유기산 추출에 의한 철 폐광산 오염토양의 복원

정의덕,강신원,백우현 한국환경과학회 2000 한국환경과학회지 Vol.9 No.1

A study on the remediation of heavily Fe ion contaminated soils from abandoned iron mine was carried out, using ex-situ extraction process. Also, oxalic acid as a complex agent was evaluated as a function of concentration, reaction time and mixing ratio of washing agent in order to evaluate Fe removability of the soil contaminated from the abandoned iron mine. Oxalic acid showed a better extraction performance than 0.1N-HCI, i.e., the concentrations of Fe ion extracted from the abandoned mine for the former at uncontrolled pH and the latter were 1,750 ppm and 1,079 ppm, respectively. The optimum washing condition of oxalic acid was in the ratio of 1:5 and 1:10 between soil and acid solution during 1 hr reaction. The total concentrations of Fe ion by oxalic acid and EDTA at three repeated extraction, were 4,554 ppm and 864 ppm, respectively. The recovery of Fe ions from washing solution was achieved, forming hydroxide precipitation and metal sulfide under excess of calcium hydroxide and sodium sulfide. In addition, the amounted of sodium sulfide and calcium hydroxide for the optimal recovery of Fe were 15g/ℓ and 5g/ℓ from the oxalic acid complexes, respectively.

유기산을 이용한 납 요염토양의 복원에 관한 연구

정의덕,강신원,박덕수,신학기,백우현 한국환경과학회 2000 한국환경과학회지 Vol.9 No.5

A study on the removal of Pb ion from Pb-contaminated soil was carried out, using ex-situ extraction process. Tartaric acid (TA) and iminodiacetic acid sodium salt (IDA) as a washing agent were evaluated as a function of concentration, reaction time, mixing ratio of washing agent and recycling of washing agent. TA showed a better extraction performance than IDA. The optimum washing condition of TA and IDA were in the ratio of 1 : 15 and 1 : 20 between soil and acid solution during 1 hr reaction. The total concentrations of Pb ion by TA and IDA at three repeated extraction, were 368.8 ppm and 267.5 ppm, respectively. The recovery of Pb ion from washing solution was achieved by adding calcium hydroxide and sodium sulfide, form the precipitation of lead hydroxide and lead sulfide, and optimum amounts of sodium sulfide and calcium hydroxide were 7 g/ℓ for the TA washing solution and 4 g/ℓ , 5 g/ℓ for the IDA washing solution, respectively. The efficiency of recycle for TA and IDA washing solution were 78.8%, 95.1% and 89.2%, 96.6%, at third extractions under Na_2S and Ca(OH)_2, respectively.

수돗물과 원적외선 기능수의 수질 특성의 비교

백우현,정의덕,윤천기 한국환경과학회 2000 한국환경과학회지 Vol.9 No.5

The characteristics of Far-infrared rays mineral water(FIR water) have been compared to the tap water by means of relationship between FIR water and Nuclear Magnetic Resonance spectroscopy(NMR), FIR water and thermography, FIR water and velocity of blood, FIR-water and pH, FIR water and dissolved oxygen(DO), FIR water and Oxidation-Reduction Potential(ORP), using the development FIR water purification of grand prix system. From the experimental result are quite satisfactory when compared with the tap water. Also, the FIR water were evaluated to see if those are tasty and healthy using the Hashimoto's Mineral Balance Index. As a result, FIR-water was found as tasty and healthy.

A FLOW AND PRESSURE DISTRIBUTION OF APR+ REACTOR UNDER THE 4-PUMP RUNNING CONDITIONS WITH A BALANCED FLOW RATE

Euh, D.J.,Kim, K.H.,Youn, Y.J.,Bae, J.H.,Chu, I.C.,Kim, J.T.,Kang, H.S.,Choi, H.S.,Lee, S.T.,Kwon, T.S. Korean Nuclear Society 2012 Nuclear Engineering and Technology Vol.44 No.7

In order to quantify the flow distribution characteristics of APR+ reactor, a test was performed on a test facility, ACOP ($\underline{A}$PR+ $\underline{C}$ore Flow & $\underline{P}$ressure Test Facility), having a length scale of 1/5 referring to the prototype plant. The major parameters are core inlet flow and outlet pressure distribution and sectional pressure drops along the major flow path inside reactor vessel. To preserve the flow characteristics of prototype plant, the test facility was designed based on a preservation of major flow path geometry. An Euler number is considered as primary dimensionless parameter, which is conserved with a 1/40.9 of Reynolds number scaling ratio. ACOP simplifies each fuel assembly into a hydraulic simulator having the same axial flow resistance and lateral cross flow characteristics. In order to supply boundary condition to estimate thermal margins of the reactor, the distribution of inlet core flow and core exit pressure were measured in each of 257 fuel assembly simulators. In total, 584 points of static pressure and differential pressures were measured with a limited number of differential pressure transmitters by developing a sequential operation system of valves. In the current study, reactor flow characteristics under the balanced four-cold leg flow conditions at each of the cold legs were quantified, which is a part of the test matrix composing the APR+ flow distribution test program. The final identification of the reactor flow distribution was obtained by ensemble averaging 15 independent test data. The details of the design of the test facility, experiment, and data analysis are included in the current paper.

NOTES ON A QUESTION RAISED BY E. CALABI

Euh, Yunhee,Sekigawa, Kouei Korean Mathematical Society 2016 대한수학회보 Vol.53 No.1

We show that any orthogonal almost complex structure on a warped product Riemannian manifold of an oriented closed surface with nonnegative Gaussian curvature and a round 4-sphere is never integrable. This provides a partial answer to a question raised by E. Calabi.

Effect of rolling on the thermo-physical properties of SiCp/Al composites fabricated by plasma spraying

Euh, Kwangjun,Kang, Suk Bong Elsevier 2005 Materials science & engineering. properties, micro Vol.395 No.1

<P><B>Abstract</B></P><P>Aluminum (Al) matrix composites reinforced by SiC particulates (SiCp/Al) were fabricated by the atmospheric plasma spraying. The composite powder, as a feedstock for plasma spraying, was prepared by ball milling of pure Al powders with 55 vol.% SiC particles. The feedstock was deposited into a freestanding bulk composite sheet on a graphite substrate by atmospheric plasma spraying. As-sprayed composites had a great amount of porosity, which deteriorates the thermo-physical properties, especially the thermal conductivity. In order to reduce the porosity of the plasma-sprayed SiCp/Al composite sheets, rolling processes were carried out at the room and elevated temperature with the thickness reduction of about 20%. The thermal conductivities of the rolled composites were considerably enhanced with the decrease of the porosity in the composites, while the coefficients of thermal expansion (CTEs) of the composites were slightly affected by the rolling process.</P>

Korea's Financial Reform

Euh, Yoon Dae,Amsden, Alice H 고려대학교 경영대학 1990 경영논총 Vol.33 No.1

Because Korea's economy has grown so fast, its financial reforms have been a subject of curiosity in other developing countries. The Korean financial system has changed in the 1980s in conjunction with rapid industrial transformation and external pressures. Yet it would be misleading to characterize such change simply as a move towards freer markets. There has been some liberalization of financial markets in Korea, but the financial system continues to operate within the context of industrial policy. Crisis-avoidance and the objectives of financial reform have largely been achieved by means of creating new institutions or adapting old ones, rather than by relying on the price mechanism. Improved efficiency in the delivery of financial services has not necessarily been dependent on liberalizing interest rates. A knowledge of Korea's financial reforms may help other developing countries establish equivalent, if different, institutions to achieve their own financial goals. Part Ⅰ summarizes the changes that Korea s financial system has undergone in the 1980s. Part Ⅱ examines Koreas financial system within the context of industrial policy. Two episodes are examined : The system of bank credit allocation before the 1980s, and the move towards the development of a stock market and direct finance after 1980. Part Ⅲ penetrates more deeply into the cavernous gulf dividing myth and reality in the Korean model. The issues considered are the degree to which the Korean economy was ailing at the time it launched its reforms ; the issue of how to measure the efficiency of capital markets : the relationship between liberalization and equity ; and the degree to which savings are related to interest rates. Because this essay is concerned principally with financial reform in relation to industrialization rather that macroeconomic management, relatively little is said about the reform of monetary policy. A short section in Part Ⅰ briefly reviews the outstanding developments.

ORTHOGONAL ALMOST COMPLEX STRUCTURES ON THE RIEMANNIAN PRODUCTS OF EVEN-DIMENSIONAL ROUND SPHERES

Euh, Yunhee,Sekigawa, Kouei Korean Mathematical Society 2013 대한수학회지 Vol.50 No.2

We discuss the integrability of orthogonal almost complex structures on Riemannian products of even-dimensional round spheres and give a partial answer to the question raised by E. Calabi concerning the existence of complex structures on a product manifold of a round 2-sphere and of a round 4-sphere.

Characteristic function of Cayley projective plane as a harmonic manifold

EUH, Yunhee,PARK, JeongHyeong,SEKIGAWA, Kouei 'Department of Mathematics, Hokkaido University' 2018 Hokkaido mathematical journal Vol.47 No.1

Simulation and Performance Evaluation of a Parabolic Solar Collector and a Boiler for Brine Reduction

( Euh S. H. ) 강원대학교 농업생명과학연구원(구 농업과학연구소) 2017 강원 농업생명환경연구 Vol.29 No.2

Salt management technique in irrigated agriculture is becoming more important at the San Joaquin Valley of California as well as a number of other areas worldwide. Concentration and evaporation systems using solar energy are being developed in California for salt separation and recovery from drainage water. A model for the parabolic solar collector yielded accurate predictions relative to experimental data for fluid temperature changes and peak fluid temperatures. The peak temperature measured at 72°C was accurate when compared to the calculated results. The evaporation rate of the boiler was 82 kg/h from the model prediction and 76 kg/h from experimental measurements. The predicted efficiencies of the parabolic solar collector and the boiler were approximately 64% during the daytime and 70%, respectively. The cost per kg of dry salts based on net present worth (NPW) for the boiler prototype was $0.90 and $1.34 based on equivalent uniform annual cost (EUAC) with respect to 1 year, respectively, and the costs decreased as the boiler capacity increased.