• Analytical Science and Technology
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• v.29 no.5
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• pp.219-224
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• 2016

불산 중 극미량 음이온의 고상추출과 이온크로마토그래프를 이용한 고감도 분석법이 개발되었다. 불산 중 불소이온이 고상에 의해 제거하였고 이어서 음이온 (F⁻, CH₃COO⁻, Cl⁻, Br⁻, NO₃⁻, PO₄³⁻, SO₄²⁻)들이 이온크로마토그래프를 이용하여 연속적으로 분리하였다. 고상 추출법에 영향을 주는 각 인자들 (흡착제의 선택, 시료의 부피 및 pH, 용출 용액과 용출용액의 부피)을 결정하였으며 그 결과 흡착제로서 Oasis WAX 컬럼이 가장 우수하였고 1.0 mL의 시료부피, 용출용액으로 50 mM 초산암모늄염 5 mL가 분리능에서 가장 우수하였다. 개발한 방법에 의한 음이온 (Cl⁻, Br⁻, NO₃⁻, PO₄³⁻, SO₄²⁻)들의 방법검출한계는 25 % 불산용액 (w/w) 중에 0.04~0.30 µg/L의 범위를 보였고 정밀도는 20.0와 40.0 µg/L의 농도에서 5 % 이내를 보였다. 한 제조회사에 의한 25 % 불산 중 음이온의 4.2에서 47.5 µg/L의 범위로 모두 검출되었다. 이 방법은 시험절차가 간단하고, 재현성 및 감도가 좋아서 반도체회사에서 불산 중 음이온 불순물을 정도 관리하는데 매우 유용한 방법이 될 것으로 판단된다.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2010.06a
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• pp.164-164
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• 2010

점광원 가정법은 광학계의 초점거리를 LED die 표면의 중심점으로 설정하고 LED 패키지의 발산형태는 이상적인 점광원으로 가정하여 설계하는 방법이며, 가초점 설계법은 focal smear라고 불리우는 초점영역의 가초점을 기준점으로 잡아 설계를 시행하는 방법이다. 실제 LED에서 빛이 발산하는 부분은 점광원이 아닌 부피를 가지고 있는 형태이기 때문에 점이외의 면에서 발생하는 오차와 가초점 영역 설정을 통한 설계는 결과에 오차를 발생시키게 된다. 따라서 구조 분석 실험 장비를 이용한 LED내부 구조를 분석한 후 이를 시뮬레이션 설계에 적용한 결과 기존 설계법에 비해 약 5%의 오차범위를 줄일 수 있었다.

• Journal of the Korean Ceramic Society
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• v.25 no.3
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• pp.217-224
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• 1988

Pore structures of Alkoxide-derived aluminas are investigated by BET Nitrogen Sorption method. Aluminas are derived from hydrolysis of aluminum isopropoxide at 3$^{\circ}$and 8$0^{\circ}C$ with stoichiometric quantities of water in use. The resulting hydrolysates are then subjected to thermal treatment for a fixed period of time from 200$^{\circ}$to 50$0^{\circ}C$ in gradual fashions. The hydrolysates obtained at 3$^{\circ}C$ increase their pore volumes with increasing heat treatment, exhibiting their pore-size distributio as twinpeaked. In contrast, the reverse is true to the hydrolysates obtained at 8$0^{\circ}C$, showing their pore size distribution as single-peaked. This suggests that the pore shapes of the former shall be slit-shaped, whilst whose as the latter shall be of a ink-bottle shape. All the evidence indicates that the hydrolytic temperatures play an important role not only in determining the pore shapes of the alumina samples, but in controlling the liberation of structural water in the alumina layers. It is also, surmized that the subsequent heat treatment may at best affect the mode of pore size distribution for the resulting alumina product(s).

• Journal of the Computational Structural Engineering Institute of Korea
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• v.24 no.2
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• pp.223-233
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• 2011

A design optimization problem was formulated to minimize the volume of an RC building structure while satisfying design constraints on structural displacements under vertical, wind and seismic loads. We employed metamodel-based design optimization using design of experiments, metamodeling and optimization algorithm to circumvent the difficulty of the automation of structural analysis procedure. Especially, we proposed a design approach of repetitive design optimizations by stages with changing the side constraint values on design variables and limit values on design constraints until a satisfactory design result was obtained. Using the proposed design approach, the volume of the RC building structure has been reduced by 53.3 % compared to the initial one while satisfying all the design constraints. This design result clearly shows the validity of the proposed design approach.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.21 no.1
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• pp.34-40
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• 2011

The bulk density, water absorption and microstructure of the artificial aggregates were controlled as a function of sintering temperature (1100 and $1200^{\circ}C$) and time (10~60 min) in the fabrication process of the artificial aggregates by the direct sintering process using dredged soil, the inorganic wastes. Also, the physical properties of the artificial aggregates fabricated according to the different sintering methods such as the direct sintering method used in this study and the increasing temperature sintering method used in the previous report, were compared and analysed. The bulk density of aggregates sintered at $1200^{\circ}C$ by the direct sintering method showed below 1.0, and the thickness of a shell and the pore size of the black core were increased with sintering temperature. Also, in the same sintering temperature, the area of black core was decreased, the thickness of shell was increased and the water absorption was decreased with sintering time. The black core of artificial aggregates of bulk density below 1.0 had the similar microstructure, regardless of sintering methods. In contrast, the shell of aggregates fabricated by the increasing temperature sintering method showed more dense microstructure than that by direct sintering method, hence the water absorption of aggregate sintered using direct sintering was relatively high. Thus, the direct sintering method is suitable for fabrication of artificial aggregates in ceramic carriers or absorbents applications.

• Proceedings of the Korean Vacuum Society Conference
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• 2012.08a
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• pp.428-428
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• 2012

CIGS 또는 CIS 태양전지는 높은 흡광계수와 조절가능한 밴드갭 특성으로 인해 높은 광전변환효율을 나타내므로 실리콘 태양전지를 대체할 차세대 태양전지로 주목받고 있다. 그러나 태양전지의 저가화를 위해서는 기존의 동시증발법 또는 스퍼터링을 대신할 수 있는 비진공 방식의 박막제조방법이 요구된다. 다양한 비진공 코팅방법 중에서 용액 또는 콜로이드 전구체를 프린팅하는 방법은 batch 조성이 박막의 조성으로 전사되므로, 전착법에 비해 조성 조절이 용이하다는 장점이 있다. 한편, 콜로이드 공정에 속하는 Cu-In 합금 나노 분말법은 셀렌화 또는 황화 과정 중에 부피가 팽창하는 장점을 활용 가능한 반면, 전구체 박막의 충진밀도가 낮을 경우 열처리를 통한 치밀화에 한계가 생길 수 있는 단점이 있다. 본 연구에서는 합성한 Cu-In합금 분말을 이용하여 전구체 박막을 형성한 후 반응기구가 다른 황 및 셀레늄 분위기에서의 열처리를 통해 소결된 박막의 결정상, 미세구조 및 표면 형상의 차이를 비교하였다.

• Journal of the Korean Chemical Society
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• v.52 no.2
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• pp.118-123
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• 2008

The interaction of the antitumour agent, doxorubicin, with adenine is investigated in an aqueous solution at a concentration of 10-3~10-4 with volume ratios of 1:2. A UV-resonance Raman spectroscopy and surface enhanced Raman spectroscopy are used to determine the binding sites of doxorubicin to adenine and the structural variations of doxorubicin-adenine complexes in an aqueous solution. We identified that the possibilities of doxorubicin interacted with the N7 positions of adenine.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.24 no.10
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• pp.1388-1398
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• 2000

A pipe prover is a flowmeter calibrator used in flow measurement field. Gravimetric and volumetric methods were applied to determine the basic volume of the pipe prover. Uncertainty of its basic volume measurement was evaluated in accordance with the procedure recommended by International Organization for Standardization. The combined standard uncertainty of determining the basic volume was estimated from the sensitivity coefficient and the standard uncertainty of independent variables. It was found that the uncertainties of the weighing and volume measurements have dominant influence on that of the basic volume determination. With the quantitative analysis of the sensitivity coefficient, the contribution of the each variable uncertainty to the combined standard uncertainty of the basic volume is shown clearly.

• Korean Journal of Food Science and Technology
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• v.29 no.3
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• pp.492-496
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• 1997

Purple sweet potato pigment extract was concentrated using both membrane separation method and vacuum concentration method. The pigment extract (anthocyanin content 1.6 g/L) was concentrated $({\times}25)$ after 5 hr of continuous operation of a nanofiltration to get anthocyanin content of 10.6 g/L. Total solid content also increased continuously while the flux decreased continuously during the concentration process. Degradation index (DI) changes of concentrated pigment solution were insignificant during the whole concentration process which is indicating that the nanofiltration method does not affect color degradation of anthocyanin pigment. For the comparison test, the same pigment extract was concentrated using a rotary vacuum evaporator at temperatures of 40 and $60^{\circ}C$. At both temperatures, pigment content increased in a similar manner during concentration $({\times}5)$. However, DI value at $60^{\circ}C$ increased while that at $40^{\circ}C$ did not change appreciably. Total color difference value changed only slightly by nanofiltration and $40^{\circ}C$ while changed significantly by $60^{\circ}C$. These indicate that a membrane filtration method is more effective in concentrating purple sweet potato pigment extract than a vacuum concentration method by high temperature.

• Proceedings of the Korean Radioactive Waste Society Conference
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• 2004.06a
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• pp.131-132
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• 2004

원자력연구소에 보관 중인 오염 토양폐기물을 토양 세척법으로 제염하여 비 방사성폐기물화 한다면 그 부피를 10% 이하로 저감시킬 수 있으며 연구소의 고체 방사성폐기물 저장 용량을 크게 늘릴 수 있다. 1988년 발견 당시 오염 토양 폐기물의 주요 방사성 핵종은 Co-60 이었는데 시간경과에 따라 Cs-134, 137 이 주요 방사성 핵종이 되었다. 오염토양 폐기물의 60 % 이상은 방사능 농도가 극히 낮아 물리적으로 입도를 분리하거나 수 세척에 의해 비 방사성폐기물화 할 수 있음을 파악하였다.(중략)