• Journal of Korean Society of Environmental Engineers
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• v.29 no.12
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• pp.1337-1344
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• 2007

In this research, we synthesized potassium ferrate(VI) acting as an oxidant, disinfectant, and coagulant, and used it to treat natural organic matter(NOM, HA and FA) in river water. The removal efficiencies obtained by $UV_{254}$ ranged from 20.7 to 73.6% for 10 mg/L HA and from 52.6 to 77.5% for 10 mg/L FA in Nakdong river sample as the ferrate dose varied from 2 to 46 mg/L(as Fe). However, the removal efficiencies by TOC analysis ranged from 0 to 20.3% for HA and from 0 to 26.6% for FA at the same ferrate doses. The removal efficiencies of NOM increased either with decreasing pH or with increasing temperature. The removal efficiency of HA by ferrate was comparable to those by traditional coagulants such as $Al_2(SO_4)_3{\cdot}18H_2O$, $FeSO_4{\cdot}7H_2O$, and FeO(OH). The reaction between ferrate and HA reached a steady state within 60 seconds, showing first-order with respect to the reaction time. The removal efficiencies of HA by traditional coagulants were improved by pretreatment of HA using a small amount of ferrate.

• The Korean Journal of Quaternary Research
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• v.17 no.2
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• pp.15-15
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• 2003

In South Korea, marine terraces have been well developed along the eastern coastal zone, and previous researches on the marine terraces have also been focused on to this coastal zone. The marine terraces of the eastern coast of South Korea had been classified into three terrace groups, that is, the higher, middle, and lower surface ones, according to the heights of marine terraces by previous studies(Oh, 1981 ;Chang, 1987 ;Yoon et. al, 1999, 2003 ; Hwang and Yoon, 1996 etc.). Recently, however, it tends to classify the marine terraces based on the concept of geomorphic surface units(Lee, 1987 ; Kim, 1990 ; Choi, S. 2003; Choi S. et. al 2003a,b, etc). For example, it was proposed that the marine terrace surfaces of Eupcheon coast of the southeastern coastal area of Korea could be classified into 16 geomorphic surfaces, i.e., Eupcheon 1terrace(former shoreline height of 160m), 2(153m), 3(140m), 4(130m), 5(124m), 6(115m), 7(100m), 8(92m), 9(82m), 10(71m), 11(62m), 12(53m), 13(43m), 14(35m), 15(18m) and 16(10m) surfaces, in descending order, according to the former shoreline heights(Choi, S, 2003 ; Choi, S. et. al, 2003a,b). Among these terraces, Eupcheon 1, 2, 4, 5 and 7 surfaces had not been reported in previous works. Among the above mentioned marine terraces, Eupcheon 15 terrace, the most widely and continuously distributed marine terrace have been identified as marine terrace of the Last Interglacial culmination period(oxygen isotope stage 5e) which was based on amino acid dates(124∼125ka BP) and geomorphological features such as red soil, pollen analysis, fossil cryogenic structures and crossing terrace concept. Eupoheon 15 terrace surfaces have also been proposed as the key surface for the identification and correlation of the so-called '5e' marine terrace in the eastern coast of South Korea. This terrace was reconfirmed as the Last Interglacial culmination period, which was based on the identification of Ata tephra, one of the wide-spread marker tephra which indicates the Last Interglacial culmination period in Japan by Sasaki et. al(2002). It was thought that marine terraces of the eastern coast of South Korea had been formed by the steady-state uplifting during the Quaternary glacio-eustatic sea level changes(Choi, 1997). The uprift rate of 10cm/1,000years had been proposed in the eastern coast of South Korea based on the former shoreline altitude(18m) of the above Eupcheon 15 terrace. Therefore, it can be estimated that Eupcheon 1 terrace had been formed in the early Pleistocene from the above uprift rate. The OSL dating for the samples of Eupcheon 7, 9, 13, 15 and 16 terraces and identification of marker tephra in the terrace deposits are in progress. It is expected that more elaborate chronology on themarine terraces of the eastern coast of South Korea could be established by these absolute dates and marker-tephra.

• Proceedings of the Korean Association of Geographic Inforamtion Studies Conference
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• 2003.04a
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• pp.261-267
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• 2003

사회의 빠른 변화 속에서 지자체가 처리해야 할 정보의 양과 행정수요는 점점 증가하고 있으며, 의사결정과 기획을 위한 정보망과 정보시스템의 활용 계획을 수립하여야 하는 필요성은 더욱 증대되고 있다. 도시정보체계(UIS)의 구축은 의사결정의 효율적인 도구로 각광받아 대다수 지자체에서 활발히 진행되고 있다. 그러나 지자체 행정업무의 70～80%가 공간정보와 연계되어 있다는 막연한 기대감에서 출발한 현재의 도시정보체계(UIS) 구축사업은 단지공간정보 관리 중심의 시스템 개발에 치우치게 되었으며, 시설물 관리 분야에 대한 사업을 이미 수행한 지자체에서는 향후 어떠한 사업들을 전개해야 할 지에 대한 보다 다양하고 구체적인 비전을 가지지 못하고 있는 것이 우리의 현실이 아닌가라는 우려를 하게 되었다. 따라서 본 연구에서는 도시정보체계(UIS)의 새로운 비전 수립을 위해서는 막연하게 제시되고 있는 공간정보 관련성 분석을 보다 세분화하여 수행할 수 있는 공간정보 관련성 분석 모형을 제시함으로써 지자체 도시정보체계(UIS) 구축사업의 현재를 돌아보고 보다 발전적인 새로운 사업추진의 시각을 고찰해보고자 한다. 본 연구에서는 지자체 업무영역에 대한 보다 세분화된 공간정보의 관련성 분석을 위해 공간정보를 업무관점, 업무-정보산출물 관점, 데이터구축관점, 정보관점, 서비스관점으로 세분화여 하여 접근하였으며, 이를 종합하여 최종적인 공간정보 관련성 분석 모형을 구성하였다. 또한 지속적인 도시정보체계(UIS) 사업의 추진을 위해 시간적 개념의 변화 양상을 제시함으로써 GIS의 발달단계에 따라 어떠한 부분에 비중을 둔 사업의 추진이 이루어져야 하는지에 대해서 제시하고자 하였다. 본 연구를 통해 시설물 관리 중심의 도시기반정보화에 편중된 도시정보체계의 구축사업의 시각이 행정정보화, 생활정보화, 산업정보화 등 다양한 분야와 결합하여 보다 큰 시너지 효과와 사용자 중심의 서비스 개선을 창출할 수 있는 기반을 제공할 것을 기대해 본다.. 이상의 결과를 종합해볼 때, ${\beta}$-glucan은 고용량일 때 직접적으로 또는 $IFN-{\gamma}$ 존재시에는 저용량에서도 복강 큰 포식세로를 활성화시킬 뿐 아니라, 탐식효율도 높임으로써 면역기능을 증진 시키는 것으로 나타났고, 그 효과는 crude ${\beta}$-glucan의 추출조건에 따라 달라지는 것을 알 수 있었다.eveloped. Design concepts and control methods of a new crane will be introduced in this paper.and momentum balance was applied to the fluid field of bundle. while the movement of′ individual material was taken into account. The constitutive model relating the surface force and the deformation of bundle was introduced by considering a representative prodedure that stands for the bundle movement. Then a fundamental equations system could be simplified considering a steady state of the process. On the basis of the simplified model, the simulation was performed and the results could be confirmed by the experiments under various conditions.뢰, 결속 등 다차원의 개념에 대한 심도 깊은 연구와 최근 제기되고 있는 이론의 확대도 필요하다. 마지막으로 신뢰와 결속에 영향을 미치는 요소간의 개념적 분류, 차이의 검증, 영향력 등

• Journal of the Korean Society of Groundwater Environment
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• v.5 no.3
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• pp.155-161
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• 1998

Retardation effect of heavy metals in soils caused by adsorption onto the surfaces of solids particles is well known phenomenon. In this study, we investigated the retardation effect on the mobility of a Zn in a sandy soil by conducting batch and column tests. The column test consisted of monitoring the concentrations of effluent versus time known as a breakthrough curve (BTC). We used NaCl and ZnCl$_2$ solutions with the concentration of 10 g/L as a tracer, and injected them respectively into the inlet boundary of the soil sample as a square pulse type, and monitored the effluent concentrations at the exit boundary under a steady state condition using an EC-meter and ICP-AES. The batch test was conducted based on the standard procedure of equilibrating fine fractions collected from the soil with various initial ZnCl$_2$ concentrations, and analysis of Zn ions in the equilibrated solutions using ICP-AES. The results of column test showed that i) the peak concentration of ZnCl$_2$analyzed by ICP was far less than that of either NaCl or bulk electrical conductivity and ⅱ) travel times of peak concentrations for two tracers were more less identical. The relatively low concentration of Zn can be explained by ion exchange between Zn and other cations, and possible precipitation of Zn in the form of Zn(OH)$_2$due to high pH range (7.0∼7.9) of the effluent. The identical result of travel times of peak concentrations indicates that the retardation effect is not present in the soil. The only way to describe the prominent decrease of Zn ion was to introduce decay or sink coefficient in the CDE model to account for irreversible decrease of Zn ions in the aqueous phase.

• Journal of the Korean GEO-environmental Society
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• v.10 no.7
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• pp.125-133
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• 2009

Wastewater sludge had normally filled up in land before revising the law of waste material management in 2003, which does not permit landfill of organic sludge in Korea. After the law, most sludge has been littered in the ocean up to now. However, due to the London Convention 96 Protocol, littering sludge in the ocean will also be prohibited after 2011. This Protocol makes countries find out new methods to treat wastewater sludge. There is no exception in Korea too. Many researchers have urgently try to find out better ways to treat sludge. One of ways is to make sludge recycle energy and the success of it depends on drying method. Specifically, it really depends how to make sludge dry ecologic friendly and economic efficiently. Therefore, wastewater sludge produced in Youngdong was analyzed to make it energy resources in this study. The sludge was tested to analyze the drying and chemical characteristics of it by irradiating microwave. In the result, it is sure that the sludge has little heavy metals as like as others in country side. High calories, 3370 Kcal, shows that it has good potential to be recycle energy. Moreover, weight deduction of the sludge vs. time shows long S-curve and has same deduction ratio. Specifically, S-curve can be divided by three sections based on the curvature points. There are steady state reduction ratio of weight and approximately 80% of weight duction in the second section. This results can be used to estimate the amount of sludge reduction in the full-scale microwave dryer. Drying capacity of microwave shows approximately 1.0 kg/kw/hr. It makes sure that sludge recycle energy has the potential of economic efficiency too.

• Journal of the Korean Chemical Society
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• v.33 no.4
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• pp.337-342
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• 1989

Gasless combustion is a vigorous exothermic reaction ignited directly in solid mixture, similar to Thermit reaction. The gasless combustion synthesis has the advantages of rapid processing, energy saving, low processing cost, and high purity of products. The Ti$Si_x$(x = 0.6, 0.8, 1.0, 2.0) systems are prepared by the gasless combustion synthesis without external sintering process. The crystallographic structures of $Ti_5Si_3$, $Ti_5Si_4$ are hexagonal and tetragonal system, respectively. Those of TiSi, $TiSi_2$ are orthorhombic systems. The results of X-ray analysis agree with the JCPDS data. The combustion modes of all combustion reactions are steady state combustions, and the propagation velocities of the combustion waves of $Ti_5Si_3$, $Ti_5Si_4$ and TiSi are greater than 0.6 cm/sec and that of $TiSi_2$ is 0.28 cm/sec.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.19 no.9
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• pp.69-76
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• 2018

The present study analyzed the effect of film hole position of 45 degree ribbed cooling channel on film cooling performance of gas turbine blades. We also investigated the influence of the ribs under the fixed blowing ratio. Three-dimensional numerical model was constructed and extensive simulation was conducted using the commercial code (Fluent ver. 17.0) under steady-state condition. Base on the simulation results, We investigated the cooling effectiveness, flow velocity, streamline, and pressure coefficient. Moreover, We analyzed the effect of cooling hole position on ejection of the secondary flow caused by the rib structure. From the results, It was found that internal flow of the cooling channel forms a vortex pair in the counterclockwise from the top side, and clockwise from the bottom side. For the channels with ribs, the vortex flow generated by the ribs caused a higher pressure difference near the hole outlet, resulting in at least 12% higher cooling effectiveness than the channel without ribs. Additionally, when the hole is located on the left side of the ribbed channel (Rib-Left), it can be found that the secondary flow generated by the ribs hits against wall surface near the hole to form a flow in the direction of the hole inclination angle. Therefore, It is considered that the region where the cooling gas discharged to the blade surface stays in the main flow boundary layer is wider than the other cases. In this case, The largest pressure coefficient difference was observed near the outlet of the hole, and as a result, the discharge of the cooling gas was accelerated and the cooling efficiency was slightly increased.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.21 no.9
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• pp.528-535
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• 2020

Recently, the protection coordination method of DC systems has been presented because renewable energy and distributed resources are being installed and operated in distribution systems. On the other hand, it is difficult to detect ground faults because there is no significant difference compared to a steady-state current in ungrounded IT systems, such as DC load networks and urban railways. Therefore, this paper formulates the detection principle of IMD (Insulation Monitoring Device) to use it as a protection coordination device in a DC system. Based on the signal injection method of IMD, which is analyzed by a wavelet transform, this paper presents an algorithm of detecting ground faults in a DC system in a fast and accurate manner. In addition, this paper modeled an IMD and an ungrounded DC system using the PSCAD/EMTDC S/W and performed numerical analysis of a wavelet transform with the Matlab S/W. The simulation results of a ground fault case in an ungrounded DC system showed that the proposed algorithm and modeling are useful and practical tools for detecting a ground fault in a DC system.

• Fire Science and Engineering
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• v.31 no.6
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• pp.8-15
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• 2017

Most fire victims succumb to smoke inhalation, and fire smoke toxicity from interior materials is increasing with increased use of plastics. Large amounts of hazardous effects of smoke are related to deposition of smoke particles in respiratory tracts, and deposition characteristics are influenced by size distribution of particles. Thus, it is essential to know the size distribution of smoke particles from plastics for hazard analysis of fire smoke. In a recent study, it has been shown that size distributions of smoke particles from PP are different from wood in many aspects. In order to know whether other plastics show the same characteristics as PP, size distributions of smoke particles from four plastic materials (LDPE, PA66, PMMA, and PVC) were measured in real time under each fire type with various temperature and oxygen supply. In this study, smoke particles from different plastics were generated uniformly by using steady-state tube furnace method provided in ISO/TS 19700. Their size distributions were measured by using an electrical low pressure impactor (ELPI). Results of measurements showed that size distributions of smoke particles from these four plastic materials were similar to those from PP in many aspects. However, they were distinctively different from those of wood.

• Journal of Korea Water Resources Association
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• v.33 no.3
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• pp.307-314
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• 2000

This study is to investigate the recurrence characteristics of wet and dry years using over 200 year records of annual rainfall depth including Chosun Age in Korea. As well as analyzing the correlation structure of the raw data, recurrence trends of wet and dry year has been investigated based on several truncation levels (mean, $mean{\pm}0.25stdv.,\;mean{\pm}O.5stdv.,\;mean{\pm}O.75stdv.,\;mean{\pm}stdv.$). Also the transition probability among wet, dry and normal years has been derived for the same truncation levels. and finally the average return periods based on the steady-state probabilities were obtained. This analysis has been applied to not only the entire data but also partial data set of before- and after-the long dry period around 1900 in order to compare and detect the possible difference between the Chukwooki (an old raingauge invented in Chosun age) and the modem flip-bucket style. As a result, Similar pattern of dry and wet year recurrence has been found, but the return period of extremely dry years after the dry period shown longer than that before the dry period. Assuming that the dry and wet years can be defined as $mean{\pm}$ standard deviations, respectively, the return period of the wet years is shown to be about 5~6 years and that of the dry years about 6~7 years.