• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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• 2003.09a
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• pp.87-90
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• 2003

This research examines the feasibility of using laboratory-synthesized nano scale zero-valent iron particles to remove arsenic from aqueous phase. Batch experiments were performed to determine arsenic sorption rates as a function of the nano scale zero-valent iron solution concentration. Rapid adsorption of arsenic was achieved with the nano scale zero-valent iron. Typically 1 mg $L^{-1}$ arsenic (III) was adsorbed by 5 g $L^{-1}$ nano scale zero-valent iron below the 0.01 g $L^{-1}$ concentration within 7min. The kinetics of the arsenic sorption followed pseudo-first-order reaction kinetics. Observed reaction rate constants ( $K_{obs}$) varied between 11.4 to 129.0 $h^{-1}$ with respect to different concentrations of nano scale zero-valent iron. A variety of analytical techniques were used to study the reaction products including HGAAS (hydride generator atomic adsorption spectrophotometer), SEM (scanning electron microscopy) and TEM (transmission electron microscopy). Our experimental results suggest novel method for efficient removal of arsenic Iron groundwater.r.

• The Bulletin of The Korean Astronomical Society
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• v.43 no.1
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• pp.70.3-70.3
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• 2018

외계행성 탐색시스템의 망원경-카메라 제어 시스템 및 소프트웨어 구성과 관측 유틸리티에 대해 소개한다. 망원경 제어 소프트웨어는 천문 위치보정, 포인팅, 돔 회전 등을 담당하는 PC-TCS 프로그램, 망원경 적경-적위 축 서보 제어를 담당하는 full-closed loop PID 컨트롤 프로그램, 포커서, 필터박스, 돔 셔터, 주경냉각, 온도 모니터 등의 보조 시스템을 제어하는 AUX controls 프로그램으로 구성된다. 카메라 제어 소프트웨어는 모자이크로 구성된 여러 CCD를 각각 독립적으로 제어하는 IC(Instrument Control) 패키지와 이들을 총괄 제어하는 ICS(IC Science) 패키지로 구성되며 망원경과 카메라 소프트웨어의 인터페이스 역할을 하는 TCS Agent 프로그램이 포함된다. 관측 진행을 돕는 유틸리티로서 관측제어 명령어 입력 및 관측 스크립트 구동 기능을 제공하는 OBS Agent 프로그램과 가이드 CCD를 이용한 시상 모니터링 및 자동초점조정 프로그램을 개발하여 활용하고 있다. 각 소프트웨어는 UDP, TCP/IP, RS-232, Redis server 등 다양한 인터페이스를 통하여 서로 통신하며, CCD 영상 자료 전달을 위해 RAM(Random Access Memory) 디스크와 Network File System(NSF)을 이용하고 있다.

• Ocean and Polar Research
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• v.25 no.spc3
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• pp.399-408
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• 2003

The behavior of Suspended Sediment Concentrations (SSC) around a silt screen in a microtidal coastal area was hydrodynamically measured. The current speed at the mid-layer about 30m downstream of the screen reduces to about half that at the same distance upstream. It was caused by the contraction of the vertical section due to the screen. Even during a relatively weak storm period the SSC increases to that of the value caused by dredging. Section-averaged SSC at the downstream of the screen is higher by about 60% than that at the upstream, suggesting that the silt screen plays an adverse effect rather than a constructive role in the reduction of SSC generated by dredging.

• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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• 2005.04a
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• pp.53-56
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• 2005

A Laboratory study was conducted to evaluate the kinetics of oxidation of trichloroethylene (TCE) in groundwater by potassium permanganate $(KMnO_4)$, Consumption of permanganate by TCE and aquifer materials was also evaluated to obtain an appropriate injection rate of $KMnO_4$. TCE degradation by $KMnO_4$ in the absence of aquifer material showed effective with pseudo-first order rate constant, $k_{obs}=1.8110^{-3}\;s^{-1}\;at\;KMnO_4=500mg/L$. TCE oxidation by $KMnO_4$ was found to be second order reaction and the rate constant, $k=0.65{\pm}0.08\;M^{-1}s^{-1}$, was independent of pH changes. $KMnO_4$ consumption rate by groundwater sampled from field site was not significant, indicating that groundwater containing negligible amount of dissolved organic matter does not have any influence on the $KMnO_4$ degradation. Meanwhile, aquifer materials from field site were actively reacted with permanganate, resulting in the significant consumption of $KMnO_4$. It might be attributed to the existence of metal oxides in aquifer materials, Based on the rate constants obtained from this study, appropriate injection rate of permanganate and TCE removal rate in groundwater could be estimated.

• 한국지구물리탐사학회:학술대회논문집
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• 2008.10a
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• pp.73-78
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• 2008

We introduce OBS and sonobuoy systems which are the typical wide-angle reflection/refraction seismic recorders made by KORDI for the investigation of crustal structure and the sediment/basement structure in the coastal area. These recording devices are examined for their usage through the test survey. The normal operation of these devices were proved and good recordings were obatined. The head waves are recognized in the sonobuoy records, which shows the possibility of velocity structure survey by the refraction and/or tomography method.

• Bulletin of the Korean Chemical Society
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• v.29 no.4
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• pp.785-789
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• 2008

The present study is the first report of utilizing $TiO_2$ photocatalyst to analytically calibrate the hydroperoxyl radical ($HO_2\;^{\cdot}$). An in-situ calibration method of $HO_2\;^{\cdot}$ is proposed for air monitoring by using an 2-methyl-6-(pmethoxyphenyl)- 3,7-dihydroimidazo-[1,2-a]pyrazin-3-one (MCLA)-chemiluminescence (CL) technique. In this method, $HO_2\;^{\cdot}$($pK_a$ = 4.80) is produced by the ultraviolet (UV) photolysis of immobilized $TiO_2$ using a constant flow rate of air equilibrated water, in which $HO_2\;^{\cdot}$ is controlled by using various lengths of knotted tubing reactor (KTR). The principle of the proposed calibration is based on the experimentally determined halflife ($t_{1/2}$) of $HO_2\;^{\cdot}$ and its empirically observed pH-dependent rate constant, $k_{obs}$, at a given pH. The concentration of $HO_2\;^{\cdot}$/$O_2\;^{\cdot}$− is increased as pH increases. This pH dependence is due to the different disproportionative reactivities between $HO_2\;^{\cdot}$/$O_2\;^{\cdot}$− and $HO_2\;^{\cdot}$/$O_2\;^{\cdot}$−. Experimental results indicate the practical feasibility of the approach, producing very promising method.

• Journal of the Korean Chemical Society
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• v.30 no.6
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• pp.532-537
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• 1986

The kinetics of the reaction of $[Mo_2O_4(H_2O)_6]^{2+}$ with $VO_2^+$ have been studied at $25^{\circ}C$ by spectrophotometric method. Stoichiometry of the oxidation of$ [Mo_2O_4(H_2O)_6]^{2+}$ is followed as $Mo_2^V + 2V^V {\rightleftharpoons} 2Mo^{VI} + 2V^{IV}$. Observed rate constants are dependent on $ [H^+]\;and\;[VO_2^+]$. Mechanism for the redox of $[Mo_2O_4(H_2O)_6]^{2+}\;and\;VO_2^+$ is proposed and discussed.

• Journal of The Korean Astronomical Society
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• v.39 no.1
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• pp.25-30
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• 2006

We completed four color light curves of the near-contact binary CN And during three nights from September to December 2004 using the 61-cm reflector and BV RI filters at Sobaeksan Observatory. We determined four new times of minimum light (two timings for primary eclipse, two for secondary). Newly obtained BV RI light curves and the radial velocity curves from Rucinski et a1. (2000) were simultaneously analyzed to derive the system parameters of CN And. We used the semi-detached mode 4 of the 2003-version of the Wilson-Devinney binary model, and interpreted the asymmetry of the light curve by introducing two spots; a cool spot on the primary component and a hot spot on the secondary component. New photometric parameters are not much different from those of Cicek et a1. (2005), and it is considered that the system is in the era of broken contact. From the orbital period study with all available timings including our data, we found a continous period decrease with a rate of $P_{obs}=--1.82{\times}10^{-7}\;d\;yr^{-1}$ that can be explained with two possible mechanisms. We think the most likely cause of the period decrease is a thermal mass transfer from the primary to the secondary component, rather than angular momentum loss due to a magnetic stellar wind.

• The Bulletin of The Korean Astronomical Society
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• v.36 no.1
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• pp.87.1-87.1
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• 2011

We analyze the I-GALFA HI 21-cm line survey data in order to study the characteristics of interstellar turbulence in the neutral hydrogen medium in the Galaxy. We select several regions of 4.3 deg x 4.3 deg area near or far from the galactic plane both in the inner and outer Galaxy, transform the power of those regions into Fourier planes and derive one- and two-dimensional power spectra of HI emission. Our Fourier-analysis shows that the iso-power contours generally elongate along the latitude direction more in the outermost spiral arm, which indicates that the HI structure is "filamentary" and mainly aligned along the longitude. At high latitudes or in the interarm region, on the other hand, the iso-power contours are close to circles implying that the HI structures are randomly distributed or "clumpy". In the inner Galaxy, we derive two-dimensional spectra both far from and near the arm and explore the nature of the turbulence.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.22 no.8
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• pp.1652-1658
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• 1997

We analyze the short-term fading characteristics of received signal in urban microcellular environment. In order to analyze the fading signal, we obtain the fading distributions by distance, the received power pattern by arrival angle and the spatial correlation coefficients of fading signal by spacing distance between two antennas. In addition, we compare the distributions of simulated fading signal with the Rician parameter K in various conditions. As the results, it can be seen that the occuring period of deep fade and fade range in microcell are different as the distance between two antennas;besides, the period of fade and fade range in OBS region occur shortly and deeply as compared with those in LOS region. The data used in analysis are obtained by the simulation program using ray tracing technique.