• Korean Journal of Ichthyology
• /
• v.5 no.1
• /
• pp.85-95
• /
• 1993

Sexual dimorphism of the matured chum salmon, Onchorhynchus keta, have been studied based on biometrical measurements and osteological characters. Male chum salmon has an elongated and hooked upper jaw and canine-like teeth on the upper and lower jaw. The ratios of snout length (SnL) and upper jaw length (UJ) to head length of male were larger than those of the female, whereas eye diameter (ED) and postorbital part of head (CK) of the male were smaller than those of the female's. The ratios of body depth, caudal peduncle depth, anal fin length and adipose fin length to the standard length (PBL) of the male were also larger than those of the female. On sexual dimolrphism was detected in number of fin rays, gill rakers and pyloric ceaca, where as number of lateral line scales and caudal vertebrae of the female was larger than those of the male. Glossohyal and vomer bones has no sexual difference. The ratio of width to length of supraethmoid bone of the male was larger than that of the female. The ratio of frontal part to posterior part of parasphenoid bone of the male was smaller than that of the female.

• Korean Journal of Ichthyology
• /
• v.29 no.3
• /
• pp.224-228
• /
• 2017

Two specimens of Ruvettus pretiosus (227.0 and 238.3 mm in standard length), belonging to the family Gempylidae, was firstly collected by using a gill net from the eastern coastal waters of Jejudo Island, Korea in November 2013. This species is characterized by having the following morphological traits: XV, 17~19+2 dorsal fin rays; II, 15~16+2 anal fin rays; belly keeled between pelvic fin and anus; body covered with cycloid scales, interspaced with rows of sharp bony tubercles. R. pretiosus can be easily distinguished from three Korean Snake mackerels (Thyrsitoides marleyi, Rexea prometheoides and Gempylus serpens) by having belly keeled between pelvic fin and anus, and cycloid scales covered the body and interspaced with rows of sharp bony tubercles. Based on morphological and molecular approaches, the specimens were identified as R. pretiosus. We propose new Korean names, "Gi-reum-chi-sok" and "Gi-reum-chi" for the genus and species, respectively.

• KSCE Journal of Civil and Environmental Engineering Research
• /
• v.37 no.2
• /
• pp.467-474
• /
• 2017

Each river confluence has the inherent hydraulic and mixing characteristics coming from its bathymetry and topography. It is necessary to make the measurement covering the spatial extent of studying area in order to catch these 2-dimensional intrinsic characteristics. This study focuses to investigate the hydraulic and mixing characteristics at the confluence of Nakdong and Geumho River, from field measurement of flow, water quality, and suspended particle distribution with ADCP (Riversurveyor M9), multi-parameter water quality sonde (YSI6600V2), and submersible system for in-situ observations of particle size distribution and volume concentration (LISST : Laser In-Situ Scattering & Transmissometry), respectively. From the results, it can be found that the field measurement of suspended particle and water quality distribution can be the useful approach to catch the hydraulic and mixing characteristics at a river confluence.

• Proceedings of the Korea Water Resources Association Conference
• /
• 2008.05a
• /
• pp.2228-2232
• /
• 2008

삽교천 수계에 위치하고 있는 지점들은 유역면적이 작은 지점들과 삽교천 갑문의 영향에 의한 배수영향을 받는 지점들로 인하여 수문관측에 어려움이 많아 수위-유량관계곡선개발이 매우 어려운 지점들이다. 따라서 2007년 유량측정성과들을 이용하여 보다 정확한 수위-유량관계곡선개발을 하기 위해서 각 지점별 유량측정성과의 기준측선수, 최대구간유량비, 불확실도 분석 등을 통해 유량측정성과를 분석하였으며, 연유출률 분석, 상 하류 유량 비교, 평 저수시 동시유량 검토, 수위-유량관계곡선 불확실도 분석으로 수위-유량관계곡선의 신뢰도를 검토하였다. 금회 삽교천 수계에서 유량측정된 지점은 수촌, 원평, 매곡, 온천, 충무교 지점이며, 충무교 지점을 제외한 4개 지점은 2007년 수위자료를 이용하였고, 충무교 지점은 충무교 지점 하류의 보 영향으로 계기수위 0.855m(GZF)이상의 수위를 보이는 기간인 7월 19일$\sim$10월 24일까지 기간의 수위자료를 이용하여 순 유출률을 산정하였다. 각 지점별로 순 유출률을 보면 수촌 64.4%, 원평 44.1%, 매곡 56.3%, 온천 56.1%, 충무교 88.2%로 산정되었으며, 대체적으로 적절한 연 유출률을 보이고 있다. 본 연구에서 수행한 삽교천 수계 5개 지점의 측정성과를 이용한 유출특성 분석 결과, 기존의 성과에 비하여 좋은 결과를 얻은 것으로 판단되지만, 본 연구에서 수행한 유량측정에서도 많은 문제점이 발생하였기 때문에 이런 경험과 기술들을 지속적으로 축적한다면 향후 더 정밀한 유량측정성과를 확보할 수 있을 것으로 판단되며, 효과적인 치수 및 이수계획의 수립 등 수자원 개발에 가장 기초가 되는 정확한 수문분석 자료의 확보를 위한 기반을 마련할 수 있을 것이다.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
• /
• v.9 no.2
• /
• pp.37-48
• /
• 1991

In this study, conventional network adjustment and combined network adjustment methods for single network adjustment methods for single network and centric combination network were compared by the analysis of root mean square error and standard error ellipse of observed points. It can be concluded from this study that for conventional surveying methods, the accuracy is in theorder of trilateration, traverse and triangulation, and for the case of combined surveying method, the accuracy is in the order of multilateration surveying, combined traverse and combined triangulation-trilateration surveying. And when establishing new control points, the accuracy can be improved by increasing redundant observations of centric combination network instead of using the single network. Also, in case of combined traverse surveying by adding observable laterals, accuracy level of trilateration could be achieved, and it was found that traverse is effective for large areas where sighting is easy, and combined traverse surveying is effective for urban areas where sighting is difficult.

• Geophysics and Geophysical Exploration
• /
• v.3 no.3
• /
• pp.88-93
• /
• 2000

The present study may be summarized as follows. By means of a pole-pole electrical survey, major geological features, i.e, fresh rocks, fractured & weak & saturated rocks, fresh water bearing aquifer, were successfully delineated in the surveyed area of a granite region in Korea. The subsequent Schlumberger sounding and drilling confirmed the existence of the acquifer at 60 m depth as expected. But one more minor acquifer which does not show up in the resistivity depth section was met at 100 m depth. A simple forward modelling leads the authors to believe that any other electrode configuration, e.g., Wenner, Schlumberger, dipole-dipole, pole-dipole, would not detect the deeper aquifer. Under these circumstances, further studies remain to be done in connection with the spatial resolution in the vertical direction.

• Proceedings of the Korea Water Resources Association Conference
• /
• 2015.05a
• /
• pp.193-193
• /
• 2015

오염원과 취수원이 인접한 위치에 존재하는 국내 하천 같은 경우 취수 시설의 안전한 관리를 위하여 오염물의 2차원 혼합 거동에 대한 연구가 필요하다. 하천에서의 오염물 혼합 거동을 분석하기 위하여 일반적으로 농도와 분산 정보 수집을 위한 추적자 실험을 수행해왔다. 기존에 수행된 추적자 실험들은 형광염료, 방사선 물질, 고형 물질 등과 같은 추적자를 인위적으로 주입하여 사용하였다. 그러나 수온, 전기전도도(electrical conductivity), 이온화 물질 등과 같은 자연 추적자(natural tracers)를 이용하는 추적자 실험은 인공추적자 물질을 대체할 수 있는 방안으로서, 기존 추적자 실험과 비교하여 경제적, 환경적인 효과와 하폭이 넓은 중규모 이상의 하천에서도 수행할 수 있다는 장점을 가지고 있다. 본 연구에서는 진천천과 금호강이 합류하는 낙동강 중류 구간에서 횡혼합 연구를 위하여 전기 전도도 추적 실험을 수행하였다. 강정고령보 직하류에서 낙동강 좌안쪽에서 합류하는 금호강과 진천천의 경우 인근 공업단지와 하폐수처리장으로부터 많은 비점오염원과 점오염원이 유입된다. 두곳의 지류에서 모두 높게 측정되었던 전기전도도를 자연 추적자로 선택하였다. 지류의 경우 전기전도도를 측정할 수 있는 센서를 측정 지점에 설치하여 측정하였으며, 본류인 낙동강의 경우 정해진 측선을 따라 센서가 고정된 보트를 이동하며 데이터를 취득하였다. 지류인 금호강과 진천천의 경우, 합류 전 전기전도도의 농도의 횡분포는 균일한 분포를 나타냈으며 농도의 평균값은 합류 전 낙동강 본류의 기저농도 보다 더 높은 값을 나타내었다. 지류 합류 이후의 낙동강 본류에서는 지류로부터 유입된 오염물질로 인하여 횡방향으로 불균등한 전기전도도 농도 분포를 나타내었으며 오염물질이 점점 하류 쪽으로 이동하면서, 횡방향 농도경사의 크기가 줄어들었다. 유관모멘트법을 농도곡선에 적용하여 횡방향 분산계수를 산정하였다. 산정된 횡분산계수의 값은 Rutherford (1994)가 제안한 분산계수의 범위에 포함되는 것으로 나타났다.

• Journal of the Korean Geotechnical Society
• /
• v.25 no.4
• /
• pp.5-17
• /
• 2009

In HWAW method, experimental dispersion curve is obtained through time-frequency analysis, and inversion procedure is based on the forward modeling which considers full wavefield. Therefore, it enables us to use relatively short testing setup and has advantage for two dimensional subsurface imaging compared with another surface wave methods. Numerical study was performed to verify that the HWAW method can be applied to non-horizontally layerd soil structure. The experimental dispersion curves obtained from HWAW method agreed with the theoretical dispersion curves based on full wavefield. Experimental dispersion curves are mainly more affected by the region between two receivers than by the region from source to the first receiver. Fluctuation phenomena of dispersion curve can be reduced by adequate receiver spacing setup. From numerical study, it was thought that reliable Vs distribution map can be constructed by HWAW method and finally subsurface imaging was tried in the real field.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
• /
• v.24 no.1
• /
• pp.27-36
• /
• 2006

Most of domestic multipurpose dams were basin area to be large, therefore, soil loss were occurred by downpour in the rainy season, They have caused to accumulate sediments on the river and dam reservoir that brought the decrease of storage volume and difficulties of the quality management of water. Until now, the measurement cycle of sediments surveying was long and it was designed to use surveying the degree of sediments, Thus there were many difficult things to secure accuracy. In this study, it was intended to analyze the origin position tracing of sediments and the movement route, for this purpose, aerial LiDAR technology was applied to precise sediments surveying. The amount and location of soil loss were evaluated by classified properties of soil, land-cover, and topographical conditions in detail. Therefore, the reliance could be maintained in analyzing the route of soil loss by extracting the flow within a watercourse and using the advanced accurate DEM.

• Geophysics and Geophysical Exploration
• /
• v.11 no.3
• /
• pp.184-196
• /
• 2008

We perform MT soundings in Bendigo, the northern part of Victoria, Australia, to investigate the deep subsurface geologic structure. The primary purpose of this survey is to figure out whether the discontinuity such as faults extends northward. The time series of MT signal were measured over 11 days at 71 measurement stations together with at remote reference, which help enhance the quality of impedance estimation and its interpretation. The impedances are estimated by robust processing using remote reference technique and then inverted with 2D MT 2D inversion. We can see that known faults are clearly imaged in MT 2D inversion. Comparing resistivity images from MT 2D inversion with interpreted boundary from reflection seismic exploration, two interpretations match well each other.