• 한국물환경학회지
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• 제25권6호
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• pp.832-839
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• 2009

Since construction of the estuarine barrage at the mouth of the Nakdong River, eutrophication and increased abundance of phytoplankton have occurred mainly due to the increased retention time in the reach. However, during the spring, there is a decrease in chlorophyll-a, as a result of an increase in zooplankton number, which preys upon phytoplankton and affects the value of chlorophyll-a. In order to emphasize the importance of zooplankton data in water quality simulation, zooplankton community data were used to simulate water quality and eutrophication at Mulgeum located in 27 km upstream from the barrage. WASP 7.2 was used as the water quality model for the river, using a monthly data set from 2003 to 2005 for model calibration and verification. The results showed that chlorophyll-a, DO, and total nitrogen in the river were simulated well during the verification period. The results of water quality simulation using zooplankton community data in the model were better than those with phytoplankton death rate, in terms of the absolute value of percent bias, root mean square error, and Nash-Sutcliffe efficiency. Those results indicate the use of zooplankton data provides more accurate simulation results for chlorophyll-a and eutrophication.

• 한국지하수토양환경학회지:지하수토양환경
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• 제17권6호
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• pp.102-111
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• 2012

Fine suspended solids generated effluence from treatment process of mine drainage could destroy environment as the aesthetic landscapes, and depreciate water quality. Therefore, the purpose of this research is focused on process development applied the actual field for controlling fine suspended solids and heavy metals, and so lab-scale test was performed for inducement of basic data. The mine drainage used in this research was sampled in H mine located Jeongseon-gun, Gangwon-do. Concentration of suspended solid, arsenic, iron and manganese was exceeded the standard of contaminant limitation for the clean water, and particle size of suspended solid was less than 10 m as fine particle. Although hydraulic retention time of mine drainage for effective settling was required more than 6 hours, hydraulic retention time would be increased in winter season when the settling efficiency could be reduced because of viscosity decreasing. Moreover, installed inclination plate helped to increase settling efficiency of suspended solid about 48 %. Filtering media that was the most effective removal of suspended solids and heavy metal was decided granular activated carbon of 1~2 mm was the optimal size.

• 대한치과교정학회지
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• 제27권6호
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• pp.997-1004
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• 1997

골격성 III급 부정 교합은 동양에서 발생 빈도가 높으며 그 양상과 유형도 다양하며 치료가 까다로운 것으로 알려져 있다. 성장기 아동의 경우 조기에 골격 부조화를 발견하고 성장을 통해 골격의 부조화를 개선하여 수술의 가능성을 감소시키고 환자의 심리적 위축감을 감소시킬 수 있다면 그 치료는 매우 중요한 의미를 가질 것이다. 본 증례는 골격성 III급 부정교합 환자를 상악골 전방견인을 장치를 이용하여 비교적 짧은 전방 견인기간으로 안모의 개선을 얻을 수 있었던 임상적 증례이다. 비교적 어린 나이에 시도한 경우 에 더 짧은 전방견인 기간 동안에 만족할 만한 결과를 얻었으나 성장잠재력이 미약한 연령에서도 골격적 개선을 얻을 수 있었다. 그러나, 상악골 전방견인 장치의 효과에 대한 많은 선학들의 연구가 있었음에도 불구하고 아직 진단에 대한 criteria나 재발에 관한 연구는 매우 미약한 실정이고, 본 보고에서도 재발에 관한 관찰을 하지 못하였음이 아쉬움으로 남아있으며 향후에 본 증례들에 대한 retention과 relapse에 관하여 계속적인 관찰이 필요할 것이다.

• 한국물환경학회지
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• 제25권5호
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• pp.713-719
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• 2009

A natural wetland in the Nakdong River basin which effectively removes non-point source pollutants was investigated for 2 years to understand wetland topography, vegetation types, and water quality characteristics. The water depth of the natural wetland was in the range of 0.5~1.9 m which is suitable for the growth of non-emergent hydrophytes. The wetland has a high length to width ratio (3.3:1) and a relatively large wetland to watershed area ratio (0.057). A broad-crested weir at the outlet increases the retention time of the wetland whose hydrology is mainly dependent on storm events. The concentrations of dissolved oxygen in the growing season and the winter season showed anoxic and oxic conditions, respectively. Diurnal variations of DO and pH in the growing season were also observed due to weather change and submerged plants. COD and TP concentrations were low in the winter season due to low inflow rate and increased retention time. Increased TP concentrations in the spring season were caused by degradation of dead wetland plants. Nitrogen in the wetland was mostly in organic nitrogen form (>75%). During the growing season, ammonium concentration was high but nitrate nitrogen concentration was low, possibly due to anoxic and low pH conditions which are adverse conditions for ammonificaiton and nitrification. The results of this study can be used as preliminary data for design, operation, monitoring and management of a constructed wetland which is designed to treat diffuse pollutants in the Nakdong river watershed.

• 대한본초학회지
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• 제26권1호
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• pp.13-19
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• 2011

Objective : This study was to compare antioxidant activity and HPLC pattern analysis from 4 species of changpo(ch$\={a}$ngp$\'{u}$). Methods : To compare the antioxidant activity and HPLC pattern analysis from the 4 species of changpo, we performed the in vitro anti-oxidative activity assays and HPLC analysis from 70% ethanol extracts of Acorus gramineus Sol. (=AG), A. tatarinowii Schott (=AT), A. calamus L. (=AC) and Anemone altaica Fisch. ex C.A.Mey (=AA) taken in the herbal medicine market of Korea. Results : AG has the most effective anti-oxidative activity among 4 species of changpo. As the HPLC pattern analysis, AT was detected the unknown peak at retention time 14.9 min whereas AG was not showed any peak at the same retention time. These results suggest that AG could be used rather than AT when it need to be prescribed as anti-oxidative medicine. Conclusions : This result can be used as the basic data contributing to the stability of AG according to an appropriate clinical application.

• Applied Biological Chemistry
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• 제35권4호
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• pp.276-280
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• 1992

HPLC에 의한 카테킨류 5성분의 정량분석법을 검토한 결과, 종래의 이동상을 acetonitril, acetic acid 및 methanol 수용액에서 acetontrile, N,N-dimethyl formamide, ethyl acetate의 0.06% 인산수용액으로 전환하였을 때 컬럼에서의 용출시간을 45분에서 28분으로 줄일 수 있었으며, 특히 (-)-epigallocatechin-3-gallate(EGCG)나 (-)-epicatechin gallate(ECG)의 peak를 종래의 넓은 형태에서 예리한 chromatogram을 얻으므로써 분석값의 오차를 최소화 할 수 있었고 머므름시간$(0.32{\sim}3.97%)$이나 peak 면적$(1.61{\sim}7.02%)$의 변동계수도 신뢰할 수 있는 값을 얻었다. 또한 시판되고 있는 수종의 녹차류와 홍차 및 대만산 오룡차를 분석한 결과 녹차류의 카테킨 함량은 $120.3{\sim}153.7\;mg/g$ 이었고 홍차는 녹차류의 1/4수준 이었다.

• 정보저장시스템학회논문집
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• 제3권2호
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• pp.94-112
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• 2007

Nano-sized inverted domain dots in ferroelectric materials have potential application in ultrahigh-density rewritable data storage systems. Herein, a data storage system is presented based on scanning non-linear dielectric microscopy and a thin film of ferroelectric single-crystal lithium tantalite. Through domain engineering, we succeeded to form an smallest artificial nano-domain single dot of 5.1 nm in diameter and artificial nano-domain dot-array with a memory density of 10.1 Tbit/$inch^2$ and a bit spacing of 8.0 nm, representing the highest memory density for rewritable data storage reported to date. Sub-nanosecond (500psec) domain switching speed also has been achieved. Next, long term retention characteristic of data with inverted domain dots is investigated by conducting heat treatment test. Obtained life time of inverted dot with the radius of 50nm was 16.9 years at $80^{\circ}C$. Finally, actual information storage with low bit error and high memory density was performed. A bit error ratio of less than $1\times10^{-4}$ was achieved at an areal density of 258 Gbit/inch2. Moreover, actual information storage is demonstrated at a density of 1 Tbit/$inch^2$.

• 대한전자공학회논문지TE
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• 제39권4호
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• pp.335-340
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• 2002

본 논문에서 얇은 실리콘 산화막의 스트레스 유기 누설전류는 나노 구조를 갖는 트랜지스터의 ULSI 실현을 위하여 조사하였다. 인가전압의 온 오프 시간에 따른 스트레스전류와 전이전류는 실리콘 산화막에 고전압 스트레스 유기 트랩분포를 측정하기 위하여 사용하였다. 스트레스전류와 전이전류는 고스트레스 전압에 의해 발생된 트랩의 충방전과 양계면 가까이에 발생된 트랩의 터널링에 기인한다. 스트레스 유기 누설전류는 전기적으로 기록 및 소거를 실행하는 메모리 소자에서 데이터 유지 능력에 영향이 있음을 알았다. 스트레스전류, 전이전류 그리고 스트레스 유기 누설전류의 두께 의존성에 따른 산화막 전류는 게이트 면적이 10/sup －3/㎠인 113.4Å에서 814Å까지의 산화막 두께를 갖는 소자에서 측정하였다. 스트레스 유기 누설전류, 스트레스전류, 그리고 전이전류는 데이터 유지를 위한 산화막 두께의 한계에 대해 연구 조사하였다.

• The Journal of Asian Finance, Economics and Business
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• 제8권7호
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• pp.517-523
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• 2021

Audit quality encompasses the key elements that create an environment that maximizes the likelihood that quality audits are performed consistently. This study aimed to identify the impact of auditing quality on the market value of the manufacturing companies listed on the Amman Stock Exchange (ASE). The analytical method was adopted in this research to extract and collect the necessary data. This study hypothesizes that audit quality leads to an increase in the market value by the offering of high-quality services. The study used the panel data approach to analyze cross-sectional data for 41 industrial companies that included time series data for the period (2019-2019). To test its hypotheses, the study used the fixed-effect model. The study found that the audit quality factors (audit office size, client retention period, auditor's fees, and linking with international audit offices) did not have a significant impact on market value. It found also the positive impact of the audit office size on the market value of the listed companies on the ASE for the period from 2009 to 2019. The study recommended the management of the company realize the importance of contracting with audit offices of large size and good reputation because these offices are more capable of increasing their efficiency, qualifying their employees, and thus be fully prepared for the audit process efficiently and effectively.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제14권4호
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• pp.1562-1578
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• 2020

Vector data compression algorithm can meet requirements of different levels and scales by reducing the data amount of vector graphics, so as to reduce the transmission, processing time and storage overhead of data. In view of the fact that large threshold leading to comparatively large error in Douglas-Peucker vector data compression algorithm, which has difficulty in maintaining the uncertainty of shape features and threshold selection, a segmented Douglas-Peucker algorithm based on node importance is proposed. Firstly, the algorithm uses the vertical chord ratio as the main feature to detect and extract the critical points with large contribution to the shape of the curve, so as to ensure its basic shape. Then, combined with the radial distance constraint, it selects the maximum point as the critical point, and introduces the threshold related to the scale to merge and adjust the critical points, so as to realize local feature extraction between two critical points to meet the requirements in accuracy. Finally, through a large number of different vector data sets, the improved algorithm is analyzed and evaluated from qualitative and quantitative aspects. Experimental results indicate that the improved vector data compression algorithm is better than Douglas-Peucker algorithm in shape retention, compression error, results simplification and time efficiency.