• 한국응용과학기술학회지
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• 제34권1호
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• pp.83-90
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• 2017

Garment skin leather 표면 코팅에 사용된 폴리우레탄 수지는 polyethylene glycole(PEG)의 함유를 [NCO]/[OH] mole % 비로 달리하면서 합성하였으며, 합성된 폴리우레탄 수지의 기계적 특성은 SEM, FT-IR, UTM 등을 이용하여 측정하였다. 비이온성을 띄고 있는 PEG(poly ethylene glycol)의 [NCO]/[OH] mole % 비가 증가함에 따라 내굴곡성(건식, 습식)의 변화는 없었으며, 내마모도, 인장강도수치가 낮아짐을 알 수 있었다. 반대로 연신율 물성은 증가함을 알 수 있었다. 점도 변화 측정 결과에는 PEG의 [NCO]/[OH] mole % 증가에 따라 점도가 묽어짐을 알 수 있었다.

• 한국염색가공학회지
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• 제30권2호
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• pp.90-97
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• 2018

Hydrophilic reactive hot-melt polyurethane adhesive(HRHA) using a hydrophilic polyol having different molecular weight and NCO index was synthesized. This HRHA was synthesized using Polyethylene glycol(PEG) as a hydrophilic polyol, Polypropylene glycol(PPG) and Polycaprolactone diol(PCL) as hydrophobic polyols, and Methylene diphenyl diisocyanate(MDI) as an isocyanate. The changes in IR spectrum, viscosity and thermal properties of HRHA with different PEG molecular weights and NCO index were investigated, and the tensile strength and elongation of the HRHA casting film and the peel strength, moisture permeability and water pressure of the HRHA coated fabric were confirmed. In this experiment, as the molecular weight of PEG and NCO index increased, the adhesive strength, tensile strength, elongation and moisture permeability was increased but viscosity and Tg was decreased.

• Elastomers and Composites
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• 제55권1호
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• pp.13-19
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• 2020

4,4'-Methylenebis(2-chlorobenzenamine) (MOCA)-free fast curing polyurethanes were prepared. In this study, the processibility of a fast curing polyurethane system was characterized by assessing the pot life. The obtained pot life of the polyurethane was 6-8 s, indicating that this prepolymer-curative system is appropriate for ribbon flow casting. The influence of the NCO index on the viscosity and mechanical properties was evaluated. The viscosity, tensile strength, tear strength, and hardness of the as-prepared polyurethanes showed an increasing trend, with an increase in the NCO index, whereas the elongation at break increased initially and then decreased with an increase in the NCO index. The gel fraction and crosslink density showed a direct correlation with the NCO index, which substantiated the improved mechanical properties at the higher NCO index. The coefficients of friction and abrasion deteriorated with an increase in the NCO index.

• Bulletin of the Korean Chemical Society
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• 제35권3호
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• pp.758-764
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• 2014

Femtosecond vibrational spectroscopy was used to measure the vibrational population relaxation time ($T_1$) of different anions bound to ferric myoglobin ($Mb^{III}$) and hemoglobin ($Hb_{III}$) in $D_2O$ at 293 K. The $T_1$ values of the anti-symmetric stretching (${\nu}_1$) mode of NCS in the $NCS^-$ bound to $Mb^{III}$ ($Mb^{III}$NCS) and $Hb_{III}$ ($Hb_{III}$NCS) in $D_2O$ are $7.2{\pm}0.2$ and $6.6{\pm}0.2$ ps, respectively, which are smaller than that of free NCS. in $D_2O$ (18.3 ps). The $T_1$ values of the ${\nu}_1$ mode of NCO in the $NCO^-$ bound to $Mb^{III}$ ($Mb^{III}$NCO) and $Hb_{III}$ ($Hb_{III}$NCO) in $D_2O$ are $2.4{\pm}0.2$ and $2.6{\pm}0.2$ ps, respectively, which are larger than that of free $NCO^-$ in $D_2O$ ($1.9{\pm}0.2$ ps). The smaller $T_1$ values of the ${\nu}_1$ mode of the heme-bound NCS suggest that intramolecular vibrational relaxation (VR) is the dominant relaxation pathway for the excess vibrational energy. On the other hand, the longer $T_1$ values of the ${\nu}_1$ mode of the heme-bound NCO suggest that intermolecular VR is the dominant relaxation pathway for the excess vibrational energy in the ${\nu}_1$ mode of $NCO^-$ in $D_2O$, and that intramolecular VR becomes more important in the vibrational energy dissipation of the ${\nu}_1$ mode of NCO in $Mb^{III}$NCO and $Hb_{III}$NCO.

• 공업화학
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• 제9권7호
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• pp.1079-1084
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• 1998

우레탄 생성반응의 동역학을 조사하기 위해 지방족 이소시아네이트인 4,4'-dihexyl methane diisocyanate($H_{12}MDI$)와 1 관능기 알코올인 n-hexanol간의 반응을 실험적 측정과 수학적 모델링을 통해 연구하였다. 실험은 dibutyltin dilaurate(DBTDL)을 촉매로, 톨루엔을 용매로 온도, 촉매농도, [NCO]/[OH] 비 등을 변화시키면서 실시하였고, 반응동역학은 NCO기와 OH기의 반응에 의한 우레탄 생성반응 및 NCO기와 우레탄간의 반응에 의한 allophanate 생성반응 등 2가지 2차반응식으로 모사하였다. 반응속도상수는 Runge-Kutta 4th order 방법에 의한 전산모사방법으로 계산하였다. 대부분의 조건에서 실험치와 계산치가 잘 일치하여 본 연구에서 제안하는 반응 모델과 속도상수 계산방법이 적절함을 알 수 있었다. 또한 NCO기 90% 전환율에서 allophante/urethane의 비를 계산하였는데 대부분의 조건에서 20% 이상의 높은 값이 얻어져 allophanate 생성반응이 우레탄 물성에 중요한 영향을 미칠 수 있음을 알 수 있었다.

• 융합보안논문지
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• 제14권3_1호
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• pp.71-77
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• 2014

육군본부와 협약체결된 부사관과 학생들은 군부대 교육환경 및 교육진행 방법을 실습하고 병영실습훈련을 통한 부사관에 대한 의식 고취와 미래 군 간부의 자긍심을 습득하고자 연 1회 병영실습훈련을 실시하고 있다. 교육의 중점으로는 안보의식과 부사관 자긍심 고취, 병 기본훈련 숙달, 군인기본자세 확립에 두고 있다. 병영훈련실습이 만족스러워야만 부사관으로 임관하고자 하는 욕구가 강해진다. 부사관과 학생들의 교육만족은 미래 부사관으로서의 목표를 명확히 해주는 것이며 교육생의 욕구와 기대에 부응한 결과가 임관으로 이어질 때 병영훈련실습에 대한 의미가 있는 것이다.

• The Journal of Asian Finance, Economics and Business
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• 제7권2호
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• pp.309-316
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• 2020

This study aims to measure the relationship between corporate social responsibility (CSR) and affective commitment (ACO), normative commitment (NCO), and organizational performance in food processing enterprises (FPEs) in the Mekong River Delta, Vietnam. To test the initial model proposed in this paper, a total of 422 owners, directors and managers of FPEs were interviewed from some provinces in the Mekong River Delta. The method of exploratory factor analysis (EFA) is initially employed, then confirmatory factor analysis (CFA) and structure equation modelling (SEM) are used. The results of SEM showed that higher affective commitment was correlated with normative commitment. The results showed that four aspects of CSR toward employees, customers, environment and legal are significant factors. As a result, ACO and NCO act as mediators between CSR and organizational performance. This finding provides strong evidence of the important role of CSR to support positive impacts on ACO, NCO, and orgazational performance (OP). In addition, the success of the organizational performance is also found by contributions of CSR and NCO to its changes. Although ACO does not directly affect performance, it has a positive effect on the NCO. Therefore, it is necessary to enhance the implementation of CSR to promote implementation of organizational commitments.

• 한국기계가공학회지
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• 제7권3호
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• pp.61-66
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• 2008

For the production of urethane prepolymer, the effect of process parameters such as diisocyanate MDI and polyol TDI was tested. In this paper, design of experiments has been adopted for studying the effect of the process parameters on the improvement of NCO and viscosity of pre-polymer. As a result of comparison of different parameters, the effect of polyol was stronger than that of isocyanate in comparison of reactivity according to the amounts of isocyanate and polyol. Especially, NCO and viscosity of pre-polymer affected a product safety.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2000년도 추계종합학술대회 논문집(1)
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• pp.85-88
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• 2000

In order to resolve problems according to the phase error in QPSK demodulator of the digital communication systems. The demodulator requires carrier recovery loop which searches for the frequency and phase of the carrier. In this paper the complexity of implementation is reduced by the reduction into half of the number of the multiplier in filter structure of the conventional carrier recovery loop, and as the drawback of NCO of the conventional carrier recovery loop wastes a amount of power for the structure of lookup table , We designed the structure of combinational logic without the lookup table. In the comparison with dynamic power of the proposed NCO, the power of NCO with the lookup table is 175㎼, NCO with the proposed structure is 24.65㎼. As the result, it is recognized that about one eight of loss power is reduced. In the simulation of carrier recovery loop designed QPSK demodulator, it is known that the carrier phase is compensated.

• Macromolecular Research
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• 제14권6호
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• pp.634-639
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• 2006

Waterborne polyurethane (WBPU) adhesive with varying amounts of dimethylol propionic acid (DMPA) was synthesized by prepolymer process and blended with polyisocyanate hardener. The mean particle size of the WBPU dispersion decreased with increasing DMPA content. $^1H$ NMR spectroscopy confirmed the formation of allophanate bonds and biuret bonds due to the reaction of hardener NCO with urethane/urea groups. The optimum NCO content with the greatest adhesive strength was dependent on the total content of urethane/urea groups in the WBPU molecules. The optimum NCO content increased with increasing number of urethane groups (DMPA content). The adhesion strength of WBPU adhesives was maximized at a molar ratio of hardener NCO to urethane/urea of about 0.28.