• Journal of the Korean Wood Science and Technology
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• 제25권1호
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• pp.56-64
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• 1997

Since there are three hydroxyl groups on each anhydroglucose ring of the cellulose, the renewable resources, we can get various functional papers by the chemical modification of cellulose. The reaction involving the introduction of the ${\beta}$-cyanoethyl ($-CH_2-CH_2$-CN) group into organic substances containing reactive hydrogen atoms is known as cyanoethylation. Cellulose reacts with acrylonitrile in the presence of strong alkalis in a typical manner of primary and secondary alcohols to form cyanoethyl ethers. In cyanoethylation, important factors of reaction are temperature, concentration of the NaOH, and addition rate of acrylronitrile. FT-IR spectra of cyanoethyl group was confirmed at $2250cm^{-1}$, which corresponds the introduction of aliphatic nitrile group. Effect of cyanoethyl DS(degree of substitution) on strength properties was resulted that cyanoethylated BKP of DS 0.04 appeared to be the best choice for overall strength properties. Also, excellent thermal stability in aging characteristics was obtained.

• 대한후두음성언어의학회지
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• 제9권1호
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• pp.38-42
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• 1998

It has been reported that Tonsillectomy ＆ Adenoidectomy(T & A) resulted in the change of voice by structural changes directly to the vocal track. We studied the effect of T & A on the voice of patients comparing the pre-operative to the post-operative voice. It was performed using a Computerized Speech Lab(CSL50) which is currently used as a method for voice analysis. Forty-five patients who had T＆A, aging from 3 to 42 years old, took part in studies and wert evaluated for voice changes and the degree of formant changes of four basic vowels, /a/, /i/, /o/, and /u/. They were evaluated pre-operatively and post-operatively one month later using MDVP, CSL program of CSL50. The results obtained were as follows ; In using MDVP, there were some differences between pre-operative and post-operative shimmer measures within the normal range but other acoustic measures(Fo, jitter, NHR) show no significant differences(p>0.05). F3 of /a/ and /o/ were significantly decreased(p<0.05) and F2, F3 of /i/ were increased(p>0.05) in patients who only had Tonsillectomy in doing CSL spectrogram. For the patients who had T & A, Fl and F3 of /a/, F3 of /i/, Fl, F2 and F3 of /o/ were decreased with significant increase in F1 and F2 of /i/(p<0.05).

• 대한화장품학회지
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• 제31권3호
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• pp.253-257
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• 2005

피부노화의 정도를 판정하기 위해 사용되는 주름측정법들은 객관성과 재현성의 확보가 중요한 요소이다. 최근의 경향은 주름의 형태나 깊이에 주는 영향을 최소화하기 위해 주름 측정시 피부에 직접 기계나 도구를 접촉하지 않고 측정하는 비접촉식 측정방법으로 빠르게 전환되고 있는 상황이다. 저자들은 주름측정 기술의 변천 과정을 간단히 살펴보고, 비접촉식 fringe projection 방식의 미세주름 측정기기인 PRIMOS를 중심으로 측정원리, 특징들을 접촉식 측정방법인 모사판을 이용한 방법과 비교하였다.

• 수산해양교육연구
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• 제22권4호
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• pp.576-588
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• 2010

The goal of this research was to survey a method to reinforce the efficient political function for lifelong learning when Busan metropolitan city promotes lifelong policy. To achieve this goal, the survey to reinforce the political function for lifelong education was carried out on persons in charge of lifelong education in Busan metropolitan city. The results are as follows: First, they showed high degree of perception on lifelong policy and business. Second, on a question about how much the tasks to promote lifelong education presented by our nation are needed, they answered that concrete agenda for an aging society is needed and a necessary institute to invigorate it is lifelong learning institute. Third, they answered that the policy which is necessary to be implemented as soon as possible is the development education for vocational competency, and the ratio of the perception which requires to hire education experts for life long education was high.

• 멤브레인
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• 제9권2호
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• pp.114-125
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• 1999

Poly(1-trimethylsilyl-1-propyne)(PTMSP), poly(dimethylsiloxane)(PDMS) 막 및 PTMSP-g-PDMS막 등의 균질 치밀막을 제조하여 chloroform, trichloroethylene(TCE), perchloroethylene (PCE) 등의 유기염소계 화합물에 대한 투과증발 분리성능을 평가한 결과 PCE 대해 가장 높은 선택성을 나타내었다. PTMSP 막들의 경우는 시간이 지나면서 투과특성이 현저히 감소하였으나 PTMSP-g-PDMS 막은 지속적인 투과특성을 나타내어 시간이 경과되어도 물리적 노화현상은 거의 없었다. 또한 접촉각 측정 결과 본 연구에 사용된 고분자막들은 모두 분리대상 용질에 대해 친화성을 보였으며 균질 치밀 막들에 대한 상대적 팽윤도가 클수록 신택도가 증가하였다.

• 한국구조물진단유지관리공학회 논문집
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• 제6권2호
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• pp.113-119
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• 2002

In the prestressed concrete structures, stresses are gradually redistributed with time due to the creep and shrinkage of concrete and the stress relaxation of prestressed steel. In this study a numerical procedure and computer program is developed to analyze the behavior of prestressed concrete structures considering the time-dependent properties of material. It accounts for the aging, creep and shrinkage of concrete and the stress relaxation of prestressed steel. The structural model uses two dimensional plane frame elements with three nodal degree of freedom and is analyzed based on the finite element method. Member cross section can consist of concrete, reinforcement and prestressing steel. Two different set of equations for the prediction of time-dependent material properties of concrete are presented, which are ACI, CEB-FIP. Analytical studies for different examples of prestressed concrete structures have been performed to demonstrated the capabilities and practical applicabilities of the developed program.

• 동아시아식생활학회지
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• 제20권6호
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• pp.845-852
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• 2010

This study examined the recognition and purchasing behavior about environment-friendly agricultural produce (EFAP) of housewives in Yeungnam area. The data were collected from 401 housewives by a self-administered questionnaire on April, 2010. Frequencies, t test, chi-square test, and logistic regression analysis were conducted by SPSS Windows V.17.0. The results of the survey were as follows: (1) the purchase group of EFAP showed higher degree of concern about health and recognition about EFAP than the non-purchase group, (2) knowledge scores about EFAP were very low for both the purchase and non-purchase groups, (3) levels of confidence in EFAP in the purchase group were higher than those in the non-purchase group, (4) the purchase group considered high price as the main distribution problem about EFAP, whereas the non-purchase group regarded low trust toward producers, and (5) monthly household income (below 2,000,000 won) and confidence in EFAP were the significant factors affecting EFAP.

• Bulletin of the Korean Chemical Society
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• 제34권8호
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• pp.2271-2275
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• 2013

We report on the photoelectrochemical properties of partially reduced mesoporous titania thin films. The fabrication is achieved by synthesizing mesoporous titania thin films through the self-assembly of a titania precursor and a block copolymer, followed by aging and calcination, and heat-treatment under a $H_2$ (1 torr) environment. Depending on the temperature used for the reaction with $H_2$, the degree of the reduction (generation of oxygen vacancies) of the titania is controlled. The oxygen vacancies induce visible light absorption, and decrease of resistance while the mesoporosity is practically unaltered. The photoelectrochemical activity data on these films, by measuring their photocurrent-potential behavior in 1 M NaOH electrolyte under AM 1.5G 100 mW $cm^{-2}$ illumination, show that the three effects of the oxygen vacancies contribute to the enhancement of the photoelectrochemical properties of the mesoporous titania thin films. The results show that these oxygen deficient $TiO_2$ mesoporous thin films hold great promise for a solar hydrogen generation. Suggestions for the materials design for improved photoelectrochemical properties are made.

• International Journal of Automotive Technology
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• 제8권5호
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• pp.555-562
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• 2007

The Variable Valve Timing(VVT) system for high performance is a key technology used in newly developed engines. The system realizes higher torque, better fuel economy, and lower emissions by allowing an additional degree of freedom in valve timing during engine operation. In this study, a model-based control method is proposed to enable a fast and precise VVT control system that is robust with respect to manufacturing tolerances and aging. The VVT system is modeled by a third-order nonlinear state equation intended to account for nonlinearities of the system. Based on the model, a controller is designed for position control of the VVT system. The sliding mode theory is applied to controller design to overcome model uncertainties and unknown disturbances. The experimental results suggest that the proposed sliding mode controller is capable of improving tracking performance. In addition, the sliding mode controller is robust to battery voltage disturbance.

• Journal of Electrical Engineering and Technology
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• 제2권2호
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• pp.157-164
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• 2007

Diagnosis techniques based on the dissolved gas analysis(DGA) have been developed to detect incipient faults in power transformers. Various methods exist based on DGA such as IEC, Roger, Dornenburg, and etc. However, these methods have been applied to different problems with different standards. Furthermore, it is difficult to achieve an accurate diagnosis by DGA without experienced experts. In order to resolve these drawbacks, this paper proposes a novel diagnosis method using fuzzy clustering and a radial basis neural network(RBFNN). In the neural network, fuzzy clustering is effective for selecting the efficient training data and reducing learning process time. After fuzzy clustering, the RBF neural network is developed to analyze and diagnose the state of the transformer. The proposed method measures the possibility and degree of aging as well as the faults occurred in the transformer. To demonstrate the validity of the proposed method, various experiments are performed and their results are presented.