• 한국조경학회지
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• 제28권4호
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• pp.117-124
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• 2000

This paper presents a design of urban waterfront park using agricultural reservoir in urban fringe area to meet increasing leisure demand for urban resident and to improve resident's quality of life through preventing the reservoir from urban use after reclamation. The site, Unam-Ji, is located on northern part of Taegu metropolitan area, having 17,791 square meters. We had designed this park from 1997 to 1998. After analyzed such factor as accessibility, current land uses, topography, hydrology, vegetation and landscape, climate, and soil, we constructed basic design scheme and principes such as conservation of natural resources, meeting user's recreation demands, providing opportunities for experiencing natural process, integrating naturalness and amenity of the site, and comfortable place with natural dynamism. Based on these principles, we have designed Unam-Ji waterfront park having intrinsic characteristics of the site, maintaining water quality and ecological restoration and improving water-based recreation opportunities. After evaluation of such criteria of design alternative as land use and circulation, spatial organization, convenience for use of and maintenance, conservation of natural environment, and degree of achieving planning and design goals, and maintaining landscape, we have visualized and formalized waterfront park in design process, which is consisted of four squares-- green square for multiple uses, water-based recreation square, pedestrian roads and decks near waterfront, performance square and fords near waterfront. In conclusion, this waterfront park design contributes to improve quality of urban development through preserving agricultural as an important component of urban water system and provide important planning and design implications in urban open space planning.

• 대한조선학회 특별논문집
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• 대한조선학회 2005년도 특별논문집
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• pp.216-221
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• 2005

Many tanks such as a fresh water tank, an aft peak tank and oil tanks are arranged in the engine room and aft part areas of the ship. By added mass effect of the fluid inside the tanks, the natural frequency will be changed according to filling height of the tank. For this reason, there is possibility of occurrence of excessive vibration by resonance between natural frequencies of local structure and excitation frequencies of the propeller or main engine. Therefore, calculation of natural frequencies is required for structure for many types of tank which are contacting with water or oil to consider added mass effect for anti-resonance design at design stage. In this study, a case of structure damage on the fresh water tank for 2600 TEU container vessel is introduced. In addition, natural frequency analysis and vibration measurement have been performed to investigate vibration characteristics for excessive vibration control.

• 한국환경보건학회지
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• 제45권6호
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• pp.561-568
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• 2019

Objectives: The most commonly detected heavy metals in rocks and soils, including Pb, Cd, Cu, Fe, Mn and As, are representative pollutants discharged from abandoned mines and have been listed as potential sources of contamination in drinking water. This study focused on increasing the removal efficiency of heavy metals from drinking water resources by surface modification of natural adsorbents to reduce potential health risks. Methods: Iron oxide coating and graft polymerization with zeolites and talc was conducted for bipolar surface modification to increase the combining capacity of heavy metals for their removal from water. The removal efficiency of heavy metals was measured before and after the surface modification. Results: The removal efficiency of Pb, Cu, and Cd by surface modified zeolite showed 100, 92, and 61.5%, respectively, increases compared to 64, 64, and 38% for non-modified zeolite. This implies that bipolar surface modified natural adsorbents have a good potential use in heavy metal removal. The more interesting finding is the removal increase for As, which has both cation and anion characteristics showing 27% removal efficiency where as non-modified zeolite showed only 2% removal. Conclusions: Zeolite is one of the most widely used adsorptive materials in water treatment processes and bipolar surface modification of zeolite increases its applicability in the removal of heavy metals, especially As.

• Environmental Engineering Research
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• 제13권3호
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• pp.107-111
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• 2008

Water quality contamination issues are of critical concern to human health, whilst pesticide release generated from irrigated land should be considered for protecting natural habitats and human health. This paper suggests new method for evaluation and analysis using the GIS technique based on integrated spatial modeling framework. The pesticide use on irrigated land is a subset of the larger spectrum of industrial chemicals used in modern society. The behavior of a pesticide is affected by the natural affinity of the chemical for one of four environmental compartments; solid matter, liquid, gaseous form, and biota. However, the major movements are a physical transport over the ground surface by rainfall-runoff and irrigation-runoff. The irrigated water carries out with the transporting sediments and makes contaminated water by pesticide. This paper focuses on risk impact identification and assessment using GIS technique. Also, generated data on pesticide residues on farmland and surface water through GIS simulation will be reflected to environmental research programs. Finally, this study indicates that GIS application is a beneficial tool for spatial pesticide impact analysis as well as environmental risk assessment.

• Fisheries and Aquatic Sciences
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• 제26권4호
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• pp.282-293
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• 2023

Nile perch and Nile tilapia are major commercial species in Uganda, and thus require continuous production. However, their production is impacted by anthropogenic activities such as fishing in breeding habitats. The aim of this study was to identify and characterize Nile perch and Nile tilapia fish breeding habitats on Lake Kyoga. Water quality, lake bottom, fish and vegetation type samples were collected from 20 sites in April of 2021 and 2022. Key informant interviews were conducted with experienced fishermen at five fish landing sites. The water quality parameters indicated significant difference within the sites using analysis of variance. Sandy and muddy bottom types were equally spread at 40% each by use of a pie chart. Fish gonads showed no significant difference among the 20 sites. Bivariate correlation analysis of the vegetation types indicated a strong negative correlation with Nile perch while Nile tilapia had a positive correlation. Principal component analysis of the water quality, fish gonads and habitat vegetation components cumulatively contributed 82.5% in characterizing a fish breeding habitat. Four sites for Nile perch and four sites for Nile tilapia were characterized as breeding sites on Lake Kyoga and are recommended for mapping and gazettement as breeding habitats for sustainable fisheries management.

• Food Science and Biotechnology
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• 제16권5호
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• pp.691-709
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• 2007

Concerns on environmental waste problems caused by non-biodegradable petrochemical-based plastic packaging materials as well as consumer's demand for high quality food products has caused an increasing interest in developing biodegradable packaging materials using annually renewable natural biopolymers such as polysaccharides and proteins. However, inherent shortcomings of natural polymer-based packaging materials such as low mechanical properties and low water resistance are causing a major limitation for their industrial use. By the way, recent advent of nanocomposite technology rekindled interests on the use of natural biopolymers in the food packaging application. Polymer nanocomposites, especially natural biopolymer-layered silicate nanocomposites, exhibit markedly improved packaging properties due to their nanometer size dispersion. These improvements include increased mechanical strength, decreased gas permeability, and increased water resistance. Additionally, biologically active ingredients can be added to impart the desired functional properties to the resulting packaging materials. Consequently, natural biopolymer-based nanocomposite packaging materials with bio-functional properties have huge potential for application in the active food packaging industry. In this review, recent advances in the preparation and characterization of natural biopolymer-based nanocomposite films, and their potential use in food packaging applications are addressed.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2007년도 춘계학술대회B
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• pp.2626-2631
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• 2007

Air-water two phase natural circulation flow in the T-HERMES (Thermo-Hydraulic Evaluation of Reactor cooling Mechanism by External Self-induced flow)-1D experiment has been evaluated to verify and evaluate the experimental results by using the RELAP5/MOD3 computer code. The RELAP5 results have shown that an increase in the coolant inlet area leads to an increase in the water circulation mass flow rate. However, the water outlet area does not effective on the water circulation mass flow rate. As the coolant outlet moves to a lower position, the water circulation mass flow rate decreases. The water level is not effective on the water circulation mass flow rate. As the height increases in the air injection part, the void fraction increases. However, the void fraction in the upper part of the air injector maintains a constant value. An increase in the air injection mass flow rate leads to an increase in the local void fraction, but it is not effective on the local pressure.

• 분석과학
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• 제24권4호
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• pp.298-303
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• 2011

셀레늄은 인체의 필수영양소로써 환경에서 또한 많은 관심을 가지고 있는 원소이다. 셀레늄은 자연수에서 주로 +4가의 selenite ($SeO_3^{-2}$)와 +6가의 selenate ($SeO_4^{2-}$)로 용해되어 있는데, 이들의 독성 및 화학적 성질은 매우 다르다. 따라서 자연수에서 셀레늄의 거동을 이해하기 위해서는 이들 두 화학종을 분리하는 것이 필요하다. 기존에 알려진 알루미나 충전 컬럼과 이온크로마토그래피를 이용한 selenite와 selenate의 분리방법들은 silicate 때문에 자연수에 직접 적용하기가 곤란하였다. 따라서 마그네타이트가 용액의 pH에 따라 selenite와 selenate를 흡착하는 정도가 다르므로 마그네타이트가 충전된 컬럼을 이용하여 이들의 분리를 수행한 결과, 성공적으로 분리할 수 있었다. 아울러 자연수에 존재하는 다른 음이온들 중에서 silicate는 selenite의 흡착을 방해하므로 silicate의 농도를 고려하여 충분한 양의 마그네타이트를 사용하여야만 한다.

• The Korean Journal of Ecology
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• 제18권1호
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• pp.109-120
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• 1995

As the genetically modified microorganisms (GMMs) and their recombinant plasmid DNAs could be released into natural environments, their stabilities and impacts to indigenous microorganisls have become very importhant research subjects concerning with environmental and ecological aspects. In this study, the genetically modified E. coli CU103 and its recombinant pCU103 plasmid DNA, in which pcbCD genes involving in degradation of biphenyl and 4-chlorobiphenyl were cloned, were studied for their survival and stability in several different waters established under laboratory conditions. E. coli CU103 and its host E. coli XL1-Blue survived longer in sterile distilled water (SDW) and filtered autoclaved river water (FAW) than in filtered river water (FW). A lot of extracellular DNAs were released from E. coli CU103 by lytic action of phages in FW and the released DNAs were degraded by DNase dissolved in the water. Such effects of the factors in FW on stability of the recombinant pCU103 plasmid were also observed in the results of gel electrophoresis, quantitative analysis with bisbenzimide, and transformation assay. Therefore, the recombinant plasmids of pCU103 were found to be readily liberated from the genetically modified E. coli CU103 into waters by normal metabolic processes and lysis of cells. And the plasmid DNAs were quite stable in waters, but their stabilities could be affected by physicoKDICical and biological factors in non-sterile natural waters.

• 설비공학논문집
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• 제23권4호
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• pp.259-264
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• 2011

Gas hydrate is formed by physical binding between water molecule and gas such as methane, ethane, propane, or carbon dioxide, etc., which is captured in the cavities of water molecule under the specific temperature and pressure. $1\;m^3$ hydrate of pure methane can be decomposed to the methane gas of $172\;m^3$ and water of $0.8\;m^3$ at standard condition. If this characteristic of hydrate is reversely utilized, natural gas is fixed into water in the form of hydrate solid. Therefore, the hydrate is considered to be a great way to transport and store of natural gas in large quantity. Especially the transportation cost is known to be 18~25% less than the liquefied transportation. However, when methane gas hydrate is artificially formed, its reaction time may be too long and the gas consumption in water becomes relatively low, because the reaction rate between water and gas is low. Therefore, for the practical purpose in the application, the present investigation focuses on the rapid production of hydrates and the increment of the amount of captured gas by adding zeolite into pure water. The results show that when the zeolite of 0.01 wt% was added to distilled water, the amount of captured gas during the formation of methane hydrate was about 4.5 times higher than that in distilled water, and the methane hydrate formation time decreased at the same subcooling temperature.