• 한국구조물진단유지관리공학회 논문집
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• 제18권1호
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• pp.84-92
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• 2014

본 연구는 조강시멘트와 경화촉진제를 사용하여 조기강도 발현의 메커니즘을 분석하는 것이 목적이다. 연구결과 경화촉진제는 시멘트와의 수화반응시 $Ca(OH)_2$의 촉진시키는 것을 TG/DTA 실험을 통하여 검정하였다. 압축강도 측정결과 경화촉진제의 사용량이 증가 할수록 초기압축강도가 증가하는 것을 알 수 있었다. 또한 미소수화열 측정결과 경화촉진제는 시멘트의 성분중 $C_3S$의 수화반응을 촉진시키는 것으로 나타났다. XRD분석결과 재령별 수화생성물을 확인할 수 있었으며 경화촉진제의 사용량이 증가할수록 수화물들의 피크점이 높게 나타나는 것을 알 수 있었다. SEM찰영을 한 결과 촉진제의 첨가량에 따라 $Ca(OH)_2$의 생성과 재령에 따라 C-S-H의 형상을 관찰할 수 있었다. 따라서 본 연구에서 사용된 경화촉진제는 초기강도발현 시키는 것에 대해 효과적인 것을 확인 할 수 있었다.

• 한국결정성장학회지
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• 제9권1호
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• pp.119-125
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• 1999

본 연구는 싸이클론 반응로에서 $FeS_{2}$의 반응 특성에 관한 조사를 연구하였다. 수학적인 모형도로 이 반응로에서 $FeS_{2}$의 oxidation과 suifation 등을 전개하엿다. 모형은 $FeS_{2}$에서 chemical control shrinking core로서 그리고 ${Ca(OH)}_{2}$에서 fluid film control shrinking core로서 가정하였으며 수식으로서 발전시켰다. 본 실험은 이 반응 파라메터들의 영향에 연구로서 진행하였으며 즉 반응로의 온도변화, $FeS_{2}$의 입자크기, 공기 주입비율, 시료 주입비율, 그리고 $FeS_{2}$와 ${Ca(OH)}_{2}$ 비율 등이다. Oxidation과 Sulfation에 의한 반응물들은 화학적 및 물리적으로 특성을 기술하였다.

• 대한화학회지
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• 제32권5호
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• pp.416-421
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• 1988

메탄올-아세토니트릴 혼합 용매계에서 할로겐화 벤질(파라 치환된 브롬화 벤질과 요오드화 벤질)과 피리딘 사이의 친핵성 치환반응을 속도론적으로 연구하여 반응메카니즘을 밝혔다. 치환기 상호 작용 계수 ${\rho}_{XY}$값으로 부터 할로겐화 벤질과 피리딘 사이의 반응은 전이 상태에서 dissociative S$_N$2 메카니즘으로 진행되고 있음을 알 수 있었다. Hammett ${\rho}$(${\rho}_X$, ${\rho}_Y$) 값, Br${\o}$nsted ${\beta}_N$값, 분광 용매화 관계식의 계수 a, s 및 a/s 값을 이용하여 비교하였다. PES 모형과 QM 모형의 분석결과 QM 모형 해석에 잘 적용 됨을 알수 있었다.

• 한국잠사곤충학회지
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• 제38권2호
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• pp.168-174
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• 1996

Dyeing on silk with vat dyes which shows good color fastness at strong alkaline conditions were newly examined. The optimum conditions of dyeing bath to prevent the damage on the tensile strength and elongation were sodium hydroxide(NaOH) 10g/l, sodium hydrosulfite(Na2S2O4) 20~22 g/l, for 30 min at 5$0^{\circ}C$. The color yield of silk fabrics was increase according to the concentration of NaOH and Na2S2O4, but decreased at higher concentration than that of NaOH 10g/l and Na2S2O4 22g/l. The vat dyeings showed excellent color fastness against washing and light, compared with the conventional dyeings.

• Archives of Pharmacal Research
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• 제28권4호
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• pp.458-462
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• 2005

The water content of skin was determined using a FT near infrared (NIR) spectrometer. NIR diffuse reflectance spectra were collected from hairless mouse, in vitro, and from human inner arm, in vivo. It was found that the variation of NIR absorbance band 1450 nm from OH vibration of water and 1940 nm from the combination involving OH stretching and OH deformation, depending on the absolute water content of separated hairless mouse skin, in vitro, using the FT NIR spectrometer. Partial least squares regression (PLSR) was applied to develop a calibration model. The PLS model showed good correlation. For practical use of the evaluation of human skin moisture, the PLS model for human skin moisture was developed in vivo on the basis of the relative water content of stratum corneum from the conventional capacitance method. The PLS model predicted human skin moisture with a standard errors of prediction (SEP) of 3.98 at 1130-1830 nm range. These studies showed the possibility of a rapid and nondestructive skin moisture measurement using FT NIR spectrometer.

• 한국가시화정보학회:학술대회논문집
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• 한국가시화정보학회 2006년도 추계학술대회 논문집
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• pp.135-140
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• 2006

The stabilization mechanism of turbulent, lifted jet flames in a non-premixed condition has been studied experimentally. The objectives are to explain the phenomenon of a liftoff height decreasing as increasing fuel velocity and to reveal the mechanisms of flame stability Hydrogen was varied from 100 to 300 m/s and a coaxial air was fixed at 16 m/s with a coflow air less than 0.1 m/s. The technique of PIV and OH PLIF was used simultaneously with CCD and ICCD cameras. It was found that the liftoff height of the jet decreased with an increased fuel jet exit velocity. The leading edge at the flame base was moving along the stoichiometric line. Finally we confirmed that the stabilization of lifted hydrogen diffusion flames is related with a turbulent intensity, which means combustion is occurred where the local flow velocity is equal to the turbulent flame propagation velocity.

• 대한화학회지
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• 제62권5호
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• pp.344-351
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• 2018

이 연구에서는 기체 상태 페난트렌, 페난트렌올, 페난트레닐 라디칼, 하이드록실 페난트렌 라디칼에 대한 IR 스펙트럼을 BLYP/6-311++G(d,p)법을 사용하여 얻었다. 이 스펙트럼들을 비교함으로써 ${\cdot}OH$에 의한 페난트렌의 분해 반응 경로를 동정하는데 IR 스펙트럼 측정이 유용하게 사용될 수 있음을 볼 수 있었다. IR 스펙트럼에서 H 원자 제거 과정은 CH의 out-of-plane 굽힘 진동 영역인 $650{\sim}850cm^{-1}$, ${\cdot}OH$ 첨가 과정은 CH 신축 및 굽힘 진동 영역에서 용이하게 확인 할 수 있음을 알 수 있었다. 또한 5종의 페난트렌-n-올 (n = 1, 2, 3, 4, 9) 모두에 대하여 얻어진 IR 스펙트럼 역시 여기에 주어졌다.

• 패션비즈니스
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• 제11권4호
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• pp.101-110
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• 2007

Since cotton fabrics with ripple finish treatment form wavy furrows on the surface or bumpy patterns, air circulation during wearing is good and the fabric is cool to the touch. The finishing principle is based on the mercerization, which utilizes the fact that cotton fibers contract in a concentrated NaOH solution. In this study, as fabric specimens, cotton fabrics with yarn counts of 40's, 60's and 80's were used. Concentrations of the NaOH solutions were 15%, 25%, and 35%. After dyeing fabrics using Rubia akane nakai, color and other properties were measured. As the concentration of the NaOH solution increased, the fabric became thicker and denser, and the number of occurrence of the prominence and depression per unit length became larger. The color of the region contracted by ripple finish became darker after dyeing, while the color of the untreated region became lighter, which enhanced the cubic effect of the ripple finish. As the count of the cotton yarn increased, the dyeability became better. As the concentration of the NaOH solution increased, the air permeability became lower.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1996년도 추계학술대회 논문집 학회본부
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• pp.224-226
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• 1996

The purpose of this study is to research and develop $Li_xNi_{2-x}O_2$ cathode for lithium rechargeable battery. We investigated XRD, cyclic voltammetry, AC impedance response and charge/discharge cycling of $Li_xNi_{2-x}O_2$/Li cells. The cell resistance was decreased much at initial charge process from 100% SOC to 0% SOC. The discharge capacity based on $Li_xNi_{2-x}O_2$ of 1st and 15th cycles was 135mAh/g and 108mAh/g, respectively. The $Li_xNi_{2-x}O_2$/Li cell had a good properties.

• 한국마린엔지니어링학회:학술대회논문집
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• 한국마린엔지니어링학회 2005년도 후기학술대회논문집
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• pp.196-197
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• 2005

Cathodic protection is one of the successful ways to prevent corrosion of steel structures in marine environments. The unique feature of cathodic protection in seawater is the formation of calcareous deposits on cathodic metal surface. The formation principles of calcareous deposit seawater had been known for a long time. That is, cathodic reduction reactions associated with cathodic protection in seawater generate $OH^-$ at the metal surface in accordance with the formular ; 1/2 $O_2$ + $H_2O$ + $2e^-$ $2OH^-$ and $2H_2O$ + $2e^-$ ${\rightarrow}$ $H_2$ + $2OH^-$. These reactions increase the pH at the metal / seawater interface. The high pH causes precipitation of $Mg(OH)_2$ and $CaCO_3$ in accordance with the formular ; $Mg^{2+}$ + $2(OH)^-$ ${\rightarrow}$ $Mg(OH)_2$ and $Ca^{2+}$ + $HCO_3^-$ + $OH^-$ ${\rightarrow}$ $H_2O$ + $CaCO_3$. These are typically the main compounds in calcareous deposits. It obviously has several advantages compared to the conventional coatings, since the environment-friendly calcareous deposit coating is formed by the elements($Mg^{2+}$, $Ca^{2+}$) naturally present in seawater. In this study, environmental friendly calcareous deposit films were prepared on steel plates by electro plating technic in natural seawater. The influence of current density on composition ratio, structure and morphology of the coated films were investigated by scanning electron microscopy formation process of calcareous deposits films in natural seawater. And we confirmed the properties of all the films can be improved greatly by controlling the material structure and morphology with effective use of the electroplating method in natural seawater.