• 대한화학회지
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• 제26권2호
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• pp.88-94
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• 1982

요소공장의 굴뚝에서 방출되는 가스상 암모니아와 입자상 암모늄을 측정하여 대기중에서 암모니아가 암모늄으로 전환되는 속도를 추정하였다. 암모니아가 암모늄으로 전환되는 것은 대기중에서의 수송시간에 따라 2단계로 나누어진다. 수송 초기 15분동안의 전환속도는 3.2%ㅡmin$^{-1}$이고 그 후는 0.26%min$^{-1}$이었다. 수송 초기단계에서 전환속도가 빠른 것은 굴뚝에서 방출된 유출가스의 온도강하에 의하여 생성된 물방울에 암모니아가 용해하고, 또 이 알칼리성 물방울에서 요소가 분해반응을 일으킴으로써 암모늄의 농도가 급격히 증가하였기 때문인 것으로 추정되었다. 암모니아 가스의 반감기는 수송 초기단계에서 약 16분이고, 그 후는 192분이었다. 측정기간에 있어서 입자상 암모늄염과 대기온도, 상대습도, 이산화황, 질소산화물 및 부유분진 농도와의 사이에는 상관관계가 관찰되지 않았다.

• 해양환경안전학회:학술대회논문집
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• 해양환경안전학회 2005년도 춘계학술발표회
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• pp.161-165
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• 2005

Recently, it is on the increase interest for Al alloy with new material for ship application to substitute for FRP ship. The reason is thatAl alloy ship has beneficial characteristics such as high sea speed, increase of loadage and easy to recycle compared with FRP ship. In this paper, mechanical and electrochemical properties are investigated by slow strain rate test experiment in various applied potential condition. These results will provide as reference data to design ship by deciding optimum protection potential regard to hydrogen embrittlement and stress corrosion cracking. In general, Al and Al alloys are not corroded with forming film which has the corrosion resistance property in neutral solution. However, it was observed that formation and destruction of passive film by $Cl^-$ ion in sea water environment. At comparison of current density after 1200 sec in potentiostatic experiment, the current density in the potential range of -0.68 $\~$-1.5 V is shown low value. The low current density means protection potential range. Elongation in applied potential of 0 V was high. However, the corrosion protection application in this condition is impossible potential because the toughness is low value by decreasing strength by active dissolution reaction at parallel part of specimen. The film composed with $CaCO_3$ and $Mg(OH)_2$ has a corrosion resistance property. However, the uniform electrodeposition coating at below -1.6 V potential is not formed since the time to form the uniform electrodeposition coating is short. Therefore, it is concluded that mechanical property is poor because effect by hydrogen gas generation is larger than that of electrodeposition coating. It is concluded that the optimum protection potential range from comparison of_maxim urn tensile strength, elongation and time to fracture is -1.3$\~$0.7 V (SSCE).

• 한국세라믹학회지
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• 제50권4호
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• pp.301-307
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• 2013

SiC hollow fiber was fabricated by curing, dissolution and sintering of Al-PCS fiber, which was melt spun the polyaluminocarbosilane. Al-PCS fiber was thermally oxidized and dissolved in toluene to remove the unoxidized area, the core of the cured fiber. The wall thickness ($t_{wall}$) of Al-PCS fiber was monotonically increased with an increasing oxidation curing time. The Al-PCS hollow fiber was heat-treated at the temperature between 1200 and $2000^{\circ}C$ to make a SiC hollow fibers having porous structure on the fiber wall. The pore size of the fiber wall was increased with the sintering temperature due to the decomposition of the amorphous $SiC_xO_y$ matrix and the growth of ${\beta}$-SiC in the matrix. At $1400^{\circ}C$, a nano porous wall with a high specific surface area was obtained. However, nano pores grew with the grain growth after the thermal decomposition of the amorphous matrix. This type of SiC hollow fibers are expected to be used as a substrate for a gas separation membrane.

• 자원리싸이클링
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• 제14권6호
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• pp.37-43
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• 2005

페리튬이온전지로부터 회수된 코발트와 리튬 침출액으로부터 화염분부열분해법에 의하여 $LiCoO_{2}$ 나노분말을 제조하였다. 리튬 및 코발트 성분을 함유하는 전극물질은 열처리 및 기계적 처리에 의해 그 농도를 증가 시켰다. 리튬이온전지 양극물질을 질산으로 용해한 다음 침출액중 Li과 Co의 당량비가 1.0 되도록 $LiNO_{3}$로 조절하여 화염분무열분해용 전구체를 제조하었다. 화염분무열분해법에 의해 제조된 $LiCoO_{2}$ 분말의 평균입자크기는 전구체의 몰 농도가 증가하면서 증가되었으며, 화염온도 역시 입자의 크기를 증가시켰다. 변수실험 결과 $11{\~}35nm$ 크기의 결정형 $LiCoO_{2}$ 나노분말을 제조할 수 있었다 또한 나노 $LiCoO_{2}$의 전극재료로서의 가능성을 확인하기 위하여 충방전 특성 평가와 같은 전기화학적 분석을 수행하였다.

• 한국표면공학회지
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• 제50권6호
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• pp.531-535
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• 2017

Enormous amount of waste oyster-shell (OS) has a major disposal problem in coastal regions. OSs have attracted much attention for recycling, because these are mainly composed of calcium carbonate with rare impurities. In this study, we demonstrate the calcareous deposit films on steel plate by using OSs on the basic of cathodic protection technique. The composition of the OSs was analyzed by wavelength dispersive X-ray fluorescence spectrometer. Carbon dioxide gas was pumped into distilled water to make carbonic acid solution for dissolution of OS. The calcareous deposit was characterized by second electron microscope (SEM), energy dispersive X-ray analysis (EDX) and X-ray diffraction. Corrosion rates were estimated by measurements of anodic polarization and immersion test. It is confirmed that calcareous deposits on steel plate are formed under all condition of cathodic protection by using waste OS from the SEM and EDX results. Calcareous deposits on steel by OS provide good corrosion resistance by acting as a barrier to oxygen supply to the steel surface.

• 한국의류학회지
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• 제35권11호
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• pp.1297-1308
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• 2011

This research investigates the application of ZnO (zinc oxide) nanoparticles and $TiO_2$ (titanium dioxide) nanoparticles to polypropylene nonwoven fabrics via an electrospinning technique for the development of textile materials that can decompose harmful gases. To fabricate uniform ZnO nanocomposite fibers, two types of ZnO nanoparticles were applied. Colloidal $TiO_2$ nanoparticles were chosen to fabricate $TiO_2$ nano- composite fibers. ZnO/poly(vinyl alcohol) (PVA) and $TiO_2$/PVA nanocomposite fibers were electrospun under a variety of conditions that include various feed rates, electric voltages, and capillary diameters. The morphology of electrospun nanocomposite fibers was examined with a field-emission scanning electron micro- scope and a transmission electron microscope. Decomposition efficiency of gaseous materials (formaldehyde, ammonia, toluene, benzene, nitrogen dioxide, sulfur dioxide) by nanocomposite fiber webs with 3wt% nano-particles (ZnO or $TiO_2$) and 7$g/m^2$ web area density was assessed. This study shows that ZnO nanoparticles in colloid were more suitable for fabricating nanocomposite fibers in which nanoparticles are evenly dispersed than in powder. A heat treatment was applied to water-soluble PVA nanofiber webs in order to stabilize the electrospun nanocomposite fibrous structure against dissolution in water. ZnO/PVA and $TiO_2$/PVA nanofiber webs exhibited a range of degradation efficiency for different types of gases. For nitrogen dioxide, the degradation efficiency was 92.2% for ZnO nanocomposite fiber web and 87% for $TiO_2$ nanocomposite fiber web after 20 hours of UV light irradiation. The results indicate that ZnO/PVA and $TiO_2$/PVA nano- composite fiber webs have possible uses in functional textiles that can decompose harmful gases.

• 자원리싸이클링
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• 제22권6호
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• pp.55-63
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• 2013

본 연구에서는 전기화학법으로 생성된 염소를 산화제로 이용하여 루테늄의 침출에 대한 연구를 수행하였다. 휘발성 루테늄산화물의 손실을 막기 위해 전 시스템이 밀폐형으로 제작된다. 루테늄의 침출의 최적조건을 조사하기 위해 pH, 온도, 전해 염소 생성시 인가전류 등의 영향을 조사하였다. 염소전해생성 시스템에 산화전류를 인가하여 염소가스를 발생시키고 침출조에 공급하여 루테늄 용해에 필요한 염소화합물을 생성시켰다. 산화제인 염소화합물의 농도가 포화상태에 도달하였을 때 루테늄 분말시료를 장입하고 침출반응을 진행하였다. 일정시간 간격으로 침출액을 채취하면서 루테늄 침출농도를 분석하였다. 본 실험결과 최적조건은 pH 10, 2 A, $40^{\circ}C$로 이 때 침출률은 88% 이다.

• 자원리싸이클링
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• 제17권1호
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• pp.66-72
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• 2008

폐알칼리망간전지로부터 침출과 공침반응을 이용하여 Mn-Zn ferrite 분말을 제조하기 위한 기초실험을 수행하였다. 100g/L 광액 농도 3.0M $H_2SO_4$, $60^{\circ}C$ 및 교반속도 200 rpm의 조건에서 과산화수소 30ml를 첨가하여 얻어진 아연과 망간의 침출율은 각각 97.9%, 93.9% 이상이었으며, 침출용액을 가지고 반응시간, 반응온도, $O_2$ 가스량을 조절하며 공침반응을 진행하였다. 공침반응 결과 pH 12, $80^{\circ}C$, $O_2$ 1.3L/min, 교반속도 400 rpm의 조건에서 Mn-Zn ferrite를 저온 합성할 수 있었다. 합성된 Mn-Zn ferrite분말은 $0.143{\mu}m$의 구형 ferrite로서 80 emu/g의 포화자화값을 가지고 있었다.

• 한국포장학회지
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• 제25권2호
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• pp.31-35
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• 2019

Kimchi is a refreshing sour food which gives sour and carbonic acid taste of carbon dioxide produced during the fermentation process. So, carbon dioxide injection was tried to raise carbonic acid taste of kimchi stored in the airtight container. First, carbon dioxide injection times of a given gas supply system were determined experimentally to attain initial concentration of 80% for different solid/liquid ratios. Since carbon dioxide is dissolved in kimchi to decrease its concentration during storage, periodical carbon dioxide injection conditions were needed and determined to keep the $CO_2$ concentration above 70%. For the initial flushing to 80% $CO_2$ concentration in model system filled with water, the injection time ranged from 40 to 89 seconds for free volumes of 2-8 L. $CO_2$ injection conditions for the under-ripened storage at $10^{\circ}C$ consisted of longer time at more frequent cycles for watery kimchi than for Chinese cabbage kimchi. At $0^{\circ}C$ of subsequent ripened stage storage of watery kimchi, the periodical injection at 3 hour interval was required because of continuous dissolution of carbon dioxide. However, Chinese cabbage kimchi did not require subsequent $CO_2$ injection during the ripened state storage and needed only flushing to 80% $CO_2$ at time of the container opening and closing. These results can be used as basic information for the programmed control of $CO_2$ injection in the kimchi container system.

• 지질공학
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• 제22권3호
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• pp.253-262
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• 2012

중금속 및 유류 오염토양 정화를 위해 효율적인 토양세척법과 공정 선정을 목적으로 최적의 오염정화 설계인자를 제시하기 위한 실험적 연구를 수행하였다. 실험 분석항목은 구리, 납, 아연을 포함하는 중금속 항목과 총석유계탄화수소(TPH)인 유류 항목에 대해 흡광광도법(absorptiometric analysis), 기체크로마토그래피(gas chromatography)법을 이용하여 단계별로 분석하였다. 실험방법은 최적 세척용매(washing solution) 결정시험, 최적 세척시간(washing time) 도출시험, 최적 진탕비(dilution ratio) 결정시험 등을 통해 얻어진 결과를 토대로 계면활성제(surfactant) 첨가량별 중금속 용출영향 분석시험, 미생물 및 과산화수소 주입시험 순으로 실시하였다. 실험결과에서 세척용매인 염산 0.1 mole, 체류시간 1시간, 진탕비 1 : 3 조건에서 오염물질의 저감효과가 우수하게 나타났으며, 이들 조건을 적용하였을 때 1%의 계면활성제를 세척 용매에 첨가하였을 경우 추가적인 오염물질의 농도저감 효과를 보이는 것으로 확인되었다. 또한 미생물과 과산화수소 주입에 따른 추가적인 TPH 농도 저감이 있는 것으로 파악되었다.