• Journal of Environmental Impact Assessment
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• v.28 no.2
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• pp.129-140
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• 2019

Majangcheon is a small agricultural stream which is located in Chuncheon-si, Gangwon-do. To understand ecological characteristics of Majangcheon as biological habitats, we surveyed its physical environment and fishes from June 2016 to September 2016. The altitudinal difference between lowest and highest point of the stream was 3 meters and the first-order stream under a map drawn on a scale of 1:25,000. The flow rate of stream was slow in overall with $0.09-0.48m{\cdot}s^{-1}$. More than 50% of clay were found in all points except for the point St. 3 in the riverbed structure surveyed. A total of 2,532 individuals of 22 species in nine families were collected from Majangcheon. Of them, stillwater-living species (Acheilognathinae and Carassius auratus) and floating species (Zacco platypus and Oryzias sinensis) were mainly collected. In Majangcheon, thus, both of stillwater-living and floating fishes were specifically coexisted. The correspondence analysis, based on fishes collected from Majangcheon and past research, showed that Majangcheon is closer to the flat streams in Gyeonggi-do rather than the mountainous streams in Gangwon-do but it appeared as an independent group from those of two regions. As a result, Majangcheon is a stream with specificity of fish community.

• The Korean Journal of Zoology
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• v.37 no.4
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• pp.545-553
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• 1994

척추동물의 초기 발생에 관여하는 물질로 알려져 있는 retinoic acid(RA)를 Xenopus 배(embryo)에 처리한 결과, 체절의 형성에 이상 발생이 나타났다 즉 낭배 초기에 RA에 노출된 개체의 체절은 대조군의 화살머리 모양((((() 대신 기등 모양(1111)을 형성하고 있었으며, 고농도일수록 직선에 가까운 모습을 하고 있었다. 신경배 시기에 노출된 개체의 체절은 정상적인 분절이 이루어지지 않았으며, 이들 이상 체질의 위치는 처리 시기에 따라 다르게 나타났으나 농도에는 영향을 받지 않았다. 그러나 분절 과정중 일어나는 체절 세포들의 회전은 RA에 의해 억제되지 않았다. 이와 같은 결과는 체절의 형성에 분절 이전의 세포의 행동을 주도하는 프로그램과 분절을 주도하는 프로그램이 분리되어 있음을 암시한다. 한 가지 특이한 사항은 열처리 등으로 유발된 혼란이 수 개의 체절에 국한되어 나타나는 점과는 달리 RA의 처리는 어느 지점 이 후부터 모든 체절에 혼란을 야기시킨다는 점이다. 이와 같은 연속적인 분절의 흔란 현상은 RA가 다른 저해제에 의해 영향을 받는 유전자의 활동을 조절하는 전 단계의 유전자에 영향을 주기 때문인 것으로 사료된다. 또한 신경배 시기에 RA에 노출된 배의 a-cardiac actin은 정상적으로 발현되는데 비해 낭배 초기에 RA에 노출된 배는 감소된 양의 a-cardiac actin myNA의 축적을 보였다. 그러나 EFI-u은 RA의 처리 시기와는 무관하게 정상적으로 발현되었다.

• Proceedings of the Korea Water Resources Association Conference
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• 2023.05a
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• pp.211-211
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• 2023

본 연구에서는 지역빈도분석을 이용하고 있는 홍수량 산정 지침에서 활용되고 있는 전국대상의 강우관소에 대한 확률강우량과 강원지역에 위치한 강우관측소만을 대상으로 산정한 확률강우량을 비교하였다. 이를 위해서 강원도 지역의 48개 지점의 지속기간별 강우자료를 수집한 후, K-means 기법을 이용하여 6개의 군집으로 구분하였다. 강원도 대부분이 산악지형임을 고려해 산악효과를 야기하는 지형인자와 강우자료의 관계를 파악하였다. 국가수자원관리종합정보시스템에서 수집한 강우자료를 사용하여 지속시간별 최대강우량과 산악효과를 야기하는 지형인자로 선정한 고도 이외에 위도, 경도를 각각 추가인자로 고려해 지역빈도분석을 수행하였다. 위 지형인자와 강우자료를 이용하여 수문학적 동질한 특성을 가지는 군집을 구성하였으며, 위도와 경도를 인자로 추가하면 더욱 강한 상관성을 보임을 알 수 있었다. 군집분석결과를 통해 모수를 추정하고 적절한 분포를 선택하였으며, 이상치검정과 적합도 검정을 통해 최종 분포를 결정하였다. 고도와 위도, 경도를 모두 고려해 이용한 지역빈도분석 결과 강원도의 실제 강우특성과 마찬가지로 고도의 높낮이에 따라 강우형태를 전국단위 지역빈도분석과 비교하였다. 최종적으로 현재 활용되고 있는 홍수량 산정 지침의 확률강우량과 강원지역에 위치한 강우관측소만을 대상으로 한 지역빈도분석의 차이의 발생원인과 강원지역에서의 특이성을 결론으로 제시하였다.

• Korean Journal of Ichthyology
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• v.25 no.4
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• pp.208-215
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• 2013

Host species preference of Acheilognathus signifer for spawning in freshwater mussels was investigated at the part of the Dalcheon Stream (site 1) and the Gaedaecheon Stream (site 2) in Chungcheongbuk-do, Korea from April to June (spawning period) 2011. The spawned mussel rate of A. signifer at the study site 1 (wild condition) was 63.6% in Lamprotula leai and 2.1% in Unio douglasiae sinuolatus. It was not found in Anodnta arcaeformis flavotincta and Lanceolaria grayana. The number of eggs, larvae, or both of A. signifer at the study site 1 (wild condition) was 1~41 ($12.0{\pm}9.21$) in L. leai and 6 in U. d. sinuolatus. As a result of experiment 1, A. signifer was only spawned in L. leai with 60% of spawned mussel rate and the number of eggs, larvae, or both was 1~19 ($6.8{\pm}5.44$). According to experiment 2, A. signifer was spawned in all mussels. Spawned mussel rate of A. signifer was 75.0% in L. leai, 42.9% in U. d. sinuolatus and 21.4% in A. a. flavotincta and the number of eggs, larvae, or both was 1~35 ($13.0{\pm}8.80$) in L. leai, 1~26 ($5.2{\pm}6.92$) in U. d. sinuolatus and 2~19 ($8.6{\pm}5.64$) in A. a. flavotincta. Experiment 3 showed A. signifer was solely spawned in L. leai and the number of egg was from 2 to 10 ($6.7{\pm}4.16$). This study confirmed A. singifer is not so much generalist as specialist. We found the most preference species for spawning in the mussels by A. signifer was L. leai.

• Korean Journal of Ecology and Environment
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• v.55 no.1
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• pp.84-98
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• 2022

Estuary is important in terms of biodiversity because it has the characteristics of transition waters, created by the mixing of fresh- and seawater. The estuarine water circulation provides a variety of habitats with different environments by inducing gradients in the chemical and physical environment, such as water quality and river bed structure, which are ultimately the main factors influencing biological community composition. If the water circulation is interrupted, the loss of brackish areas and the interception of migration of biological communities will lead to changes in the spatial distribution of biodiversity. In this study, among the sites covered by the Estuary Aquatic Ecosystem Health Assessment, we selected study sites where changes in biodiversity can be assessed by spatial gradient from the upper reaches of the river to the lower estuarine area. The α-, γ- and β-diversity of diatom, benthic macroinvertebrates, and fish communities were calculated, and they were divided into open and closed estuary data and compared to determine the trends in biodiversity variation due to estuarine circulation. As results, all communities showed higher γ-diversity at open estuary sites. The benthic macroinvertebrate community showed a clear difference between open and closed estuaries in β-diversity, consequently the estuarine transects were considered as a factor that decreases spatial heterogeneity of their diversity among sites. The biodiversity trends analyzed in this study will be used to identify estuaries with low γ- and β-diversity by community, providing a useful resource for further mornitoring and management to maintain estuarine health.

• Clinical and Experimental Pediatrics
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• v.46 no.8
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• pp.751-757
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• 2003

Purpose : Obesity is a significant health problem with medical and psychological consequences for children and adolescents. The purpose of this study was to assess the correlation between body fat percent using bioelectrical impedance(BI) and other variable methods. Methods : We measured height, weight, body mass index(BMI) and body fat percent by skinfold thickness(ST) and BI in 1,035(496 male; 539 female) children from seven to 18 years of age. The correlation coefficients between BI and each of the other different methods were obtained. The sensitivity and specificity to predict obesity by these several methods were studied. Results : Fat percent estimated by BI analysis and BMI showed a strong correlation(r=0.749). Fat percent estimated by BI analysis and ST showed a very strong correlation(r=0.835). At the 95th percentile cut-off point for BI, ST showed a sensitivity of 57.7%, and a specificity of 97.6% for estimating body fat. At the 95th percentile cut-off point for BI, BMI showed a sensitivity of 84.9%, and a specificity of 99.3% for estimating body fat. Conclusion : The fat percent estimated by BI analysis correlated strongly with ST or BMI. BI analysis is an objective and accurate method for estimating body fat in childhood obesity.

• Journal of Korea Water Resources Association
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• v.54 no.10
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• pp.835-848
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• 2021

In Jeju Island which has peculiarity for its geological features and hydrology system, hydrological factor analysis for the effective water management is necessary. Because in-situ hydro-meteorological data is affected by surrounding environment, the in-situ dataset could not be the spatially representative for the study area. For this reason, remote sensing data may be used to overcome the limit of the in-situ data. In this study, applicability assessment of MOD16 evapotranspiration data, Globas Land Data Assimilation System (GLDAS) based evapotranspiration/soil moisture data, and Advanced SCATterometer (ASCAT) soil moisture product which were evaluated their applicability on other study areas was conducted. In the case of evapotranspiration, comparison with total precipitation and flux-tower based evapotranspiration were conducted. And for soil moisture, 6 in-situ data and ASCAT soil moisture product were compared on each site. As a result, 57% of annual precipitation was calculated as evapotranspiration, and the correlation coefficient between MOD16 evapotranspiration and GLDAS evapotranspiration was 0.759, which was a robust value. The correlation coefficient was 0.434, indicating a relatively low fit. In the case of soil moisture, in the case of the GLDAS data, the RMSE value was less than 0.05 at all sites compared to the in-situ data, and a statistically significant result was obtained as a result of the significance test of the correlation coefficient. However, for satellite data, RMSE over than 0.05 were found at Wolgak and there was no correlation at Sehwa and Handong points. It is judged that the above results are due to insufficient quality control and spatial representation of the evapotranspiration and soil moisture sensors installed in Jeju Island. It is estimated as the error that appears when adjacent to the coast. Through this study, the necessity of improving the existing ground observation data of hydrometeorological factors is emphasized.

• Proceedings of the Korea Water Resources Association Conference
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• 2019.05a
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• pp.253-253
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• 2019

유사의 이동은 하천, 해안 지역과 같은 수계에서 하상의 변동, 침식과 퇴적을 일으켜 지형적인 변화를 초래한다. 유사의 이동은 유사의 특성과 유체의 유수동역학적 특성에 의해 결정되며 유체특성 간의 복잡한 상호 작용에 의해 변화한다. 유사가 가지는 점착성은 유사의 특성에 큰 영향을 끼친다. 입자의 크기가 매우 작은 점착성 유사는 그 표면이 가지는 전자기적 점착력에 의해 주위의 1차 입자나 다른 작은 알갱이들이 서로 뭉치는 응집과 충돌에 의해 크기가 작아지는 파괴의 과정을 겪는다. 이 과정을 응집현상이라고 하며 응집현상을 통해 점착성 유사의 크기와 밀도, 침강속도는 계속해서 변화한다. 따라서 점착성 유사의 응집거동 고려한 유사 이동 연구는 필수적이다. 과거 연구의 많은 사례에서 유사의 크기와 농도는 비례 관계를 가지는 것이 일반적이라 알려져 있다. 그러나 실제 현장에서 측정한 결과 유사의 크기와 농도가 반비례 관계를 가지는 특이점이 발견되었다. 실측 연구에서 발견된 응집거동에 따른 유사의 특성의 특이한 변화를 설명하기 위해 1차원 연직 수치 모형(1DV)을 이용하여 수치 실험을 수행하였다. 모의 수행 시, 흐름 조건을 크기와 방향이 일정한 순방향흐름(Current)에 특정 주기와 진폭을 가지는 진동 흐름(Oscillatory Flow)을 추가하여 진행하였다. 플럭의 성장과 그에 따른 입자의 크기는 많은 현상에 영향을 받는다. 그 중 응집현상의 응집 과정과 파괴 과정 중 어떤 현상이 더 우세한지 그 경쟁관계를 파악하여 플럭의 크기의 증감을 예측할 수 있게 농도(?)와 난류소산매개변수(?)를 이용하여 $c/G^{0.5}$로 매개화하였다. 실험 결과, 순방향 흐름을 제외하고 스토크스파 흐름 조건을 이용하여 진행된 모의에서는 플럭의 크기와 농도가 반비례하는 현상을 관찰할 수 없었으며 $c/G^{0.5}$ 의 변화 역시 흐름의 속도와 농도가 더 큰 지점에서 큰 값을 가지는 일반적인 결과를 나타내었다. 그러나 같은 조건에서 순방향흐름을 추가하여 모의한 결과에서는 플럭의 크기와 농도가 반비례하는 현상을 나타냈다. 연직 방향 $c/G^{0.5}$의 변화를 나타낸 그래프에서 응집과 파괴의 우세에 따라 $c/G^{0.5}$ 가 역전되는 현상을 확인하였다. 즉, 플럭의 크기는 난류의 구조와 그 영향에 의해 농도와 비례관계를 갖지 않을 수도 있다고 판단된다. 또한 본 연구에서 정상류 흐름 조건의 유무에 따라 플럭의 크기와 농도가 비례하거나 반비례하는 상반된 결과를 보였다. 정상류 흐름 조건이 난류의 강도에 큰 역할을 하며 이에 따라 비선형 관계에 영향을 끼친다는 것을 발견하였다. 그러나 흐름의 영향에 대한 더 자세한 분석은 본 연구에서 진행되지 않았으며 향후 연구 시에 분명히 고려되어야 할 사항이다.

• Journal of the Korea institute for structural maintenance and inspection
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• v.28 no.1
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• pp.98-106
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• 2024

Due to advancements in construction technology and analytical tools, an increasing number of cable-stayed bridges have been designed and constructed in recent years. A cable is a structural element that primarily transmits the main load of a cable-stayed bridge and plays the most crucial role in reflecting the overall condition of the entire bridge system. In this study, a vision-based method was applied to estimate the tension of the stay cables located at a long distance. To measure the response of a cable using a vision-based method, it is necessary to install feature points or targets on the cable. However, depending on the location of the point to be measured, there may be no feature points in the cable, and there may also be limitations in installing the target on the cable. Hence, it is necessary to find a way to measure cable response that overcomes the limitations of existing vision-based methods. This study proposes a method for measuring cable responses by utilizing the characteristics of cable shape. The proposed method involved extracting the cable shape from the acquired image and determining the center of the extracted cable shape to measure the cable response. The extracted natural frequencies of the vibration mode were obtained using the measured responses, and the tension was estimated by applying them to the vibration method. To verify the reliability of the vision-based method, cable images were obtained from the Hwatae Bridge in service under ambient vibration conditions. The reliability of the method proposed in this study was confirmed by applying it to the vibration method using a vision-based approach, resulting in estimated tensions with an error of less than 1% compared to tensions estimated using an accelerometer.

• Information Systems Review
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• v.21 no.4
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• pp.175-195
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• 2019

This study conducted both big data and netnography analysis to analyze consumer needs and behaviors of online consumer community. Big data analysis is easy to identify correlations, but causality is difficult to identify. To overcome this limitation, we used netnography analysis together. The netnography methodology is excellent for context grasping. However, there is a limit in that it is time and costly to analyze a large amount of data accumulated for a long time. Therefore, in this study, we searched for patterns of overall data through big data analysis and discovered outliers that require netnography analysis, and then performed netnography analysis only before and after outliers. As a result of analysis, the cause of the phenomenon shown through big data analysis could be explained through netnography analysis. In addition, it was able to identify the internal structural changes of the community, which are not easily revealed by big data analysis. Therefore, this study was able to effectively explain much of online consumer behavior that was difficult to understand as well as contextual semantics from the unstructured data missed by big data. The big data-netnography integrated model proposed in this study can be used as a good tool to discover new consumer needs in the online environment.