• 한국정보통신학회논문지
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• 제11권9호
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• pp.1749-1754
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• 2007

본 연구에서는 인체를 통신채널로 사용하는 PAN(Personal Area Network) 중에서 생체 센서(Bio sensor)에 적합한 인체통신 방식을 제안한다. 생체센서용 통신시스템은 인체내외의 센서에서 수집된 대량의 정보가 허리나 팔 등에 장착된 수신부로 고속 전송할 수 있어야 한다. 제안된 모뎀은 인체채널에 대한 특성을 분석하여 특성이 우수한 10MHz의 저주파 대역을 사용하며 저 전력과 소형화에 유리한 기저대역 통신방식으로 설계되었다. 설계된 모뎀은 20cm거리에서 $BER=10^{-5}$로 5Mbps까지 전송이 가능하며, $2{\times}2cm$의 초소형으로 구현하고 동작을 확인하였다.

• 한국융합학회논문지
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• 제10권7호
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• pp.169-174
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• 2019

자동차 운전석의 따뜻하고 쾌적한 요구가 증가하고 있기 때문에 난방 시트의 연구 개발이 활발히 이루어지고 있다. 본 연구에서는 세 가지의 난방 시트 모델 A, B, C를 가지고 열응력해석과 구조해석을 시행하였다. 똑같은 재질로 열해석을 함으로서, 연구 결과에서는 모델 A가 모델 B나 모델 C보다 더 좋은 열전달을 가짐을 보여주었다. 이로써 모델들이 제품의 형상에 따라 같은 재질을 가졌다고 하더라도 열전달들이 서로 다른 것을 알 수 있었다. 더 안정적인 난방을 기대하기 위해 열선을 추가하는 것은 더 좋은 난방이 될 수 있지만 제품의 가격대비 성능을 고려한 측면에서 한계가 있다. 전반적으로 모든 면에서 모델 B가 모델 A나 모델 C보다 열적으로 가장 안전하다고 사료된다. 본 연구결과에 의하여 취득한 내구성과 안정성 있는 자동차 난방 시트 제품의 설계데이터를 사용하여 자동차 운전석에 융합하여 그 예술적인 분위기를 조성할 수 있다.

• Korean Journal of Chemical Engineering
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• 제35권11호
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• pp.2172-2184
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• 2018

The production of isophthalic acid (IPA) from the oxidation of m-xylene (MX) by air is catalyzed by $H_3PW_{12}O_{40}$ (HPW) loaded on carbon and cobalt. We used $H_2O_2$ solution to oxidize the carbon to improve the catalytic activity of HPW@C catalyst. Experiments reveal that the best carbon sample is obtained by calcining the carbon at $700^{\circ}C$ for 4 h after being impregnated in the 3.75% $H_2O_2$ solution at $40^{\circ}C$ for 7 h. The surface characterization displays that the $H_2O_2$ modification leads to an increase in the acidic groups and a reduction in the basic groups on the carbon surface. The catalytic capability of the HPW@C catalyst depends on its surface chemical characteristics and physical property. The acidic groups play a more important part than the physical property. The MX conversion after 180 min reaction acquired by the HPW@C catalysts prepared from the activated carbon modified in the best condition is 3.81% over that obtained by the HPW@C catalysts prepared from the original carbon. The IPA produced by the former is 46.2% over that produced by the latter.

• 산업경영시스템학회지
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• 제45권3호
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• pp.49-56
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• 2022

ROK Navy intends to secure the Korean-type aircraft carrier in order to effectively prepare for various future security threats. In general, the Korean national competency is considered to be at the level of having an aircraft carrier, but it is unclear what scale aircraft carrier would be appropriate. In this study, the efficiency was evaluated through the relative comparison between national competency(national power, economic power) and the scale of aircraft carriers, and the optimal scale of the Korean-type aircraft carrier that could be acquired was presented. A DEA(Data Envelopment Analysis) model was applied to aircraft carriers(19 aircraft carriers in 11 countries) currently in operation and scheduled to be possessed in the world. As input variables, CINC(Composite Index of National Capability) and GDP(Gross Domestic Product), which are the most widely used as indicators of national and economic power, and as output variables, the full-load displacement, length, and width of aircraft carriers were selected. ARIMA(short-term within 5 years) and simple regression(long-term over 5 years) were used to estimate the future national competency of each country at the time of aircraft carriers acquisition. The relative efficiency score of the Korean-type aircraft carrier currently being evaluated is 1.062, and it was evaluated as small-scale aircraft carrier compared to the national competency. Based on Korean national competency, the optimal scale of the Korean-type aircraft carrier calculated by aggregating benchmark groups, is 58,308.1 tons of full-load displacement, 279.4m in length, and 68.3m in width.

• Steel and Composite Structures
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• 제45권2호
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• pp.205-218
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• 2022

Proper calculation of splitting tensile strength (STS) of concrete has been a crucial task, due to the wide use of concrete in the construction sector. Following many recent studies that have proposed various predictive models for this aim, this study suggests and tests the functionality of three hybrid models in predicting the STS from the characteristics of the mixture components including cement compressive strength, cement tensile strength, curing age, the maximum size of the crushed stone, stone powder content, sand fine modulus, water to binder ratio, and the ratio of sand. A multi-layer perceptron (MLP) neural network incorporates invasive weed optimization (IWO), cuttlefish optimization algorithm (CFOA), and electrostatic discharge algorithm (ESDA) which are among the newest optimization techniques. A dataset from the earlier literature is used for exploring and extrapolating the STS behavior. The results acquired from several accuracy criteria demonstrated a nice learning capability for all three hybrid models viz. IWO-MLP, CFOA-MLP, and ESDA-MLP. Also in the prediction phase, the prediction products were in a promising agreement (above 88%) with experimental results. However, a comparative look revealed the ESDA-MLP as the most accurate predictor. Considering mean absolute percentage error (MAPE) index, the error of ESDA-MLP was 9.05%, while the corresponding value for IWO-MLP and CFOA-MLP was 9.17 and 13.97%, respectively. Since the combination of MLP and ESDA can be an effective tool for optimizing the concrete mixture toward a desirable STS, the last part of this study is dedicated to extracting a predictive formula from this model.

• 의정연구
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• 제15권1호
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• pp.39-63
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• 2009

지난 60년간의 국회와 정부 간의 상호작용 양식을 조감해 보면 국회는 더 이상 과거 제3세계 의회 일반이 그랬던 것처럼 극소의회도 아니고 기관 자체의 존립 여부를 걱정해야 하는 임계의회도 아니다. 무엇보다도 국회의 정치적 상징 기능은 매우 괄목할만한 성장추세를 보이고 있고 이미 기관 존속 여부를 걱정해야 할 제도화 단계를 넘은지도 오래 되었다. 그러나 여전히 사회문제 해결능력에 있어서는 국회가 정부에 압도되어 있으며, 오히려 이는 일부 심화되는 경향까지 나타나고 있다. 그러나 이런 국회의 무력성을 낳는 원인이 과거 군부 권위주의 시대에 있어서는 국회 외부로부터의 수직적 통제 때문이었다고 한다면 오늘날에 있어서는 국회 내부의 수평적 이견 분출에 있다는 점이 서로 다르다. 과거 국회가 주변적 정책결정자로 전락하는 이유가 외부로부터의 억압에 의한 자율성 박탈 때문이었다고 한다면, 이제는 내부로부터 분출하는 자율권 행사의 관리능력 부족에 기인하는 바 크다. 이는 원내 정당의 무력성과 그의 파편적 리더십에 연유하는 바 적지 않다. 정당정치의 정상화는 이제 한국정치에 있어 더 이상 미룰 수 없는 선결과제가 되었다.

• Journal of Animal Science and Technology
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• 제65권5호
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• pp.939-950
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• 2023

This study was conducted to assess the impact of growing condition variables on alfalfa (Medicago sativa L.) productivity. A total of 197 alfalfa yield results were acquired from the alfalfa field trials conducted by the South Korean National Agricultural Cooperative Federation or Rural Development Administration between 1983 and 2008. The corresponding climate and soil data were collected from the database of the Korean Meteorological Administration. Twenty-three growing condition variables were developed as explaining variables for alfalfa forage biomass production. Among them, twelve variables were chosen based on the significance of the partial-correlation coefficients or potential agricultural values. The selected partial correlation coefficients between the variables and alfalfa forage biomass ranged from -0.021 to 0.696. The influence of the selected twelve variables on yearly alfalfa production was summarized into three dominant factors through factor analysis. Along with the accumulated temperature variables, the loading scores of the daily mean temperature higher than 25℃ were over 0.88 in factor 1. The sunshine duration at temperature between 0℃-25℃ was 0.939 in factor 2. Precipitation days were 0.82, which was the greatest in factor 3. Stepwise regression applied with the three dominant factors resulted in the coefficients of factors 1, 2, and 3 for 0.633, 0.485, and 0.115, respectively, and the R-square of the model was 0.602. The environmental conditions limiting alfalfa growth, such as daily temperature higher than 25℃ or daily mean temperature affected annual alfalfa production most substantially among the growing condition variables. Therefore, future cultivar selection should consider the capability of alfalfa to be tolerant to extreme summer weather along with biomass production potential.

• 한국농업기계학회:학술대회논문집
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• 한국농업기계학회 2017년도 춘계공동학술대회
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• pp.156-156
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• 2017

Most crop damages have been occurred by vermin(e.g., wild birds and herbivores) during the period between seeding and the cotyledon level. In this study, to minimize the damage by vermin and acquire the benefits such as protection against weeds and maintenance of water content in soil, immediately vinyl mulching after seeding was devised. Vinyl mulching has been generally covered with black color vinyl, that crop seeding locations cannot be detected by visible light range. Before punching vinyl, non-contact and non-destructive methods that can continuously determine the locations are necessary. In this study, a crop position detection method was studied that uses infrared thermal image sensor to determine the cotyledon position under vinyl mulch. The moving system for acquiring image arrays has been developed for continuously detecting crop locations under plastic mulching on the field. A sliding mechanical device was developed to move the sensor, which were arranged in the form of a linear array, perpendicular to the array using a micro-controller integrated with a stepping motor. The experiments were conducted while moving 4.00 cm/s speed of the IR sensor by the rotational speed of the stepping motor based on a digital pulse width modulation signal from the micro-controller. The acquired images were calibrated with the spatial image correlation. The collected data were processed using moving averaging on interpolation to determine the frame where the variance was the smallest in resolution units of 1.02 cm. For this study, the spline method was relatively faster than the other polynomial interpolation methods, because it has a lower maximum order of formulation when using a system such as the tridiagonal linear equation system which provided the capability of real-time processing. The temperature distribution corresponding to the distance between the crops was 10 cm, and the more clearly the leaf pattern of the crop was visually confirmed. The frequency difference was decreased, as the number of overlapped pixels was increased. Also the wave pattern of points where the crops were recognized were reduced.

• 대한지역사회영양학회지
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• 제15권1호
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• pp.137-148
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• 2010

This study was conducted on 175 child-care teachers, who participated in in-service education, to research the methods to improve child-care teacher's nutrition management capability for infants and children. Investigated results of child-care teachers' nutrition knowledge, dietary attitude status, and needs on nutrition education in child-care centers are as follows: The score of child-care teachers' nutrition knowledge was 10.83 points out of 15, which is about 72%. Total score increased as teachers' age but not significantly different from their career duration, since teachers who have a child-care career less than 5 years acquired 10.91 points, which is higher than 10.64 points of teachers having more than 5 years of child-care career. Teachers' average recognition to the nutrition knowledge was 90.6%, increased significantly by the older they are, and decreased according to the accumulation of their career. The average accuracy of the nutrition knowledge was 79.7%, increased in proportion to the teachers' age. The marks of child-care teachers' dietary attitude were 41.3 points (possible score range 5-50) and 83%, older teachers tended to have more desirable dietary attitude. As indicated by the increment of child-care career, the score of emotional attitude tended to be increased but which of cognitive and behavioral attitude showed a declining tendency. Nutrition information which child-care teachers were mainly interested in were correct selection of food (58.1%), obesity and weight management (52.7%), and nutrient content of food (44.9%). Nutrition education contents which child-care teachers needed were 'nutritious food and menu for child' (72.2%), 'health management of child' (69.2%) and meal management of child (40.2%). Nutrition education methods, which child-care teachers considered as of desirable ones, were cooking class of small scale (31.8%), visiting class at child-care center (26.5%). In consequence, the nutrition knowledge and dietary attitude of child-care teachers were not good and showed different issues by age and career duration. Therefore, it is requisite to intensify nutrition management courses in child-care teachers' qualification and in-service education courses which has actual necessity and suitability based on teachers' age, career, and the type of child-care center, and to disseminate these through public health centers and child-care & education information centers to pursue the efficient balance of nutrition education programs.

• Investigative Magnetic Resonance Imaging
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• 제6권1호
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• pp.41-46
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• 2002

Fourier 변환 동맥혈관 영상법(FTA)은 동맥혈류의 속도가 심장박동 주기와 동기화되어서 주기적으로 변화하는 사실에 착안하였다. Presaturation 기법에 의하여 정맥과 동맥을 분리하는 기존의 다른 혈관촬영법과는 본질적으로 다른 기술이다 따라서 생체조직의 고주파(RF) 흡수정도가 낮으며, 굽은 혈관이나 역류 현상으로부터 발생될 수 있는 어두운 띠 모양의 허상이 나타나지 않는다. 더욱이 강한 경사자기장을 사용하지 않음으로써 강한 경사자기장에 수반되는 와류현상에 의한 허상까지도 줄일 수 있는 장점이 있다. 그러나 하나의 투사 영상을 얻고, 영상 영역 내에서 혈류 유입부와 출구부의 혈류포화 현상에 의하여 신호강도가 상이한 단점이 있다. 이러한 단점들은 최근의 기술적 발전으로 극복될 수 있다. 현대 자기공명영상장치의 고속 경사자계 변화 능력으로 반복시간(TR)의 변화 없이 FTA 시퀀스에 이중 투사법을 적용할 수 있었다. 경사 고주파 전자기파(Ramped RF) 펄스를 사용하여 유입부와 출구부에서 숙임각을 달리하여 신호가 포화되는 정도를 줄여서 균일한 혈관신호를 얻을 수 있었다. 이중투사영상과 경사고주파 펄스를 사용하여 대퇴 동맥의 시상면과 관상면 투사영상을 동시에 얻고, 종래의 FTA 방식에 의한 영상보다 출구부의 혈관신호가 향상된 결과 영상을 얻을 수가 있었다.