• Journal of Photoscience
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• v.9 no.2
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• pp.308-310
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• 2002

Bacteriorhodopsin (bR) and halorhodopsin (hR), which exist in the membrane of Halobacterium salinarum, are light-driven ion pumps. In spite of high similarity of primary and tertiary structures between bR and hR, these membrane proteins transport different ions, proton and chloride, in the opposite direction. From alignment of the amino acid sequences, Thr-89 of bR is homologous to Ser-l15 of hR from Halobacterium salinarum (shR). X-ray structure of shR has revealed that OH group of this residue directly interacts with CI$\^$-/ Thus, Ser-lI5 of shR is expected to play an important role in CI$\^$-/ binding and transport. In this study, we expressed wild type hR from Natronobacterium pharaonis (PhR) and Sl30A, which corresponds to Ser-l15 of shR, in E. coli in order to clarify binding affinity of chloride ion and photocycle reactions. From the titration with CI$\^$-/, affinity of Sl30A became quite lower than that of WT (WT 6 mM, Sl30A 89 mM). Furthermore, from the flash photolysis with pulse laser of λ$\_$max/ at 532 nm, the reaction rate of SI30A from 0 intermediate to hR ground state was found to become apparently slower than that of WT. The singular value decomposition (SVD) and global fitting analyses of the photocycles were performed to identify all photointermediates and determine the reaction rates.

• Tuberculosis and Respiratory Diseases
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• v.39 no.2
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• pp.176-179
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• 1992

Bronchial webs are rare lesions which often go unrecognized. A 36-year-old female was admitted to our hospital for recurrent cough and dyspnea. A diagnosis of bronchial asthma was made and she was treated with conventional therapy. She did not respond to drug therapy. On the physical examination, there was localized wheezing on the left lung field. By the bronchogram, we found a membrane-like structure in the left main bronchus. A bronchoplasty was performed and now the patient leads her normal life without any medications for asthma.

• BMB Reports
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• v.34 no.4
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• pp.371-378
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• 2001

The Glycoprotein D (gD) gene of the HSV-1 strain F was cloned, sequenced, recombinated into the HcNPV (Hyphantria cunea nuclear polyhedrosis virus) expression vector and expressed in insect cells. The gD gene was located in the 6.43 kb BamHI fragment of the strainF. The open reading frame (ORF) of the gD gene was 1,185 by and codes 394 amino acid residues. Recombinant baculoviruses, GD-HcNPVs, expressing the gD protein were constructed. Spodoptera frugiperda cells, infected with the recombinant virus, synthesized a matured gX-gD fusion protein with an approximate molecular weight of 54 kDa and secreted the gD proteins into the culture media by an immunoprecipitation assay The fusion gD protein was localized on the membrane of the insect cells, seen by using an immunofluorescence assay The deduced amino acid sequence presents additional characteristics compatible with the structure of a viral glycoprotein: signal peptide, putative glycosylation sites and a long C-terminal transmembrane sequence. These results indicate the utility of the HcNPV-insect cell system for producing and characterizing eukaryotic proteins.

• Proceedings of the Korean Vacuum Society Conference
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• 2012.02a
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• pp.542-543
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• 2012

Coherent diffraction imaging (CDI) method using hard x-ray at 5.46 keV was applied to study assembly of Ni and Ni oxide nano structures formed on a Si3N4 membrane. Density distribution of Ni nano-particles was obtained quantitatively with about 15 nm lateral resolution by reconstructing images from the speckle diffraction pattern. In addition, reconstructed images of nickel oxide particles indicated that Ni atoms diffuse out during the oxidation process leaving pores inside the nickel oxide crust. Furthermore, we recognize that really weak phase object, less than 5 nm thickness of Ni residues, can be reconstructed due to the reference particles. We achieved quantitative information of nanometer sized materials and demonstrate the effect of reference particles by using hard x-ray coherent diffractive imaging method.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.4 no.3
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• pp.705-711
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• 2000

A thin film oxide semiconductor micro gas sensor array which shows only 60 mW of power consumption at an operating temperature of $300^{\circ}C$ has been fabricated using microfabrication and micromachining techniques. Excellent thermal insulation of the membrane is achieved by the use of a double-layer structure of $0.1\mum\; thick\; Si_3N_4 \;and\; 1 \mum$ thick phosphosilicate glass (PSG) prepared by low-pressure chemical-vapor deposition (LPCVD) and atmospheric-pressure chemical-vapor deposition (APCVD), respectively. The sensor array consists of such thin film oxide semiconductor sensing materials as 1 wt.% Pd-doped $SnO_2,\; 6 wt.% A1_2O_3-doped\; ZnO,\; WO_3$/ and ZnO. Baseline resistances of the four sensing materials were found to be stable after the aging for three days at $300^{\circ}C$. The thin film oxide semiconductor micro gas sensor array exhibited resistance changes usable for subsequent data processing upon exposure to various gases and the sensitivity strongly depended on the sensing layer materials.

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2017.05a
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• pp.106-106
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• 2017

가스센서는 사내 및 산업 환경에서의 유독성 또는 폭발성 가스 검출, 환경 모니터링, 질병 진단 등 매우 다양한 응용분야에서 큰 관심을 가지고 있다. 반도체 금속산화물(SMOs) 기반의 센서 분야에서는 이들의 감도 및 선택성을 향상시키기 위해 많은 노력을 기울이고 있다. 이는 센서의 선택성을 부여하게 되면 다양한 가스들이 존재하는 환경에서도 검출자가 원하는 가스만의 응답을 얻을 수 있기 때문이다. 본 연구에서는 MOF(Metal-Organic Framwork) 기반 멤브레인으로 ZIF-8(Zeolitic Imidazolate Frameworks 구조들 중 하나) 멤브레인 쉘 층을 이용하여 ZnO 나노선에 형성하였다. ZnO 나노선은 VLS공정 (Vapor-Liquid-Solid)을 이용하여 패턴된 전극을 갖는 $SiO_2$-grown Si 웨이퍼 상에 성장되었고, 성장된 ZnO 나노선은 2-methyl imidazole과 methanol이 포함된 고용체에 넣고 폐쇄된 압력용기 속에서 가열시켜 얻게 된다. 이렇게 얻어진 ZIF-8@ZnO 나노선의 ZIF-8 멤브레인은 분자 체 구조(molecular sieving structure)를 갖게 되며, 이들의 pore 크기는 약 $3.4{\AA}$을 갖는다. 따라서 이보다 더 큰 동적 직경을(kinetic diameter) 갖는 가스 종은 이 멤브레인을 통과할 수 없음을 나타내므로 제작된 시편은 $H_2$(kinetic diameter : $2.89{\AA}$), $C_7H_8$(kinetic diameter : $5.92{\AA}$), 그리고 $C_6H_6$(kinetic diameter : $5.27{\AA}$) 가스들을 각각 사용함으로써 ZIF-8@ZnO 나노선의 센서 특성을 조사했으며, 보다 정확한 비교를 위해 순수한 ZnO 나노선 역시 동일한 조건에서 측정되었다. 결과를 통해, 수소 가스를 제외한 다른 가스들에 대해서는 반응을 하지 않고, 오직 수소 가스에 대해서만 반응을 나타냈으며, 순수 ZnO 나노선의 수소 감응도보다 낮은 감응도를 나타내었다. 이는 멤브레인 쉘 층을 형성함으로써 ZnO 나노선의 표면적이 감소해 가스 분자와의 접촉점을 감소시키기 때문이라고 판단된다. 이와 같은 MOF 멤브레인의 캡슐화 전략은 가스센서뿐 아니라 바이오 센서 및 광촉매 등과 같은 이온 선택성을 필요로 하는 다양한 응용분야에 적용될 수 있을 것으로 기대된다.

• Korean Journal of Materials Research
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• v.8 no.2
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• pp.147-153
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• 1998

Tungsten nitride is very attractive as absorber for X-ray lithographic mask and as a diffusion barrier for interconnecting metallization in Si VLSI technology. Microstructure of tungsten nitride films prepared by RF magnetron sputtering has been investigated as a function of deposition parameter. The crystal structure of sputtered films on silicon nitride membrane depends strongly on the NJAr gas flow ratio(0~18%1, gas pressure(l0~43mTorr). RF power (60~150W), target-substrate distance(4~8cm). Tungsten nitride films deposited at the $N_2/Ar$ gas flow ratio(- 10%). gas pressure(~10mmTorr), RF power(~150W) and target-substrate distance(6cm) are amorphous, but at other conditions are almost rough -surfaced polycrystalline. Amorphous films are very smooth($3.1\AA$ rms) and expected to be excellent absorber for X-ray mask.

• Clean Technology
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• v.24 no.3
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• pp.239-248
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• 2018

In this study, pervaporation experiments of water, ethanol and IPA (Isopropyl alcohol) single components and water/ethanol, water/IPA mixtures were carried out using zeolite 4A membranes developed by Fine Tech Co. Ltd. Those membranes were fabricated by hydrothermal synthesis (growth in hydrothermal condition) after uniformly dispersing the zeolite seeds on the tubular alumina supports. They have a pore size of about $4{\AA}$ by ion exchange of $Na^+$ to the LTA structure with Si/Al ratio of 1.0, and shows strong hydrophilic property. Physical characteristics of prepared membranes were evaluated by using SEM (surface morphology), porosimetry (macro- or meso- pore analysis), BET (micropore analysis), and load tester (compressive strength). Pervaporation experiments with various temperature and concentration conditions confirmed that the zeolite 4A membrane can selectively separate water from ethanol and IPA. Water/ethanol separation factor was over 3,000 and water/IPA separation factor was over 1,500 (50 : 50 wt%, initial feed concentration). Pervaporation behaviors of single components and binary mixtures were predicted using ACM (activity coefficient model), GMS (generalized Maxwell Stefan) model and DGM (Dusty Gas Model). The adsorption and diffusion coefficients of the zeolite top layer were obtained by parameter estimation using GA (Genetic Algorithm, stochastic optimization method). All the calculations were carried out using MATLAB 2018a version.

• Journal of Korean Tunnelling and Underground Space Association
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• v.19 no.2
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• pp.161-177
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• 2017

This paper presents the design considerations and field applications on inflatable structure system to protect rapidly flooding damages in large section tunnel. This inflatable structure system is very valuably used to protect passively and rapidly the possibilities of tunnel damages by flooding threats and unusual leakage to be occurred during and after underground infrastructure. In particular, this system should be necessary in subsea tunnel. The predominant factors in the design of inflatable structure system are the leakage and friction characteristics between the inflater and tunnel liner. The analytical and experimental studies are performed to develop the design considerations and to examine the design parameters of the inflatable structure system. The analytical solutions are developed using membrane theory to suggest the design considerations. The relative friction tests of several fabric materials are also carried out to determine the friction characteristics according to the different friction conditions between inflater and tunnel surface. The test results show that the friction coefficients in wet surface condition are about 20% lower than the values in dry surface condition. In addition, virtual design of tunnel protection system for two virtual subsea tunnel sites which is under reviewing in Korea, is carried out based on this research. It is expected that the results of this research will be very useful to understand the inflater structure design and development the technology of tunnel protection structures in the future.

• Journal of Environmental Science International
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• v.23 no.5
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• pp.943-962
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• 2014

Industrial gas drying, dilute gas mixtures purification, air fractionation, hydrogen production from steam reformers and petroleum refinery off-gases, etc are conducted by using adsorptive separation technology. The pressure swing adsorption (PSA) has certain advantages over the other methods, such as absorption and membrane, that are a low energy requirement and cost-effectiveness. A key component of PSA systems is adsorbents that should be highly selective to a gas being separated from its mixture streams and have isotherms suitable for the operation principle. The six standard types of isotherms have been examined in this review, and among them the best behavior in the adsorption of $CO_2$ as a function of pressure was proposed in aspects of maximizing a working capacity upon excursion between adsorption and desorption cycles. Zeolites and molecular sieves are historically typical adsorbents for such PSA applications in gas and related industries, and their physicochemical features, e.g., framework, channel structure, pore size, Si-to-Al ratio (SAR), and specific surface area, are strongly associated with the extent of $CO_2$ adsorption at given conditions and those points have been extensively described with literature data. A great body of data of $CO_2$ adsorption on the nanoporous zeolitic materials have been collected according to pressure ranges adsorbed, and these isotherms have been discussed to get an insight into a better $CO_2$ adsorbent for PSA processes.