• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2004년도 추계학술대회 논문집
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• pp.491-495
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• 2004

The industries use polymer materials for many purposes for they have many merits. The costs of these materials take up too great a proportion of the overall cost of products that use these materials as their major material. It is advantage for polymer industries to reduce these costs. The microcellular foaming process was developed in the early 1980s to solve this problem and proved to be quite successful. Microcellular foaming process uses inert gases such as $CO_2$, $N_2$. As these gases solve into polymer matrices, many properties are changed. The microcellular foaming process makes the glass transition temperature of polymers to low, and diminish the residual stress of polymer matrices. Besides, the microcellular foaming process has several merits, impact strength elevation, thermal insulation, noise insulation, and raw material saving etc. This characteristic of microcellular foaming process has influenced by cell morphology. The cell morphology means cell size and cell density. The cell morphology has influenced by many factors. The examples of factor are pressure drop rate, foaming temperature, foaming time, saturation pressure, saturation time etc. Among their factors, pressure drop rate is the most important factor for cell morphology in microcellular foaming injection molding process. This paper describes about the cell morphology change in accordance with the pressure drop rate of microcellular foaming injection molding process.

• International journal of advanced smart convergence
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• 제10권2호
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• pp.79-85
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• 2021

Speech recognition technology refers to a technology in which a computer interprets the speech language spoken by a person and converts the contents into text data. This technology has recently been combined with artificial intelligence and has been used in various fields such as smartphones, set-top boxes, and smart TVs. Examples include Google Assistant, Google Home, Samsung's Bixby, Apple's Siri and SK's NUGU. Google and Daum Kakao offer free open APIs for speech recognition technologies. This paper selects three APIs that are free to use by ordinary users, and compares each recognition rate according to the three types. First, the recognition rate of "numbers" and secondly, the recognition rate of "Ga Na Da Hangul" are conducted, and finally, the experiment is conducted with the complete sentence that the author uses the most. All experiments use real voice as input through a computer microphone. Through the three experiments and results, we hope that the general public will be able to identify differences in recognition rates according to the applications currently available, helping to select APIs suitable for specific application purposes.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 1994년도 Proceedings of the Korea Automatic Control Conference, 9th (KACC) ; Taejeon, Korea; 17-20 Oct. 1994
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• pp.60-65
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• 1994

In this study, the dynamic characteristics of a turbine-meter-type flowmeter is investigated by making use of the remote instantaneous flow rate measurement method (RIFM). The results of the frequency response test indicated that the gain of the flow rate of the turbine-meter-type flowmeter relative to the flow rate of the RIFM was nearly unity up to 40Hz and the phase lag of the flow rate became 90 degrees at 70Hz.

• 한국IT서비스학회지
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• 제17권1호
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• pp.121-134
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• 2018

Massive Open Online Course (MOOC) is online education that anyone can register for free and has internet access. MOOC is also called Education Revolution and is spreading rapidly all over the world. Although recent MOOC high-quality classes may enhance the value of MOOC, MOOC learning still needs much research. Since MOOC has low learning completion rate and continuous use rate, various studies on the reasons that learners give up at the beginning of learning have not been tried yet This research is studied for the continuous intention of use of MOOC applying self-determination theory and learning flow theory based on technology acceptance model. In particular, the research are conducted for cultural difference in continuous usage of MOOC between Korean and Chinese. The research results show that self-determination theory applying perceived autonomy, perceived competence, and perceived relatedness and learning flow is useful to explain continuous use of MOOC. The research also shows that Hofstede theory works well in explaining the cultural difference between Korea and China in continuous usage of MOOC. The result shows that korean is more influenced by perceived external motivation like perceived usefulness and chinese is more influenced by internal motivation like learning flow in continuous use of MOOC.

• 한국치위생학회지
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• 제22권6호
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• pp.513-520
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• 2022

Objectives: The objective of the study was to investigate the factors related to non-use of interdental care products (ICP) in adolescents. Methods: The 2019 Korean Youth Risk Behavior Web-based Survey was used, examining 57,303 subjects. Complex-sample chi-square test and logistic regression analyses were performed to identify differences in ICP according to sociodemographic characteristics and oral health behavior and to determine the factors related to non-use. Results: The ICP non-use rate was 70.9%. Factors related to the non-use of ICP were middle or low economic status (OR=1.367 and 1.677). The other significant variables were less than one tooth brushing per day (OR=1.542), no scaling within 12 months (OR=1.631), and receiving dental treatment either once or two times or more (OR=1.757 and 2.195). Conclusions: To increase the ICP usage rate, continuous attention is needed from schools and families in addition to interventions at the national level.

• 한국농공학회논문집
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• 제50권3호
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• pp.91-104
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• 2008

This study developed the WSM (weighted scenario method)-AHP method that can optimize the weighting value for multi-criteria to make GIS grid-based potential surface. The potential surface has been used to simulate urban expansion using distributed cellular automata model and to generate land-use planning as basic data. This study formulated the WSM-AHP method in mathematically and applied to test region, Suwon city, which located on south area from Seoul. WSM-AHP method generates potential map for each pair of weighting value for all criteria, which one criterion is weighted with high weighting value and the others use low weighting value, considering that the summation for all criteria weighting values should be "1". The potential change rate to the step of weighted scenario for weighting value of criteria is standardized like AHP intensity matrix in this study. From the standard potential change rate, WSM-AHP intensity matrix is completed, and then the optimal weighting value is calculated from the maximum eigenvector of the WSM-AHP matrix, according to the new WSM-AHP method developed in this study. The applied results of new method showed that the optimal weighting value from WSM-AHP is more resonable than the general AHP specialists' evaluation for weighting value. The another new finding of this study is to suggest the deterministic approach to optimize the weighting value for the distributed CA model, which is used to find new city area and to generate rational land-use planning.

• 한국농업기계학회:학술대회논문집
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• 한국농업기계학회 2000년도 THE THIRD INTERNATIONAL CONFERENCE ON AGRICULTURAL MACHINERY ENGINEERING. V.III
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• pp.662-669
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• 2000

Based on the viscous flow characteristics of gas through capillary tube, a simple and low cost system was developed for controlling gas concentration for use in C.A experiments. The gas flow rate through capillary tube had a linear relationship with pressure, $(length)^{-1}$ and $(radius)^4$ of capillary tube, which agreed well with Hagen-Poiseuille's law. The developed system could control the gas concentration in storage chamber within ${\pm}0.3%$ deviation compared to the preset concentration. The required time for producing target gas concentration in storage chamber was exactly predicted by the model used in this study, and it required much longer time than the calculated time which divided the volume of chamber by flow rate. Therefore, for producing target gas concentration as quickly as possible, it needs to supply higher flow rate of gas during the initial stage of experiment when gas concentration in storage chamber has not reached at target value. It appeared that the developed system was very useful for C.A experiments. Because one could decide a desired flow rate by the prediction model, control flow rate freely and easily by changing pressure in the pressure-regulating chamber and the accuracy was high.

• 생명과학회지
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• 제33권8호
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• pp.639-650
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• 2023

가열담배(heated tobacco products, HTPs) 에어로졸 내 유해 성분들의 수준은 담배 연기와 비교해 현저히 낮은 것으로 보고되었지만, HTPs 사용이 담배 흡연과 연관된 심혈관 위험을 완화할 수 있는지는 불분명하다. 현재 연구는 습관성 흡연자들을 대상으로 담배 흡연에서 HTPs 사용으로의 단기간 전환이 심장 자율신경조절(cardiac autonomic regulation, CAR)에 미치는 영향을 탐색하기 위한 목적으로 수행되었다. 건강한 20대 남성 흡연자 7명은 5일 동안 담배 흡연(cigaette smoking, CS), 3가지 서로 다른 HTPs 사용(IQOS use, IQ; lil SOLID use, LS; lil HYBID use, LH) 혹은 흡연 중단(non-smoking, NS)으로 구성된 개방표지, 무작위 교차설계 시험을 완료했다. 각 세션은 1주의 세척 기간으로 분리되었으며, 세션당 할당된 제품 사용 전과 사용 후 24, 48, 72, 96 및 120시간에서 생체 이물[CO (carbon monoxide) and COHb (carboxyhemoglobin)], 혈류역학적 변인(systolic and diastolic blood pressure) 및 CAR 조절을 반영하는 HRV (heart rate variability) 지표들의 수준이 평가되었다. 호기 CO 및 COHb 수준은 NS에서만 통계적으로 유의하게 감소했다. 모든 세션 내 혈류역학적 변인에서 통계적 변화는 없었다. 그러나r HRV 스펙트럼 분석에서 lnHF (log-transformed high frequency, lnHF)는 NS를 포함한 IQ와 LS에서 유의하게 증가하였으며, HFnu (normalized HF)는 NS와 LH에서 통계적으로 증가하였다. lnHF와 HFnu는 각각 세션 간 시간에 따른 유의한 상호작용효과를 나타냈다. 현재 연구는 습관성 흡연자들에게서 HTPs 사용으로의 단기간 전환이 담배 흡연에 의한 심장 미주신경 긴장도 저하를 개선하여 CAR에 영향을 미칠 수 있음을 시사한다.

• 한국방송∙미디어공학회:학술대회논문집
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• 한국방송공학회 1995년도 학술대회
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• pp.109-112
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• 1995

A rate control strategy in the MPEG is critical to the quality of the reconstructed image sequence. In this paper, were propose a rate control algorithm which can improve the coding performance for a given bit constraint. The proposed algorithm use the distortion-rate curve for the fine adjustment of the quantization scaling factor of each region. This algorithm can also handle the problem due to scene change effectively. It can be easily applicable to existing MPEG coders. Simulation results show that the performance for the algorithm is better than the rate control algorithm in the MPEG-2 TM5.

• 한국콘텐츠학회:학술대회논문집
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• 한국콘텐츠학회 2015년도 춘계 종합학술대회 논문집
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• pp.17-18
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• 2015

To improve urban safety there is an increasing social need for environmental design against crime, which is defined as the creation of inconvenient environments or situations for criminal offenders. By using a cluster analysis, we aimed to clarify crime occurrence patterns from the perspective of land-use. Osaka Prefecture was chosen as the study area because it has the highest crime rate in Japan. The results revealed that there are six patterns of crime occurrence, and that cities of medium-level of mixed land-use have the lowest crime rates.