• Journal of the Korean Vacuum Society
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• v.2 no.2
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• pp.209-219
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• 1993

Evaporated Al/Pd thin films were irradiated with various doses to produce intermetallic compounds. In order to study the first phase formation and phase sequence, RBS and TEM studies have been used. It was found that the initial phase formed by irradiation of $5{\times}10^{15}Ar^+/cm^2$ was $Al_3Pd_2$, while $1.5{\times}10^{16}Ar^+/cm^2$ gave the subsequent phase of AlPd. This phenomenon was analysed using effective heat of formation (${\Delta}$H') model. The experimental results agree with that predicted by effective heat of formation model. This model has been extended to predict the first phase formation and phase sequence by ion beam mixing in metal/Si systems as well as metal-metal systems.

• Journal of the Mineralogical Society of Korea
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• v.31 no.3
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• pp.173-182
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• 2018

The precipitation and phase transformation processes of iron minerals in acid mine drainage have a great influence on the behavior of trace elements in drainage. However, it is not easy to accurately trace these processes in natural environments, and therefore, most studies have carried out in the laboratory to obtain the information on the precipitation and transformation of those minerals. In this study, the precipitation of minerals and the changes of trace elements in drainage water were investigated at different pH values in actual acid mine drainage collected from the Dalsung mine. The amount of some precipitated minerals was not enough for the mineral identification. However, from the minerals identified, amorphous minerals were formed first, and then goethite was precipitated probably from schwertmannite. When the pH of the sample was high (10), amorphous phases of minerals were still observed at even high pH (pH 10). With increasing time, the pH values decreased by precipitation and transformation of minerals. All the elements showed low concentrations at high pH (8, 10), which might be due to the precipitation of minerals at high pH and the effect of surface charge, and the concentrations of elements gradually increased with time. In the case of sulfur, it also increased in water due to the transformation of schwertmannite to goethite.

• Journal of Chest Surgery
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• v.36 no.4
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• pp.289-292
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• 2003

Primary malignant melanoma occurring in the lung is very rare and only few cases have been reported in the literatures. We have experienced one case of primary malignant melanoma of the right middle lobe. The patient was a 65-year-old male who had cough with blood tinged sputum for one month. Chest computed tomography showed about 4.5$\times$3 cm sized mass at the right middle lobe encasing the bronchus. Percutaneous needle biopsy was performed and confirmed to malignant melanoma. Physical examination and additional clinical history showed that the mass had not metastasized to other possible primary sites. The patient underwent thoracotomy with right middle lobe lobectomy. Histologically, the tumor showed sheets of tumor cells that have nuclear atypia and melanin pigment Postoperative course was uneventful and the patient has been followed up for 24 months with no recurrence.

• Applied Chemistry for Engineering
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• v.24 no.5
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• pp.443-455
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• 2013

Electrochemical studies on charge transfer reactions across the interface between two immiscible electrolyte solutions (ITIES) have greatly attracted researcher's attentions due to their wide applicability in research fields such as ion sensing and biosensing, modeling of biomembranes, pharmacokinetics, phase-transfer catalysis, fuel generation and solar energy conversion. In particular, there have been extensive efforts made on developing sensing platforms for ionic species and biomolecules via gelifying one of the liquid phases to improve mechanical stability in addition to creating microscale interfaces to reduce ohmic loss. In this review, we will mainly discuss on the basic principles, applications and future aspects of various sensing platforms utilizing ion transfer reactions across the ITIES. The ITIES is classified into four types : (i) a conventional liquid/liquid interface, (ii) a micropipette supported liquid/liquid interface, (iii) a single microhole or an array of microholes supported liquid/ liquid interface on a thin polymer film, and (iv) a microhole array liquid/liquid interface on a silicon membrane. Research efforts on developing ion selective sensors for water pollutants as well as biomolecule sensors will be highlighted based on the use of direct and assisted ion transfer reactions across these different ITIES configurations.

• Polymer(Korea)
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• v.36 no.6
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• pp.776-788
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• 2012

Octa[8-{4-(4'-cyanophenylazo)phenoxy}]octyl and octa[8-{4-(4'-cyanophenylazo)phenoxycarbonyl}]heptanoated disaccharide derivatives were synthesized by reacting cellobiose, maltose, and lactose with 1-{4-(4'-cyanophenylazo) phenoxy}octylbromide or 1-{4-(4'-cyanophenylazo)phenoxycarbonyl}]heptanoyl chloride, and their thermotropic liquid crystalline and photochemical phase transition behavior were investigated. All the {(cyanophenylazo)phenoxy} octyl disaccharide ethers (CADETs) formed monotropic nematic (N) phases, whereas all the {(cyanophenylazo) phenoxycarbonyl}heptanoated disaccharide esters (CADESs) exhibited enantiotropic N phases. Compared with CADETs, CADESs showed higher isotropic (I)-to-N phase transition temperatures. Photoirradiation of the disaccharide derivatives in a glass cell or in a cell with a rubbed polyimide (PI) alignment layer at a N phase resulted in disappearance of the N phase due to trans-cis photoisomerization of azobenzene, and the initial N phase was recovered when the irradiated sample was kept in the dark because of cis-trans thermal isomerization and reorientation of trans-azobenzenes. The rates of the photochemical N-I and the thermal I-N phase transition of disaccharide derivatives in a cell with a rubbed PI alignment layer were faster than those in a glass cell, and were significantly different from those observed for the monomesogenic compounds containing cyanoazobenzene and the 4-{4'-(cyanophenylazo)phenoxy}octyl glucose and cellulose ethers. The results were discussed in terms of difference in cooperative motion of azobenzene groups due to the flexibility of the main chain, the number of mesogenic units per repeating units, and the distance between the azobenzene groups.

• Journal of the Korean Vacuum Society
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• v.4 no.1
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• pp.51-59
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• 1995

(001)방향 GaAs 기판과 Si/Co 박막의 계면반응 및 상평형에 관한 연구를 300-$700^{\circ}C$ 열처리 구간에서 행하였다. 반응에 의한 상전이 과정은 glancing angle X-ray diffraction(GXRD), Auger electron spectroscopy(AES) 및 cross-sectional transmission electron microscopy(GXRD), Auger electron spectroscopy(AES) 및 corss-sectional transmission electron microscopy(XTEM)을 이용하여 분석하였다. Si/Co/GaAs계의 계면반응에서 Co는 $380^{\circ}C$에서 GaAs 기판 및 Si와 반응하여 Co2GaAs과 Co2Si상을 형성하였다. $420^{\circ}C$에서 열처리 후, Co층은 모두 소모되었으며 단면구조는 Si/CoSi/CoGa(CoAs)/Co2GaAs/GaAs으로 전이되었다. $460^{\circ}C$까지 온도를 올려 계속적인 반응을 일으키면 CoGa와 CoAs이 분해되면서 CoSi가 성장하였고, $600^{\circ}C$에서는 Co2GaAs마저 분해되고 CoSi상이 성장하여 GaAs와 계면을 형성하였다. CoSi와 GaAs사이의 계면은 $700^{\circ}C$의 고온까지 안정하였으며 이러한 계면반응 결과는 계산에 의하여 구한 Si-Co-Ga-As 4원계 상태도로부터 이해될 수 있었다.

• Membrane Journal
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• v.11 no.2
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• pp.89-95
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• 2001

Polysulfone membranes containing an inorganic fluor, cerium activated yttrium silicate (CA Y5), were prepared via the phase inversion technique. The casting solutions with the fluor' were solidified to result in a membrane by using two different nonsolvent coagulants, water and isopropanol. In the process, the fluor worked as a monitioring agent for investigating the characteristics of the phase inversiun process. On the initial contact with water as nonsolvent, the induction of rapid polymer collapse results.in the entrapment of the fluor in the formed membrane structure. Impregnated fluor is dispersed in the polymer structure rather than being enveloped by polymer molecules. In comparison, the fluor is localized in the cell-like structure of membrane, as the cast solution film is cuagulated by immersion into a isopropanol bath.

• Proceedings of the Korean Vacuum Society Conference
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• 1999.07a
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• pp.34-34
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• 1999

토카막(Tokamak)에서는 플라즈마(plasma)로 불순불(impurity)의 유입을 방지하기 위해 고진공을 유지해야 하며 이를 위해 가열탈리(backing), 방전세정(discharge codanning) 등 wall conditioning이 기본적으로 요구된다. KT-1 토카막은 실험실 이전에 따른 해체로 인해 진공용기(vacuum vessel) 가 대기압 하에 수개월 동안 노출되어 있었기 때문에 재조립 후 가열 탈 리가 필수적이나 진공용기의 외부에 saddle loop coil을 비롯해 Rogowski, diamagnetic coil, poloidal field coil 등 많은 magnetic pick up coil 들이 설치되어 있어 열선 등 일반적인 방법으로 가열 탈 리가 어려운 상황이다. 따라서 KT-1 토카막에서는 전자석 코일에 상전원을 부가하였을 때 진공용기에 발생하는 유도가열 (inductive heatin)을 이용해 가열 탈리를 시도하였다. 유도 가열 탈리(inductive backing)는 토로이달 자장 코일(toroidal field coil)과 가열 저장 모일(ohmic heating coil)을 각각 이용하여 코일의 온도가 6$0^{\circ}C$ 이하가 유지되는 코일 전류 범위내에서 수행하였으며 먼저 이 둥 경우에 있어서 진공용기의 온도분포를 비교하엿다. 그리고 가열 탈리 기간 및 그 전, 후의 진공압력과 잔류기체 분압을 측정, 분석하였다. 유도가열에 의한 방법으로 KT-1 토카막에서 얻은 탈리온도는 12$0^{\circ}C$정도로 비교적 낮았으나 탈리 시간을 연장하여 탈리효과를 어느 정도 보상할 수 있으며 일반적인 가열 탈리가 여려운 경우 유도 가열 탈 리가 채택될 수 있는 또 하나의 방법이라 볼 수 있다.

• Membrane Journal
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• v.19 no.2
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• pp.104-112
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• 2009

Ultrafiltration membranes (UF) were manufactured by the conventional phase inversion method using an additives with N-methyl-2-pyrrolidinone as a solvent. Characteristics of performance could be controlled by the preparation conditions and the operating methods. The fouling resistance was observed by the relative ratio of permeate flux $(J_t)$/pure water flux $(J_o)$. Compared with the anion charged membranes and its original polyamide membrane, fouling resistance to the protein was increasing in proportion to the ion exchange capacity. The relative flux for the bovin serum albumin (BSA) solution increased as pH value further away from isoelectric point of BSA. The hydrophilicity of a membrane, the pH condition, and the operating temperature played the important role in the membrane permeations.

• Applied Chemistry for Engineering
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• v.7 no.4
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• pp.726-734
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• 1996

This study was carried oui to find a proper heat storage material and iris container for the thermal energy recovery system of a vehichle. For this purpose, various phenomenon during phase change from solid to liquid and vice versa for three kind material, octahydrate barium hydroxide, naphthalene and acetamide, are experimentally investigated. Also three type material such as pyrex glass, polyethylene and cupper are tested the feasibility as being a container of heat storage material. From this experimental results, $Ba(OH)_2{\cdot}8H_2O$ showed high possibility as good storage media with condition of long life cycle and stable phase change, and cupper was found out as proper container of $Ba(OH)_2{\cdot}8H_2O$.