• Archives of Pharmacal Research
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• v.29 no.11
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• pp.1061-1065
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• 2006

A new chiral derivatization agent with sugar moiety, 2,3,4,6-tetra-O-acetyl-${\beta}$-D-galactopyranosyl isothiocyanate (GATC) was synthesized. Several ${\beta}-blockers$ were investigated for the possible separation of the enantiomers by reversed-phase HPLC after derivatization with this new chiral derivatization agent (GATC). GATC was reacted readily with ${\beta}-blockers$ at room temperature and the reaction mixture could directly be injected into the HPLC system. The corresponding diastereomers were well resolved on an ODS column with acetonitrile-ammonium acetate buffer as a mobile phase and monitored at UV 254 nm. The optimization of the derivatization procedure (concentration of GATC, reaction temperature and time) and HPLC conditions (pH and ionic strength of mobile phase) were investigated and compared with GITC.

• Proceedings of the Korean Fiber Society Conference
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• 1990.06b
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• pp.67-67
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• 1990

Three non-ionic and two anioinic spin probes, differing in size and substituent, were synthesized. Their mobility in dried nylon 6 film was investicated by the spin probe technique using electron spin resonance spectrometer. When the size of a spin probe was large and the interaction between the probe molecules and polymer chains existed, the mobility of spin probes decreased. From Arrhenius plots of rotational correlation time, one discontinuity point ($T_d$) was determined. The activation energies for rotation below and above $T_d$ were discussed in terms of the mode of probe rotation. Three spin probes could be viewed as azo dyes having a built-in nitroxide radical. Photolysis of them in dimethylformamide and in nylon 6 film was performed by exposure to 254 nm UV light in the presence of air. It was found that dyes having a built-in nitroxide radical showed better photostability than dyes derived from ${\bata}-naphthol$..

• Electrical & Electronic Materials
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• v.9 no.1
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• pp.59-66
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• 1996

Polyimides containing cyclobutane ring in main chain is known to be thermally stable and able to be developed in organic solvents after photolysis with 254 nm UV light. This type of polyimides can be used as promising positive photoresist in VLSI fabrication process. In the current VLSI process, photoresist films are formed by spin coating. The film thickness is more than several hundred nano meters. It seems that there is room for improvement of film coating process by introducing Langmuir Blodgett technique. Thereby ultra thin film photoresist can be formed, and higher density of integration in VLSI be achieved. In the present work, depositing procedure of LB films of this polyimide was investigated. LB film thickness was measured by ellipsometry to evaluate deposited film status. Chemical imidization procedure was studied to avoid several problems in thermal imidization. The pattern of submicron dimension has successfully formed on LB film of 8nm thick, which found showing good contrast.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2000.11a
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• pp.157-161
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• 2000

Blue phosphor of Ba-Mg-Al-O:Eu$^{2+}$ phase was fabricated by conventional firing techniques under reducing atmosphere and its photoluminescence properties are studied with varying Eu concentration and phost-annealing temperature under air atmosphere. This phosphors were well crystallized with particle size in the range of 3~5um and emitted a blue light at a dominent wavelength 450nm for 254nm UV irradiation. The concentration quenching wit Eu$^{2+}$ was that with increasing Eu concentration the energy transfer between the activator ions steadily improves, so that the excitation energy is transported over larger distances through the lattice before luminescence can occur. Thermal quenching also occurred in this phosphor means that in a host lattice with the $\beta$-alumina structure the bond of an Eu$^{2+}$ ion with the nearest-neighbour oxygen ion is much stronger than in a lattice with the magnetoplumbite structure.cture.

• Journal of Pharmaceutical Investigation
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• v.13 no.2
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• pp.59-65
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• 1983

A convenient high performance liquid chromatographic method for the quantitative determination and content uniformity of prednisolone in tablets is described. The prednisolone was chromatographed using a ${\mu}-Bondapak\;C_{18}$ column and the eluent 70% MeOH at a flow rate 1. 0ml/min. Diethylstilbestrol was used as an internal standard. The UV detector response at 254nm was linear over a range of $10{\sim}60{\mu}g/ml$ under conditions of the analysis. Reproducibility studies gave relative standard deviations of $0.3{\sim}0.5%$.

• Korean Journal of Pharmacognosy
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• v.42 no.3
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• pp.233-239
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• 2011

A reversed phase HPLC method was established for quantitative determination of lignans including schizandrin (1), gomisin A (2), deoxyschizandrin (3), gomisin N (4), and wuweizisu C (5) from Schizandra chinensis using a binary gradient of acetonitrile and water as a mobile phase with UV detection at 254nm. In result, contents of schizandrin (1), gomisin A (2), deoxyschizandrin (3), gomisin N (4), and wuweizisu C (5) in Schizandra chinensis from Moonkyung were 8.41${\pm}$0.30, 3.01${\pm}$0.13, 1.06${\pm}$0.05, 7.69${\pm}$0.30, and 1.68${\pm}$0.06 mg/g, respectively.

• Journal of Korean Society of Water and Wastewater
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• v.11 no.4
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• pp.118-125
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• 1997

Conventional sedimentation method has some limitations for turbidity removal in water treatment because drinking water sources are getting polluted. Removal rates of turbidity using DAF and sedimentation process were compared for various water conditions to know whether DAF is effective to improve sedimentation process. Water samples were clay(gravity 2.65) water 100mg/l, H raw water, mixed water of H raw water and clay 100mg/l, and mixed water of HA(Humic Acid) 5mg/l and clay 100mg/l. Other parameters were temperature, coagulants(Alum, $FeCl_3$), and treatment time. Water temperature greatly affected in removal rates of turbidity for sedimentation and DAF. Generally DAF was more effective in removal rates of turbidity than sedimentation at the same experimental condition. Removal rates of $UV_{254}$ were high to over 90%, and independent of temperature and coagulant.

• Journal of Korean Society of Water and Wastewater
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• v.10 no.2
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• pp.80-87
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• 1996

Treatment efficiencies of water quality parameters such as $KMnO_4$ Demand, $UV_{254}$, Turbidity, and LAS(Linear Alkyl Sulfonate) were compared between DAF(Dissolved Air Flotation) and CGS(Conventional Gravitational Sedimentation). The experimental results showed that DAF is much more efficient in treatment of water quality parameters than CGS. The optimum pH was about 7, and optimum alum($Al_2(SO_4)_3$) dose was about 30 ppm for DAF treatment. Economic aspects were also analyzed for bath systems. Even though production cost per ton of drinking water is slightly higher in DAF than in CGS, it turned out that construction cost and land value of CGS far surpass the production cost. DAF system is superior in removal efficiency of impurities and in production cost as a whole to CGS system.

• Korean Membrane Journal
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• v.11 no.1
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• pp.21-28
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• 2009

We investigated the effect of organic materials on membrane fouling in advanced drinking water treatment by a hybrid module packed with granular activated carbon (GAC) outside multi-channel ceramic microfiltration membrane. Synthetic water was prepared with humic acid and kaolin to simulate natural water resouces consisting of natural organic matter and inorganic particles. Kaolin concentration was fixed at 30 mg/L and humic acid was changed as 2~10 mg/L to inspect the effect of organic matters. Periodic back-flushing using permeate water was performed for 10 sec per filtration of 10 min. As a result, both resistance of membrane fouling (Rf) and permeate flux (J) were influenced highly by concentration of humic acid. It proved that NOM like humic acid could be an important factor on membrane fouling in drinking water treatment. Turbidity and UV254 absorbance were removed up to above 97.4% and 59.2% respectively.

• Proceedings of the Korean Vacuum Society Conference
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• 2010.02a
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• pp.65-65
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• 2010

pn 접합 소자는 반도체 소자의 매우 중요한 기본 구조이다. 최근 들어 나노선과 반도체 기판으로 구성된 pn 접합소자에 대한 연구가 활발히 진행되고 있으나, 나노선을 이용한 대부분의 접합소자는 나노선을 분산하여 소자를 제작하기 때문에 어레이 구조의 소자를 만들기에는 어려움이 있다. 본 연구에서는 성장된 나노선을 슬라이딩 전이하는 방법으로 정렬된 n-$SnO_2$ 나노선과 도핑이 된 p-Si 기판으로 이루어진 pn 접합 소자 어레이 구조를 제작하였다. 제작된 소자의 전류-전압 측정을 통해 정류 (rectification) 작용을 확인하였고 rectification ratio은 수천~수만으로 측정되었다. 소자에 UV (254nm) 빛을 조사하여 광전류의 증가를 확인할 수 있었다. 또한 소자에 15V이상의 전압을 걸어주면 접합 부분에서 EL(electroluminescence) 효과인 발광을 확인 할 수 있었다. 이처럼 나노선과 기판으로 구성된 pn 접합 소자는 다이오드, 태양전지 뿐 아니라 레이저와 LED등으로도 응용될 것으로 예상된다.