• Journal of the Korean Chemical Society
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• v.53 no.2
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• pp.144-151
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• 2009

An optode for cadmium ion determination has been designed by immobilization of dithizone on triacetylcellose membrane. When the optode membrane is introduced into a real samples containing cadmium, there is a color change from green to red, making it possible to use the change in absorbance at 611 nm as the analytical signal. The sensor could be used in the range of 0.3-3 ${\mu}g\;ml^{-1}$ (2.67-26.67 ${\mu}M$) of $Cd^{2+}$ ions with a limit of detection of 0.025 ${\mu}g\;ml^{-1}$ (25 ng $ml^{-1}$). The response time of optode is within 15 min depending on the concentration of $Cd^{2+}$ ions. It can be easily and completely regenerated by dilute EDTA solution. The effect of different possible interfering species has been examined and was shown the optode has a good selectivity. The results obtained for the determination of cadmium ion in polluted soil and water samples using the proposed optode was found to be comparable with the well-established atomic absorption method.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.30 no.1C
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• pp.73-81
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• 2005

We propose an automatic modulation recognition scheme which extracts pre-defined key features from the received signal and then applies equal gain combining method to determine the used modulation. Moreover, we compare and analyze the performance of the proposed algorithm with that of decision-theoretic algorithm. Our scheme extracts five pre-defined key features from each data segment, a data unit for the key feature extraction, which are then averaged over all the segments to recognize the modulation according to the decision procedure. We check the performance of the proposed algorithm through computer simulations for analog modulations such as AM, FM, SSB and for digital modulations such as FSK2, FSK4, PSK2, and PSK4, by measuring recognition success rate varying SNR and data collection time. The result shows that the performance of the proposed scheme is comparable to that of the decision-theoretic algorithm with less complexity.

• Journal of the Korean Institute of Gas
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• v.19 no.6
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• pp.40-46
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• 2015

Stoichiometric combustion engine with Three-way catalyst had an advantage that can reduce the harmful emissions effectively. Fuel equivalence ratio controlled from engine is very important because Fuel equivalence ratio with high conversion efficiency was narrow. This study analyzed the conversion efficiency under whole range of operating area for to evaluate the performance of three-way catalyst. In order to identify the Optimum conversion efficiency, the conversion efficiency due to change the control value of fuel equivalence ratio was investigated. The result show that conversion efficiency of emissions(more than 95%) has discovered by means of fuel equivalence ratio control at each test condition. As engine power increases, optimal fuel equivalence ratio tended to increase linearly under operating conditions of similar exhaust gas temperature.

• 한국정보교육학회:학술대회논문집
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• 2021.08a
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• pp.159-165
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• 2021

Through the fourth industrial revolution and coronavirus pandemic situation, the necessity and importance of SW education are being emphasized more. However, it is difficult to achieve the effect of improving students' computational thinking skills by just 17th hour, which is organized in the 2015 revised curriculum. Moreover, due to the coronavirus pandemic situation that has continued since last year, there are environmental restrictions on the equal SW education for students at the educational site. In this study, the unplugged class using a completion robot was designed to reflect the current situation at the educational site and experience of SW education was provided to the 6th graders of J elementary school. Through the application of a class, we checked whether the unplugged class using robots affect students' perception of SW education and the use of computational thinking skills. As a result, the unplugged class using a completion robot showed that students used computational thinking to solve given problems and had a positive impact on changes in perception of SW education.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.15 no.3
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• pp.1448-1457
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• 2014

Geriatric illness is increasing with aged population ratio due to a prolonged average life span. Research studies with therapeutic approach using oriental herbs have been attempted, but the very few studies of oriental herbal tea as a healthy drink have done as a health care. This study was performed to identify the effects of oriental herbal tea on the physiological function and behavioral change of elders at geriatric facility. A quasi-experimental design using a nonequivalent control group, pre-post test was used. Total 38 of elderly population (20 of experimental group and 18 of control group) was recruited. 100mL of a type of oriental herbal tea developed for this study was given to each subject 3 times a day for 30 days (from May to June 2013). The health scan analyzer and questionnaire for behavioral change were used to measure dependent variables. The data was analyzed by SPSS/WIN 18.0. After drinking the oriental herbal tea, more significant improvement on blood circulation (t=-4.466, p<.001), liver function (t=-2.855, p=.007), brain function (t=-2.545, p=.015), bone density (t=-6.125, p<.001), blood sugar (t=-4.180, p=<.001) and emotional factor (t=2.389, p=.023) as the sub-variable of behavioral change were found in the experimental group than control group. This study shows that oriental herbal tea can be effective on the physiological function and emotional relief of the elders. Therefore the tea can be utilized as an effective intervention for the health of elders in geriatric facility.

• Child Health Nursing Research
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• v.19 no.2
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• pp.130-139
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• 2013

Purpose: In this study an examination was done of the effects of a adolescent smoking cessation motivational program on smoking temptation, internal motivation, stage of smoking cessation and quit rate. The study was done with a nonequivalent control group pretest-posttest design. Methods: Participants in the experimental group were adolescents who smoked and were referred to the program by their high school teachers. They participated in the smoking cessation motivational program for 60 minutes per session, once or twice a week for six weeks. Participants in the control group were selected from the same age group within the school and the program was provided after the posttest was completed. t-test, Mann-Whitney test, and ${\chi}^2$-test were used to analyze data. Results: The level of smoking temptation, internal motivation and stage of smoking cessation had significant change in comparison to the pretest whereas the control group did not exhibit these changes. Conclusion: The results of the study indicate that a smoking cessation motivational program for adolescents is an effective strategy to increase smoking cessation motivation in adolescents, and can be utilized as an effective intervention for adolescents who smoke.

• Proceedings of the Materials Research Society of Korea Conference
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• 2009.05a
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• pp.26.1-26.1
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• 2009

최근 반도체 세정에 있어서 지난 40년 동안 지속적으로 사용되고 있는 알칼라인 기반의 RCA 세정법은 많은 초순수 및 화학액 소모량과 세정시 불필요한 박막의 손실, 환경적인 문제로 인하여 이를 대체하고자 하는 새로운 새정액 및 세정 방법에 대한 연구가 활발하게 이루어지고 있다. 특히 초순수에 가스를 혼합하여 메가소닉을 이용한 기능수 세정은 기존 RCA 세정액의 문제점들을 해결하기 위한 세정액으로 최근 반도체 제조 공정 뿐만 아니라 Photo mask, FPD 세정 공정에서 널리 이용되고 있다. 하지만 기능수에 대한 기초적인 특성 연구와 메가소닉에 의한 세정력 변화에 대한 연구는 부족한 상태이다. 본 연구에서는 고순도의 수소가스(99.999%)를 가스 접촉기, pHasorII (Entigris, USA) 와 순환 속도의 조절이 가능한 펌프, BPS-3 (Levitronix, USA) 를 이용하여 지속적으로 초순수와 수소가스를 혼합하는 방법으로 수소수를 제조하였으며, 용존 수소 농도계, DHDI-1 (TOA-DKK, Japan)으로 수소수의 농도를 확인하였다. 0.1 MPa 압력과, 3 LPM의 수소가스 유출속도에서 최대 2.0 ppm의 수소수를 얻을 수 있었으며, 수소수의 기초 특성을 평가하기 위하여 수소 농도 변화에 따른 pH, 표면 에너지를 측정하였다. 또한 압력 변화에 따른 반감기를 측정하여 bath형태의 세정기에서 적용 가능성을 평가하였다. 수소수의 세정력은 $Si_3N_4$ 입자가 임의로 오염된 실리콘 웨이퍼를 이용하여 bath 및 매엽식 세정기에서 수소수 농도와 메가소닉 형태 및 첨가제 변화에 따른 세정효율을 기존의 SC-1 세정액과 각각 비교 평가하였다. 기능수 발생장치에서 압력이 제거된 상태에서는 평균 20분의 반감기를 갖는 것이 관찰되었고, 압력이 유지된 상태에서는 수소수의 농도가 유지되는 것을 확인하였으며, pH의 경우 수소수의 농도가 점차 증가함에 따라 감소하여 2.0 ppm의 농도에서 pH 5.3정도의 값을 나타내었다. 표면 장력은 초순수와 비교했을 때 큰 변화가 없음을 확인할 수 있었다. Bath 형태의 세정기에서 메가소닉을 인가하여 수소수의 세정효율을 측정한 결과, 같은 조건에서 실험한 초순수와는 비슷하며, SC-1보다는 낮은 세정효율이 측정되었다. 반면 매엽식 세정기에서 동등한 조건의 실험을 실시한 결과, 수소수 세정에서 첨가제에 의한 영향으로 SC-1을 대체할 수 있는 높은 입자 제거효율을 가짐을 확인할 수 있었다.

• Journal of the Korean Recycled Construction Resources Institute
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• v.9 no.4
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• pp.553-560
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• 2021

In this study, cement clinker using a pure sample and clinker using 7% coal ash were sintered at a temperature of 1050~1500℃. Changes in the content of cement minerals and changes in microstructure by sintering temperature were reviewed. The application of coal ash as a raw material for cement clinker was applicable as a source of Al₂O₃ and SiO₂. At a sintering temperature of 1350℃ or higher, the cement clinker applied with coal ash showed the same level of mineral content as compared to the cement clinker applied with pure raw material. The microstructure also showed a similar state, confirming that coal ash can be used as a raw material for cement. In XRD-Reitveld analysis, a maximum amount of Belite was produced at 1250℃. The conversion from Belite to Alite was observed from 1350℃. From 1350℃, the interstitial phase and the mineral phase presumed to be alite were distinguished. It was clearly distinguished from 1400℃. As the sintering temperature increased, the shape and boundary of the crystal phase became clear, and the size of the crystal phase was also increased.

• Journal of Sensor Science and Technology
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• v.5 no.2
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• pp.61-67
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• 1996

The growth and characterization of heteroepitaxial $Si_{1-x}Ge_{x}$ films grown by the RTCVD (Rapid Thermal Chemical Vapor Deposition) method were described. For the growth of $Si_{1-x}Ge_{x}$ heteroepitaxial layers, $SiH_{4}$ / $GeH_{4}$ / $H_{2}$ gas mixtures were used. The growth conditions were varied to investigate their effects on the Si / Ge composition ratios, the interface abruptness and crystalline properties. The experimental data shows that the misfit threading dislocation in $Si_{1-x}Ge_{x}$ / Si heteroepitaxial film of about $400\;{\AA}$ thickness was not observed at the growth temperature of as low as $650^{\circ}C$, and the composition ratios of Si / Ge changed linearly with $SiH_{4}$ / $GeH_{4}$ gas mixing ratios in our experimental ranges. In the in-situ boron doping experiments, the doping abruptness would be controlled within several hundreds ${\AA}$/decade.

• Korean Journal of Food Science and Technology
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• v.16 no.2
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• pp.228-234
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• 1984

A partial hydrolysis of soybean protein isolate was carried out by using pepsin and trypsin. The degree of hydrolysis was evaluated by chemical analysis, viscometric measurements and gel electrophoresis. The functional properties of the hydrolyzates such as flow behavior, emulsion properties and foaming properties were evaluated. A selective hydrolysis of 11S protein fraction by pepsin was observed from the SDS-PAG electrophoresis. The changes in the molecular weight distribution by different conditions of enzyme hydrolysis were evaluated. The changes in the intrinsic viscosity of the protein hydrolylate by reaction time were highly correlated to the contents of TCA soluble protein and 0.03 M $CaCl_2$ soluble nitrogen. The degree of hydrolysis ($DH_{TCA}$, $DH_{Ca}$) were used to evaluate the effect of enzyme treatment on the functional properties of the hydrolyzate. The apparent viscosity and emulsion capacity and stability of the protein solution decreased as DH increased, while the foaming capacity increased linearly with the increasing DH.