• Asia pacific journal of information systems
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• 제22권3호
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• pp.1-27
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• 2012

Many companies have recently become interested in using social networking sites such as Twitter and Facebook as a new channel to communicate with their customers. For example, companies often offer "special deals" (e.g., coupons, discounts, free samples, etc.) to their customers who participate in promotions or events on social networking sites. Companies often make important announcements on their products or services on social networking sites. By doing so, customers are encouraged to continue to have relationships with companies on social networking sites and to recommend the companies' presence on social networking sites to other potential customers. Moreover, customers who keep close relationships with companies on social networking sites often provide the companies with valuable suggestions and feedback. For instance, Starbucks has more than 2 million followers on Twitter, and often receive suggestions and feedback for their product offerings and services from the followers on Twitter. Although companies realize potential benefits of using social networking sites as a channel to communicate with their customers, it appears that many companies have difficulty forging long-lasting relationships with customers on social networking sites. It is often reported that many customers who had followed companies on Twitter later stopped following them for various reasons. Therefore, it is an important issue to understand what motivates customers to continue to keep relationships with companies on social networking sites. Nonetheless, due attention has yet paid to this issue until recently. This study intends to contribute to our understanding on customers' intention to continue to follow companies on Twitter and to spread positive word-of-mouth about companies on Twitter. Specifically, we identify seven potential factors that customers perceive as important in evaluating their experience with companies on Twitter. The seven factors include similarity, receptivity, interactivity, ubiquitous connectivity, enjoyment, usefulness and transparency. We posit that the seven perception factors can affect the two types of satisfaction, emotional and cognitive, which can in turn influence on customers' intention to follow companies on Twitter and to spread positive word-of-mouth about companies on Twitter. Research hypotheses formulated in this study were tested with data collected from a questionnaire survey administered to customers who had been following companies on Twitter. The data was analyzed with the partial least square (PLS) approach to structural equation modeling. The results of data analysis based on 177 usable responses were generally supportive of our predictions for the effects of the seven factors identified and the two types of satisfaction. In particular, out results suggest that emotional satisfaction was strongly influenced by perceived similarity, perceived receptivity, perceived enjoyment, and perceived transparency. Cognitive satisfaction was significantly influenced by perceived similarity, perceived interactivity, perceived enjoyment, and perceived transparency. While cognitive satisfaction was found to have significant and positive effects on both continued following and word-of-mouth intentions, emotional satisfaction had a significant and positive effect only on word-of-mouth intention.

• 전자공학회논문지CI
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• 제48권2호
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• pp.127-137
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• 2011

본 논문에서는 3축 가속도 센서를 이용하여 사람이 보행 시 발생하는 센서 데이터를 획득하여 실시간 걸음 수 검출과 활동량으로 변환 가능한 웨어러블 디바이스를 개발하였다. 피험자 59명을 대상으로 트레드밀에서 호흡가스대사분석기(K4B2), Actical 그리고 본 연구에서 개발된 디바이스를 착용 후 36분 동안 테스트 프로토콜에 따라 느리게 걷기, 걷기, 빠르게 걷기, 천천히 뛰기, 뛰기, 빠르게 뛰기 등의 다양한 걸음 속력에서 테스트를 진행하였다. 3축 가속도 센서의 X, Y, Z축 출력 값을 하나의 대표 값으로 처리하는 신호벡터크기(Signal Vector Magnitude :SVM)를 사용하였다. 또한 정확한 걸음 수를 검출하기 위해 휴리스틱 알고리즘(Heuristic Algorithm :HA)을 제안하고 적응적인 임계값 알고리즘(Adaptive Threshold Algorithm :ATA), 적응적인 잠금 구간 알고리즘(Adaptive Locking Period Algorithm :ALPA)을 제안한다. 그리고 인체 활동량 측정을 위하여 가속도 센서 출력 데이터와 피험자 정보를 이용하여 에너지소비량(Energy Expenditure :EE)을 추정하는 회귀식을 도출하였다. 실험결과 제안하는 알고리즘의 걸음 수 인식률은 97.34%를 보였으며 활동량 변환 알고리즘도 Actical의 성능보다 1.61% 향상 되었다.

• Asian-Australasian Journal of Animal Sciences
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• 제28권10호
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• pp.1454-1464
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• 2015

Four methods were adopted, including the mobile nylon bag (MNB) method, modified three-step in vitro (MTS) method, original three-step in vitro (OTS) method, and acid detergent insoluble nitrogen (ADIN) estimating method, to evaluate the intestinal digestibility of rumen undegradable protein (DRUP) of 10 types of concentrates and 7 types of roughages. After correlation analysis to determine the DRUP values using the MNB, MTS, OTS, and ADIN methods, the study aimed to find out appropriate methods to replace the MNB method due to its disadvantages such as high price, long time period, and use of a duodenal T-fistula. Three dairy cows with a permanent ruminal fistula and duodenal T-fistula were used in a single-factor experimental design. The results showed that the determined DRUP values using the MNB method for soybean meal, cottonseed meal, rapeseed meal, sunflower meal, corn germ meal, corn, rice bran, barley, wheat bran, corn fiber feed, Alfalfa (Zhao dong), Alfalfa (Long mu 801), Alfalfa (Long mu 803), grass (North), Grass (Inner Mongolia), corn silage and corn straw were 98.13%, 87.37%, 88.47%, 82.60%, 75.40%, 93.23%, 69.27%, 91.27%, 72.37%, 79.03%, 66.72%, 68.64%, 73.57%, 50.47%, 51.52%, 54.05%, and 43.84%, respectively. The coefficient of determination ($R^2=0.964$) of the results between the MTS method and the MNB method was higher than that ($R^2=0.942$) between the OTS method and the MNB method. The coefficient of determination of the DRUP values of the concentrates among the in vitro method (including the MTS and OTS methods) and the MNB method was higher than that of the roughage. There was a weak correlation between the determined DRUP values in concentrates obtained from the ADIN method and those from the MNB method, and there was a significant correlation (p<0.01) between the determined DRUP values of the roughage obtained from the MNB method and those obtained from ADIN method. The DRUP values were significantly correlated with the nutritional ingredients of the feeds. The regression equation was DRUP =100.5566+0.4169CP - 0.4344SP - 0.7102NDF - 0.7950EE ($R^2=0.8668$, p<0.01; CP, crude protein; SP, soluble protein; NDF, neutral detergent fiber; EE, ether extract). It was concluded that both the MTS method and the OTS may suitable to replace the MNB method for determining the DRUP values and the former method was more effective. Only the ADIN method could be used to predict the values of the roughages but conventional nutritional ingredients were available for all of the samples' DRUP.

• 한국환경농학회지
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• 제38권4호
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• pp.273-280
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• 2019

BACKGROUND: The reclaimed lands for agricultural use managed by the Korean government is consisted of 17,145 hectares of lands under construction and 13,384 hectares of completed lands. In order to utilize these reclaimed lands as competitive agricultural complexes, the government is preparing to develop comprehensive development plans for multiple purposes. For rational land-use planning and soil management, information of the soil chemical properties is necessary. METHODS AND RESULTS: From 2013 to 2016, soil samples were collected from 85 representative sampling sites of the reclaimed lands and analyzed for soil chemical properties including electric conductivity (EC), pH, soil organic matter (SOM), and nutrients. The annual mean soil EC ranged from 5.1 to 8.3 dS m^-1 and have continued to decrease over the years (estimation equation with EC as dependent and year as independent variable was y =0.0736x² - 1.4985x + 9.8305, R² = 0.9753). The pH ranged from 7.3 to 7.6, which was higher than the optimum range (5.5~7.0) for agricultural soils. Soil organic matter (8 to 11 g kg^-1) was lower level than the optimum range (20~30 kg^-1). Available silicate (Av.SiO₂) ranged from 169 to 229 mg kg^-1, which was close to the minimum content (≥157 mg kg^-1) for rice paddy field. Available phosphate (Av.P₂O₅) content (24~39 mg kg^-1) was lower than the optimum range (80~120 mg kg^-1) for rice paddy field. CONCLUSION: For efficient agricultural use of reclaimed lands under government management, our results suggest that the application of organic matter and supplying deficient nutrients as well as desalinization is required.

• 한국인터넷방송통신학회논문지
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• 제16권4호
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• pp.31-40
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• 2016

VANET에서 차량은 사고나 예기치 못한 긴급 상황에 관한 정보를 감지하고 이 정보를 뒤따르는 차량들에게 전파함과 동시에 서버에 전달한다. 하지만 긴급메시지의 전파는 방송 전송 방식을 취하게 되고 방송메시지의 다량 발생 즉, 폭풍 현상을 유발하게 된다. 본 논문에서는 이러한 문제점을 해결코자 전파전달범위내에서 가장 먼 곳에 위한 차량을 선출하는 방법을 사용하고 특히, 수신 패킷의 SNR에 따른 송신자와의 상대적 위치를 이용한 SNR 기반 백오프 방법을 검토한다. 상대적 위치를 통해 송신자에서 가장 멀리 떨어진 노드가 상재적으로 짧은 백오프 시간을 갖고 전달 과정에 참여케 됨으로써 다른 노드들은 이를 엿듣게 되어 전달자 임무를 포기하게 된다. NS-3 VANET 시뮬레이션 환경을 구축하여 WiFi-IP 게이트웨이 기반 서비스 네트워크에 대해서 SNR 기반 백오프 방식을 포함한 긴급 메시지 전송방식들을 시뮬레이션을 수행하였다. 다른 일반 방송 방식에 비해 SNR 기반 백오프 방식이 1/20 정도 전송횟수의 감소를 보이면서도 최적의 전파지연시간과 홉 수를 통해 긴급메시지 전파능력을 보여준다.

• 농업과학연구
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• 제12권2호
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• pp.309-323
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• 1985

본(本) 연구(硏究)는 삼축압축(三軸壓縮) 조건(條件)에서 여러 제한인자(制限因子)들이 재성형(再成形)한 해성점토(海成粘土)의 응력(應力)-변형(變形)에 미치는 영향(影響)을 알기 위하여 여러가지 단계(段階)의 함수비(含水比)와 밀도(密度)및 기타(其他)의 조건(條件)을 달리하여 실내(室內)에서 임의(任意)로 재성형(再成形)한 5가지 점토시료(粘土試料)의 비배수(非排水) 삼축압축(三軸壓縮) 시험(試驗)을 하여 다음과 같은 결과(結果)를 얻었다. 1. 함수비(含水比)의 증가(增加)와 함께 변형(變形)에 대(對)한 파괴주응력차(破壞主應力差)는 적어졌다. 2. 건조밀도(乾操密度)가 커질수록 변형(變形)에 대(對)한 파괴주응력차(破壞主應力差)는 커졌다. 3. 파괴주응력차(破壞主應力差)에 대(對)한 재성형(再成形) 함수비(含水比)와 밀도(密度)의 상호작용(相互作用)의 영향(影響)은 함수비(含水比) 6.6~9.7%와 건조밀도(乾操密度) $1.50{\sim}1.55g/cm^3$에서 가장 뚜렷했다. 4. 해성점토(海成粘土)에서는 축방향(軸方向) 변형율(變形率)이 응력(應力)-변형성질(變形性質)에 미치는 영향(影響)은 뚜렷하지 않았으나, 축방향(軸方向) 변형율(變形率)이 증가(增加)함에 따라 탄성계수율(彈性係數率)은 감소(減少)하는 경향(傾向)이 나타났다. 5. 입도(粒度)의 배합(配合)이 양호(良好)한 시료(試料)에서 변형(變形)에 대(對)한 주응력차(主應力差)가 큰 값을 나타냈다. 6. 해성점토(海成粘土)의 비배수(非排水) 변형(變形)에 관계(關係)가 깊은 인자(因子)만을 골라서 응력(應力)및 변형(變形) 예측(豫測)을 위한 중회귀(重回歸) 분석(分析) 모형(模型)을 만들 수 있다.

• 한국농림기상학회지
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• 제19권3호
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• pp.130-139
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• 2017

기상청 동네예보 풍속으로부터 농작물의 강풍피해를 예측하기 위해, 방재기상관측지점 19곳의 2012년 풍속자료를 이용하여 기상청 동네예보의 3시간 간격과 동일한 0000, 0300 ${\cdots}$ 2100 시간대의 풍속과 직전 3시간 동안의 최대풍속 간의 관계를 직선회귀식으로 표현하였다. 매 3시간 마다 추정된 최대풍속 중 가장 큰 값을 일 최대풍속으로 간주하고, 이 때의 추정오차를 정규분포와 Weibull 분포 확률밀도함수로 표현하였다. 또한 일 최대풍속과 작물 피해 임계풍속 간의 편차를 추정오차 기반 확률 분포에 적용하여 확률누적값으로 풍해 '주의보'와 '경보' 단계를 설정하였다. 19지점별 최대풍속 추정 회귀계수(a, b)와 추정오차의 표준편차 및 Weibull 분포의 모수(${\alpha}$, ${\beta}$)는 공간내삽하여 분포도로 작성하고 종관기상관측지점 4곳(순천, 남원, 임실, 장수)의 격자값을 추출하였다. 이를 이용해 2012년의 일 최대풍속을 추정하고, 배 만삼길 품종의 낙과 발생 사례에서 제시된 풍속 10m/s를 낙과 임계풍속으로 간주, 풍해 주의보와 경보를 판정하였다. 그 결과, 최대풍속 추정오차를 Weibull 분포로 표현하여 풍해 위험 정도를 판정하는 것이 정규분포만을 이용하는 것보다 더 현장에 정확한 주의보를 발령할 수 있었다.

• 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.

• 한국환경과학회지
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• 제10권6호
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• pp.431-436
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• 2001

Variations in phytoplankton concentrations result from changes of the ocean color caused by phytoplankton pigments. Thus, ocean spectral reflectance for low chlorophyll waters are blue and high chlorophyll waters tend to have green reflectance. In the Korea region, clear waters and the open sea in the Kuroshio regions of the East China Sea have low chlorophyll. As one moves even closer In the northwestern part of the East China Sea, the situation becomes much more optically complicated, with contributions not only from higher concentration of phytoplankton, but also from sediments and dissolved materials from terrestrial and sea bottom sources. The color often approaches yellow-brown in the turbidity waters (Case Ⅱ waters). To verify satellite ocean color retrievals, or to develop new algorithms for complex case Ⅱ regions requires ship-based studies. In this study, we compared the chlorophyll retrievals from NASA's SeaWiFS sensor with chlorophyll values determined with standard fluorometric methods during two cruises on Korean NFRDI ships. For the SeaWiFS data, we used the standard NASA SeaWiFS algorithm to estimate the chlorophyll_a distribution around the Korean waters using Orbview/ SeaWiFS satellite data acquired by our HPRT station at NFRDl. We studied In find out the relationship between the measured chlorophyll_a from the ship and the estimated chlorophyll_a from the SeaWiFs satellite data around the northern part of the East China Sea, in February, and May, 2000. The relationship between the measured chlorophyll_a and the SeaWiFS chlorophyll_a shows following the equations (1) In the northern part of the East China Sea. Chlorophyll_a =0.121Ln(X) + 0.504, R²= 0.73 (1) We also determined total suspended sediment mass (55) and compared it with SeaWiFS spectral band ratio. A suspended solid algorithm was composed of in-.situ data and the ratio (L/sub WN/(490 ㎚)L/sub WN/(555 ㎚) of the SeaWiFS wavelength bands. The relationship between the measured suspended solid and the SeaWiFS band ratio shows following the equation (2) in the northern part of the East China Sea. SS = -0.703 Ln(X) + 2.237, R²= 0.62 (2) In the near future, NFRDI will develop algorithms for quantifying the ocean color properties around the Korean waters, with the data from regular ocean observations using its own research vessels and from three satellites, KOMPSAT/OSMl, Terra/MODIS and Orbview/SeaWiFS.

• 대한의용생체공학회:의공학회지
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• 제28권2호
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• pp.178-186
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• 2007

This study is attempted to correct an error of electronic blood pressure meter with an optical sensor. In general, for a hospitalized patient, ECG, blood pressure, oxygen saturation, and respiration are basically measured to monitor the patient's condition. Opening of a blood vessel after it is occluded by pressurizing the cuff influences the blood flow of peripheral blood vessels as well as oscillation changes in the cuff. Blood vessels are occluded and peripheral blood flow disappears at cuff pressure above the examinee's blood pressure, while blood vessels are opened and peripheral blood flow appears again at cuff pressure under the examinee's blood pressure. Then Disappear-Appear Point Length(DAPL) of peripheral blood flow can be judged with the signal of peripheral blood flow, thus is available as a factor of error correction for electronic blood pressure meter. Also, systolic or diastolic blood pressure can be corrected with Appear-Point-Pressure(APP) of cuff pressure at a point where blood flow occurs and Appear-Maximum Pressure(AMP) of cuff pressure at the maximum amplitude point of peripheral blood flow after peripheral blood flow appears again. For verification, 27 examinees were selected, and their blood value was obtained through experimental procedure of 4 stages including induction of blood pressure change. The examinees were divided into two groups of experimental group and control group, regression analysis was conducted for experimental group, and correction of a blood pressure error was verified with optical signal by applying the regression equation calculated in experimental group to control group. As an experimental result, mean of the whole measurement errors was 5mmHg or more, which did not meet the standard fur blood pressure meter. As a result of correcting blood pressure measurements with data of DAPL, APP, and AMP as drawn out of PPG signal, systolic blood pressure, mean blood pressure, and diastolic blood pressure were $-0.6{\pm}4.4mmHg,\;-1.0{\pm}3.9mmHg$ and $-1.3{\pm}5.4mmHg$, respectively, indicating that mean of the whole measurement errors was greatly improved, and standard deviation was decreased.