• Journal of Korean Society on Water Environment
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• v.25 no.6
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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.

• Journal of Soil and Groundwater Environment
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• v.17 no.6
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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.

• The korean journal of orthodontics
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• v.27 no.6 s.65
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• pp.997-1004
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• 1997

The clinical cases presented here involve skeletal Class III malocclusion cases treated with maxillary protraction in a relatively short period of time with good results. When used on young patients, satisfactory results were obtained in a short period of time, but even for those with less growth potential remaining, skeletal enhancement was still evident. However, data on the criteria of diagnosis or relapse following maxillary protraction is limited despite the number of studies on the subject. The present study could not include the observations on retention and relapse, and further studies in the future nay include such observations.

• Journal of Korean Society on Water Environment
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• v.25 no.5
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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.

• The Korea Journal of Herbology
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• v.26 no.1
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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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• v.35 no.4
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• pp.276-280
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• 1992

Quantutative analysis of catechins by HPLC was studied. When the mobile phase was switched from the conventional(AOAC) Methanol, Acetonitril and Acetic acid solution in $H_2O$ to 0.06% Phosphate solution with Acetonitrile, N,N-Dimethyl formamide, and Ethyl acetate, retention time could be reduced from 45 min to 28 min, especially, we obtained sharper chromatogram of the compounds, either (-)EGCG or (-)ECG, which resulted in minimization of analytical erros. CVs of retention time $(0.32{\sim}3.97%)$ and peak area $(1.61{\sim}7.01%)$ indicated that the data were more reliable. Content of catechins in commerical teas analyzed by the method was $120.3{\sim}153.7\;mg/g$ in green teas which was about 4 times that in black tea.

• Transactions of the Society of Information Storage Systems
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• v.3 no.2
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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/$inch^2$.

• Journal of the Institute of Electronics Engineers of Korea TE
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• v.39 no.4
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• pp.335-340
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• 2002

In this paper, the stress induced leakage currents of thin silicon oxides is investigated in the ULSI implementation with nano structure transistors. The stress and transient currents associated with the on and off time of applied voltage were used to measure the distribution of high voltage stress induced traps in thin silicon oxide films. The stress and transient currents were due to the charging and discharging of traps generated by high stress voltage in the silicon oxides. The transient current was caused by the tunnel charging and discharging of the stress generated traps nearby two interfaces. The stress induced leakage current will affect data retention in electrically erasable programmable read only memories. The oxide current for the thickness dependence of stress current, transient current, and stress induced leakage currents has been measured in oxides with thicknesses between 113.4${\AA}$ and 814${\AA}$, which have the gate area $10^3cm^2$. The stress induced leakage currents will affect data retention and the stress current, transient current is used to estimate to fundamental limitations on oxide thicknesses.

• The Journal of Asian Finance, Economics and Business
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• v.8 no.7
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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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• v.14 no.4
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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.