 계산한 흐름을 바탕으로 유사량 산정공식과 Exner 방정식을 이용하여 하상변동을 모의하였다. 흐름의 검증, helical flow의 영향에 대한 확인, 하상변동의 적용을 위해 선행연구의 실험이 사용되었다.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.43 no.6
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• pp.749-762
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• 2023

A depth-integrated model with an approximate Riemann solver for flux computation of the shallow water equations was applied to hydraulic jump experiments. Due to the hydraulic jump, different flow regimes occur simultaneously in a single channel. Therefore, the Weisbach resistance coefficient, which reflects flow conditions rather than the Manning roughness coefficient that is independent of depth or flow, has been employed for flow resistance. Simulation results were in good agreement with experimental results, and it was confirmed that Manning coefficients converted from Weisbach coefficients were appropriately set in the supercritical and subcritical flow reaches, respectively. Limitations of the shallow water equations that rely on hydrostatic assumptions have been revealed in comparison with hydraulic jump experiments, highlighting the need for the introduction of a non-hydrostatic shallow-water flow model.