• Journal of Korean Society of Environmental Engineers
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• v.35 no.6
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• pp.430-435
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• 2013

A seasonal variation of phytoplankton community in the middle-lower part of the Nakdong River was studied in four sampling stations at monthly intervals from January to December 2012. We identified 40 genera 72 species of phytoplankton. Among these, diatoms were 36 species (50.0%), green algae 20 species (27.8%), blue-green algae 9 species (12.5%) and others 7 species (9.7%), respectively. The phytoplankton standing crops were recorded a maximum of 29,640 cells/mL at the Mulgeum (St. 4) in June and a minimum of 236 cells/mL at the Goryung (St. 1) in October. Also, Standing crops were increased with proceeding from middle part to lower part. Ecological important species were Stephanodiscus hantzschii, Cyclotella meneghiniana, Synedra acus, Aulacoseira granulata, Pediastrum sp. and Microcystis aeruginosa. Seasonal succession of phytoplankton represented that Stephanodiscus hantzschii was dominant species in winter, Cyclotella meneghiniana, Synedra acus was dominant species in spring, Microcystis aeruginosa, Cyclotella meneghiniana, Fragilaria crotonensis, Synedra acus, Aulacoseria granulata was dominant species in summer, and Aulacoseria granulata, Cyclotella meneghiniana, Fragilaria crotonensis was dominant species in autumn. In the community analysis, diversity index and dominant index were higher May~July and December~February, respectively. Also, diversity index and dominant index were decreased and increased with proceeding from middle part to lower part.

• Korean Journal of Ecology and Environment
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• v.42 no.2
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• pp.183-191
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• 2009

This study was to evaluate ecological health of Dongjin River in October 2007. The ecological health assessments was based on the Index of Biological Integrity (IBI), Qualitative Habitat Evaluation Index (QHEI), and water chemistry. For the study, the models of IBI and QHEI were modified as 8 and 11 metric attributes, respectively. We also analyzed spatial patterns of chemical water quality over the period of 2005${\sim}$2008, using the water chemistry dataset, obtained from the Ministry of Environment, Korea. In Dongjin River, values of IBI averaged 19 (n=3), which is judged as a "Fair" condition after the criteria of Barbour et al. (1999). There was a distinct spatial variation. IBI score at Site 1 was estimated as 28, indicating a "Good" condition whereas, IBI at Site 2 and Site 3 were as 18 and 12, indicating "Fair" and "Poor" condition, respectively. Habitat analysis showed that QHEI values in the river averaged 117 (n=3), indicating a "Fair${\sim}$Good" condition after the criteria of Barbour et al. (1999). Values of BOD and COD averaged 2.3 mg $L^{-1}$ (scope: 0.1${\sim}$8.9 mg $L^{-1}$) and 5.5 mg $L^{-1}$ (scope: 1.8${\sim}$12.6 mg $L^{-1}$), respectively during the study. Total nitrogen (TN) and total phosphorus (TP) averaged 2.7mg $L^{-1}$ and 0.127mg $L^{-1}$, respectively, and the nutrients showed large longitudinal gradients between the upper and lower reach. Overall, dataset of IBI, QHEI, and water chemistry showed that river health was a gradual decline at upstream to downstream. So, Dongjin River should be protected from habitat disturbance and chemical pollutions.

• Korean Journal of Environment and Ecology
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• v.18 no.2
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• pp.158-166
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• 2004

For the zoning of natural ecosystem, Vegetation Index is calculated from the vegetation data surveyed on Baekdudaegan (from Namdeogyusan to Sosagogae). Five factors-biodiversity, conservation value of the stand, environmental quality, longevity of the stand, site productivity- are considered in the calculation of Vegetation Index. Vegetation Index might be a useful zoning tool for management of Baekdudaegan. For Vegetation Index I, 8 sample plots 12.l％ of total 66 sample plots are belong to core area, 21 sample plots 31.8％ and 37 sample plots 56.l％ are belong to buffer zone and transition area, respectively. For Vegetation Index II, 37 sample plots 41.9% of total 60 sample plots are belong to core area, 19 sample plots 28.8％ and 19 sample plots 28.8% are belong to buffer zone and transition area, respectively.

• The Journal of the Korea Contents Association
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• v.21 no.8
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• pp.640-650
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• 2021

The purpose of this study was to identify factors affecting the Quality of Life of Ankylosing Spondylitis Patients Based on Korean Bath Ankylosing Spondylitis Disease Activity Index (KBASDAI) and Korean Bath Ankylosing Spondylitis Functional Index (KBASFI). The subjects of this study were 19 years of age or older who were diagnosed with ankylosing spondylitis(AS). Data was collected through an online survey. A univariate analysis of differences in quality of life according to variable characteristics was performed, and multiple regression analysis was performed to examine factors affecting quality of life. As a result of regression analysis, the higher the KBASFI (𝛽=0.622, p<0.001) and the KBASDAI (𝛽=0.180, p=0.032) scores, and the lower the average monthly household income(𝛽= 0.186, p=0.001), the worse the quality of life. In order to improve the quality of life of AS patients, intervention studies that can lower disease activity and improve function are needed.

• Journal of the Korean Geotechnical Society
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• v.29 no.1
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• pp.23-27
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• 2013

The risks of debris flows caused by climate change have increased significantly around the world. Recently, landslide disaster prevention technology is more focused on the failure and post-failure dynamics to mitigate the hazards in flow-prone area. In particular, we should define the soil strength and flow characteristics to estimate the debris flow mobility in the mountainous regions in Korea. To do so, we selected known ancient landslides area: Inje, Pohang and Sangju debris flows. Firstly we measured physical and mechanical properties: liquidity index and undrained shear strength by fall cone penetrometer. From the test results, we found that there is a possible relationship between liquidity index and undrained shear strength, $C_{ur}=(1.2/I_L)^{3.3}$, in the selected areas, even though they were different in geological compositions. Assuming that the yield stress is equal to the undrained shear strength at the initiation of sliding, we examined the flow characteristics of weathered soils in Korea. When liquidity index is given as 1, 1.5 and 3.0, the debris flow motion of weathered soils is compared with that of mud-rich sediments, which are known as low-activity clays. At $I_L=1$, it seems that debris flow could reach approximately 250m after 5 minutes. As liquidity index increased from 1 to 3, the debris flow propagation of weathered soils is twice than that of low-activity clays. It may be due to the fact that soil masses mixed with the ambient water and then highly fragmented during flow, thereby leading to the high mobility. The results may help to predict the debris flow propagation and to develop disaster prevention technology at similar geological settings, especially for the weathered soils, in Korea.

• Journal of Korean Society of Forest Science
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• v.107 no.2
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• pp.193-204
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• 2018

This study was carried out to select the optimal method of competition index computation according to the competitor selection methods and distant-dependent competition index models, and to analyze the characteristics of competition indices in terms of thinning intensity and tree density targeting Pinus densiflora, Pinus koraiensis, and Larix kaempferi, which are the major coniferous species in Korea. Data was the re-investigated tree information from 240 permanent plots of 80 sites in the stands of P. densiflora, P. koraiensis, and L. kaempferi, which were located in the national forest of Gangwon and North Gyeongsang provinces. The number of subject trees with competition index calculated were 1126 trees for P. densiflora, 4093 trees for P. koraiensis, and 3399 trees for L. kaempferi. For the best competition index computation method, three kinds of competitor selection methods were considered: basal area factor, angle of height, angle of height to crown base. Also, six kinds of competition index models were compared: Lorimer, Martin-EK, Braathe, Heygi, Daniels, and Modified Daniels, which was developed in this study. Correlation coefficient was the best when the competitor selection method of basal area factor $4m^2/ha$ and the competition index model of Modified Daniels were used, and thus, it was selected as the best method for computing competition index. According to the best method by stand characteristics, competition index decreased in all species as thinning intensity was high and tree density was low.

• Journal of Soil and Groundwater Environment
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• v.7 no.4
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• pp.59-67
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• 2002

As a parameter for hydrodynamic modeling to define the range of seawater intrusion, dispersivities are frequently determined from pre-experiments or theoretical studies because field experiments need a lot of time and expenses. If the dispersivities are inadequate for an aquifer, the numerical results may have some errors. We examined the validity of longitudinal dispersivities by comparing the ranges of seawater intrusion with numerical modeling, field data and apparent resistivity sections. In the numerical modeling the TDS distributions simulated by the Xu's longitudinal dispersivity are more similar to the values of TDS measured at monitoring wet]s and boreholes than those by the Neuman's longitudinal dispersivity. The ranges of seawater intrusion by numerical simulations using Xu's longitudinal dispersivity show that the contour line of 1000 ㎎/L. as TDS is located at 480 m from the coast in May, while at 390 m in July. The difference is originated from the shift of the interface between seawater and fresh water. It moved toward the coast in July because of the seasonal increase of hydraulic gradient according to rainfall. A contour line of 15 ohm-m was used to define the range of seawater intrusion in apparent resistivity sections. From this criterion on the interface between seawater and fresh water, the range of seawater intrusion is located at 450 m from the coast. This result is similar to the range of seawater intrusion simulated by the numerical modeling using Xu's dispersivity. Therefore the range of seawater intrusion shows the difference due to the dispersivities used for the hydrodynamic modeling and the dispersivity generated by the Xu's equation is considered more effective to decide the range of seawater intrusion in this study area.

• Journal of Korea Water Resources Association
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• v.52 no.2
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• pp.149-161
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• 2019

In this study, the effect of the fluid flow characteristics on the length distribution of the fracture elements composing the fracture network is analyzed numerically using the 3D fracture crack network model. The truncated power-law distribution is applied to generate the length distribution of the fracture elements and the simulations of fluid flow are carried out with the exponent ${\beta}_l$ from 1.0 to 6.0. As a result of simulations, when the exponent ${\beta}_l$ increases, the length distribution of the fracture elements gradually decreases, and the connectivity between the fracture elements affecting the permeability of the fracture network becomes weak. When we analyzed the distributions of flow rate calculated at each fracture element with the exponent ${\beta}_l$, the mean flow rate at ${\beta}_l=1.0$ was estimated to be about 447 times larger than that at ${\beta}_l=6.0$ and for the flow calculated at the outflow boundary of the fracture network, the case of ${\beta}_l=1.0$ was estimated to be 6,440 times larger than that of ${\beta}_l=6.0$.

• Proceedings of the Optical Society of Korea Conference
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• 2003.02a
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• pp.140-141
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• 2003

광섬유 통신에서 넓은 대역폭 증폭을 이루기 위하여 광대역 증폭기가 필요하다. 증폭기의 대역폭을 넓히기 위해 C-대역과 L-대역 EDFA를 결합하여 사용하는 등의 여러 가지 방법이 제안되고 있다. 그 중 L-대역을 결합하는 방법이 실제 시스템 적용에서 가장 즉시 이용가능한 방법이라 할 수 있다. L-대역 EDFA의 경우 상대적으로 이득이 낮으며 효율이 떨어진다. 이득이나 효율을 높이기 위해서 FBG, 양방향 펌핑(bidirectional pump), 그리고 이중경로(double-pass) 구조를 이용하는 방법이 제안되었다. (중략)

• Food Industry And Nutrition
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• v.7 no.2
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• pp.45-50
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• 2002

본 연구는 성인 남자의 식생활 형태가 혈중지질 농도에 미치는 영향을 연구하기 위한 기초적인 연구로 영남의료원의 건강피검진자를 대상으로 식습관, 영양소 섭취량, 혈중지질농도를 조사하였다. 전체 조사대상자 220명중에 정상인 133명(60.5%), 경계수준군과 고콜레스테롤환자군은 각각 62명(28.2%)과 25(11.3%)를 차지하였다. 조사대상의 평균연령은 $48.4\pm9.5$세이었고, 체중은 $67.7\pm10.2kg$이었다. 평균 Broca's 지수(RBM)와 체질량지수(BMI)는 각각 $109\pm14.3$, $23.6\pm3.0$이었다. 식습관이 좋은 사람이 12명(5.4%)이고 보통인 사람이 130명(59.1%)에 해당하였으며 나쁜 사람이 78명(35.5%)으로 나타났으며, 식사형태와 식품의 배합에 대한 인식이 부족한 것으로 나타났다. 조사대상자의 혈중 중성지질의 평균농도는 약 115.8mg/dL이었고, $90\sim120mg/dL$인 사람이 대상자 220명중에 131명으로 전체의 59.9%를 차지하였다. 조사 대상자의 혈중 콜레스테롤 농도의 평균은 192.4mg/dL이었고, 혈중 콜레스테롤의 농도에 따른 대상자의 분포는 $180\sim210mg/dL$인 대상자가 73명으로 전체의 33.2%를 차지하여 가장 많았고 $150\sim210mg/dL$사이 포함되는 사람이 전체의 60.5%로 133명인 것으로 나타났다.