• Journal of Broadcast Engineering
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• v.2 no.2
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• pp.104-113
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• 1997

In this paper, we investigate on the techniques for still image compression based on the wavelet transform, which will be adopted as a part of the MPEG-4 compression standards. Also we propose an effective still image compression technique, which is simpler than the MPEG-4 compression method and is improved by using a visually weighted quantizer based to HVS(Human Visual System), Simulations are carried out and compared with the algorithm proposed in MPEG-4. The simulation results show that the proposed method in this paper gives much better image quality than that of the method in MPEG-4. Also, except the case where the compression ratio is high, it shows that the proposed method has lower in complexity and provides a better subjective and objective image quality than EZW in most cases. Since wavelet transform well reflects HVS, the compressed image rarely causes blocking artifact compared with JPEG, and in most cases, it shows considerable quality improvement over JPEG.

• Applied Chemistry for Engineering
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• v.31 no.6
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• pp.603-606
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• 2020

A hydrophilic alkaline room temperature ionic liquid electrolyte (RT-IL) carrying hydroxide ion as an anion and 1-benzyl-3-butylimidazolium as a cation was synthesized. Electrochemical, physical and structural properties of the synthesized RT-IL were characterized using cyclic voltammetry, ionic conductivity, viscosity, thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), FT-IR, and 1H-NMR measurements. High ionic conductivity and low viscosity characteristics comparable to 0.1 M KCl electrolyte solution were achieved for the RT-IL in addition to a wide electrochemical potential window of about 4.4 V. The results indicate that the RT-IL is promising for future applications as an alternative electrolyte to energy and environmental research fields.

• Prospectives of Industrial Chemistry
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• v.22 no.5
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• pp.25-40
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• 2019

전 세계적으로 환경문제를 해결하기 위한 방안으로 환경규제를 강화시키며 특히 다양한 대기오염 물질 중 최근 큰 이슈인 초미세먼지 저감을 위해 전구물질로 알려진 질소산화물을 제어하기 위한 다양한 기술개발이 가속화되고 있다. 특히, 다양한 처리기술 중에 기술적·경제적인 이점을 갖춘 선택적 촉매환원법(selective catalytic reduction, SCR) 기술을 통하여 질소산화물 제거를 위해 암모니아를 환원제로 반응에 참여시켜 인체에 무해한 H₂O, N₂로 전환하는 기술이 대표적이다. 최근 전 세계적으로 다양한 산업군에서 질소산화물이 배출되고 있으며, 점오염원뿐만이 아니라 비점오염원(mobile sources)에 대한 규제가 강화되고 있다. 디젤엔진이 장착된 선박 배가스 처리장치 내 SCR 기술이 주목을 받고 있으며, NH₃-SCR에 사용되는 촉매는 주로 VO_x/TiO₂, VO_x/W/TiO₂ 촉매가 대표적이다. 한편 선박 디젤엔진에 사용되는 연료에 따라 연소배가스 특성이 다르다. 이러한 연료가 연소됨에 따라 SO₂, SO₃가 발생되고 환원제인 NH₃와 결합하여 황산암모늄염((NH₄)₂SO₄), ABS (ammonium bisulfate, NH₄HSO₄)과 같은 염을 형성시켜 탈질촉매의 비활성화 문제가 발생된다. 이러한 비활성화 물질이 침적된 탈질촉매를 재활성화 시키기 위하여 열 산화를 통해 재생시키고 있다. 이처럼 선박용 SCR 촉매는 강화되는 배출규제 및 엔진기술의 발달로 저감되는 운전 온도에 대비하여 저온 활성 재생이 가능한 고활성, 고내구성 촉매기술 개발이 필요하다.

• New & Renewable Energy
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• v.20 no.2
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• pp.44-54
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• 2024

The objective of this study was to contribute to domestic offshore wind farms by reasonably predicting the expected completion time and installed power generation capacity of offshore wind projects in South Korea. Offshore wind power is drastically regarded as a core tool for clean energy transition and industrial decarbonization in the fight against the climate crisis globally. Especially in South Korea offshore wind power is the main tool in partaking in RE100 and K-RE100, and the Korean government aims to install 14.9 GW of offshore wind farms by 2030. However, this seems to have been significantly delayed due to the complex process of obtaining permits for offshore wind power in Korea. Thus, a reasonable prediction of power generation and a timeline for the final construction are imperative. To establish the delay time for permit licenses, classified location factors were included into site analysis. These factors comprised reviews of transmission and military operability, environmental impact assessment, maritime traffic safety examination, wind resource assessment and an analysis of current offshore wind projects. According to the analysis, the majority of offshore wind projects currently being developed in Korea are predicted to be delayed by 3-5 years as they are among the criteria included in key discussion points for obtaining permits. The cumulative installed power capacity and annual power generation after construction are expected to be 37 GW and 97 TWh respectively.

• Journal of the Korean Society of Radiology
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• v.85 no.2
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• pp.270-296
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• 2024

Coronary CT angiography (CCTA) is recognized for its role as a gatekeeper for invasive coronary angiography in patients suspected of coronary artery disease because it can detect significant coronary stenosis with high accuracy. However, heavy plaque in the coronary artery makes it difficult to visualize the lumen, which can lead to errors in the interpretation of the CCTA results. This is primarily due to the limited spatial resolution of CT scanners, resulting in blooming artifacts caused by calcium. However, coronary stenosis with high calcium scores often requires evaluation using CCTA. Technological methods to overcome these limitations include the introduction of high-resolution CT scanners, the development of reconstruction techniques, and the subtraction technique. Methods to improve reading ability, such as the setting of appropriate window width and height, and evaluation of the position of calcified plaque and residual visibility of the lumen in cross-sectional images, are also recommended.

• The Korean Journal of Petroleum Geology
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• v.9 no.1_2 s.10
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• pp.24-39
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• 2001

Prospecting for energy and mineral resources is essential kind of public fundamentals that manage the nation's economy. Most explorations in the past were concentrated in the simple structural traps in relatively shallow depth. Due to their vast exploitation, recent history has shown that the emphasis in explorations has steadily shifted toward the subtle stratigraphic traps in deeper level. Increasing exploration for the subtle stratigraphic traps in deeper level requires precise correlation and assessment of deeply buried strata in the basin. However, the descriptive stratigraphic principles used for evaluation of the simple structural traps are limited to delineate the subtle stratigraphic traps in deeper depth. As this occurs, it is imperative to establish a new stratigrtaphic paradigm that allows a more sophisticated understanding on the basin stratigraphy. This study provides an exemplary application of integrated stratigraphic approach to defining basin stratigraphy of the Middle Ordovician Taebacksan Basin and the Cretaceous South Yellow Sea Basin, Korea. The integrated stratigraphic approach gives much better insight to unravel the stratigraphic response to tectonic evolution of the basins, which can be utilized for enhancing the efficiency of resources exploration and development in the basins. Thus, the integrated stratigraphic approach should be considered as a new stratigraphic norm that can improve the probability of success in any type of resources exploration and development project.

• Korean Security Journal
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• no.31
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• pp.125-155
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• 2012

Terrorist organization has shown the trend of secret organization and it is harder to cope with terrorism because of uncertainty of terrorism. Homegrown terrorism is the one, whose preparation, execution and effect are restricted to domestic area. By the way, in the worldwide economic depression, violence and radical demonstration have shown the expansion trends as in Middle East, political revolution of Africa, anti-social resistance of Europe and Wall Street Occupation of USA. Homegrown terrorism is occurring in various countries such as UK and Spain as well as USA. Specialists warn homegrown terrorism in Korea. The purpose of this study was to prospect the possibility of homegrown terrorism that can be generated in the transfer to multi-culture society as various foreigners come to Korea rapidly and suggest the method to cope with the trend. The study analyzed environment and analysis of homegrown terrorism that Korea faces now. The methods to cope with homegrown terrorism are as follows. First, distribution of radical homegrown terrorism via internet should be prevented. Second, the connection between terrorist organization and homegrown terrorist should be prevented. Third, there should be a cooperation among government, residents and religious group. Fourth, there should be an open approach against multi-culture society. Fifth, there should be a systematic control for cause of new conflict. Finally, there should be a long-term approach to cause of new conflict. If we do not make an effort to prevent homegrown terrorism, terrorism environment may face new aspect and national and social cost for it will increase.

• Journal of the Korean Chemical Society
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• v.19 no.3
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• pp.174-178
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• 1975

The intermediate, 17${\alpha}$-methyl-4-aza-5${\alpha}$-androstan-17${\beta}$-ol(Ⅸ) required for the synthesis of 4-(${\beta}$-guanidinoethyl)-17${\alpha}$-methyl-4-aza-5${\alpha}$-androstan-17${\beta}$-ol(V) was obtained through a reaction of 17${\alpha}$-methyl-3,5-seco-4-norandrostan-17${\beta}$-ol-5-on-3-oic acid(VI) with ammonium hydroxide followed by two reductions(platinum dioxide with hydrogen and lithium aluminium hydride). Condensation of Ⅸ with chloroacetonitrile under anhydrous condition, followed by reduction of the nitrile with lithium aluminium hydride gave 4-(${\beta}$-aminoethyl)-17${\alpha}$-methyl-4-aza-5${\alpha}$-androstan-17${\beta}$-ol(XI). The reaction of XI with 2-methyl-2-thiopseudourea or 3,5-dimethylpyrazole-1-carboxamidine, or cyanamide provided the title compound, V. Relaxation of the nictitating membrane, in the absence of mydriasis, is considered to be evidence of adrenergic neurone blockade. Thus the test compound(V) resembles that of the classical adrenergic neurone blocking agents.