• The Korean Journal of Applied Statistics
• /
• v.35 no.4
• /
• pp.543-552
• /
• 2022

When frost occurs, crops are directly damaged. When crops come into contact with low temperatures, tissues freeze, which hardens and destroys the cell membranes or chloroplasts, or dry cells to death. In July 2020, a sudden sub-zero weather and frost hit the Minas Gerais state of Brazil, the world's largest coffee producer, damaging about 30% of local coffee trees. As a result, coffee prices have risen significantly due to the damage, and farmers with severe damage can produce coffee only after three years for crops to recover, which is expected to cause long-term damage. In this paper, we tried to predict frost using frost generation data and weather observation data provided by the Korea Meteorological Administration to prevent severe frost. A model was constructed by reflecting weather factors such as wind speed, temperature, humidity, precipitation, and cloudiness. Using XGB(eXtreme Gradient Boosting), SVM(Support Vector Machine), Random Forest, and MLP(Multi Layer perceptron) models, various hyper parameters were applied as training data to select the best model for each model. Finally, the results were evaluated as accuracy(acc) and CSI(Critical Success Index) in test data. XGB was the best model compared to other models with 90.4% ac and 64.4% CSI, followed by SVM with 89.7% ac and 61.2% CSI. Random Forest and MLP showed similar performance with about 89% ac and about 60% CSI.

• Journal of Communications and Networks
• /
• v.16 no.1
• /
• pp.26-35
• /
• 2014

We consider multiple-input multiple-output decode-and-forward relay systems in Rayleigh fading channels under the partial channel state information (CSI) that the channel statistics of the source-relay (SR) link and the instantaneous CSI of the source-destination and relay-destination links are known at the destination. In this paper, we propose a new near maximum likelihood (near-ML) decoder with two-level pairwise error probability (near-ML-2PEP) which uses the average PEP instead of the exact PEP. Then, we theoretically prove that the near-ML and near-ML-2PEP decoders achieve the maximum diversity, which is confirmed by Monte Carlo simulations. Moreover, we show that the near-ML-2PEP decoder can also achieve the maximum diversity by substituting the average PEP with the values that represent the error performance of the SR link.

• Journal of the Korean Dietetic Association
• /
• v.5 no.2
• /
• pp.175-181
• /
• 1999

The present study was conducted to evaluate nutrient intakes of industrial workers with hyperlipidemia and cholesterol-saturated fat indices(CSI) of their daily meals and various side dishes accompanied with alcohol. Thirty eight male subjects of 41.0$\pm$6.5 years whose average serum cholesterol and triglyceride levels were 222.9$\pm$37.7 and 282.3$\pm$139.3mg/이 were interviewed on daily intakes of foods and drinking habits including types and amounts of side dishes using 24-hour recall and questionnaire methods. Average energy habits including twenty six non-drinkers and twelve drinkers were 2365$\pm$41 and 2822$\pm$417kcal, respectively but intakes of other nutrients were not very different between two groups. Carotene intakes was, however, low in drinkers. Intakes of saturated fat, cholesterol and CSI of subjects' daily meals were 15.4$\pm$5.4g, 229$\pm$114mg and 27.1$\pm$10.4 for non-drinkers and 18.7$\pm$7.8g, 238$\pm$69mg and 30.8$\pm$9.8 for drinkers. CSI of their daily meals varied from 10 to 60 without much differences in energy values and were positively correlated with serum cholesterol levels(r=0.2606, p<0.05). Average alcohol intakes obtained from subjects' drinking habit was 89.5$\pm$46.8g per day and major side dish was roasted beef giving 660$\pm$234kcal of energy and 24.3$\pm$8.0 of CSI. From the present study, it is concluded that industrial workers are more prone to have hyperlipidemic diets due to alcohol. To improve their diet and health, an appropriate nutrition education should be necessary and CSI of various Korean foods and meals can be used as handy self-control education tool.

• Journal of information and communication convergence engineering
• /
• v.9 no.2
• /
• pp.193-196
• /
• 2011

Transmit antenna selection techniques are prominent since they exploit the spatial selectivity at the transmitter side. In the literature, antenna selection techniques assume full knowledge of the channel state information (CSI). In this paper, we consider that the CSI is not perfectly known at the transmitter; however, a quantized version of the channel coefficients is fed back by the users. We employ the non-uniform Lloyd-Max quantization algorithm which takes into consideration the distribution of the channel coefficients. Simulation results show that the degradation in the BER of the system with imperfect CSI at the transmitter is tolerable, especially when the transmit diversity order is high.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.12 no.2
• /
• pp.872-877
• /
• 2011

In this paper, the new decoding algorithm of Block Turbo Codes using Channel State Information(CSI), which is estimated to compensate for the distorted signal caused by multi-path fading, is proposed in order to improve error correction capacity during decoding procedure in OFDM system. The performance of the new decoding algorithm is compared to that of the conventional decoding algorithm without using channel state information under the Rayleigh fading channel. Experimental results showed that in case of only one iteration coding gains of up to 5.0dB~9.0dB can be obtained by applying the channel state information to the conventional decoding algorithm according to the modulation methods. In addition to that, the new decoding algorithm using channel state information at only one iteration shows a performance improvement of 3.5dB to 5.0dB when compared to the conventional decoding algorithm after four iterations. This leads to reduce the considerable amount of computation.

• KSII Transactions on Internet and Information Systems (TIIS)
• /
• v.8 no.2
• /
• pp.389-405
• /
• 2014

Outdated Channel State Information (CSI) was proved to have negative effect on performance in two-way relay networks. The diversity order of widely used opportunistic relay selection (ORS) was degraded to unity in networks with outdated CSI. This paper proposed a multiple relay selection scheme for amplify-and-forward (AF) based two-way relay networks (TWRN) with outdated CSI. In this scheme, two sources exchange information through more than one relays. We firstly select N best relays out of all candidate relays with respect to signal-noise ratio (SNR). Then, the ratios of the SNRs on the rest of the candidate relays to that of the Nth highest SNR are tested against a normalized threshold ${\mu}{\in}[0,1]$, and only those relays passing this test are selected in addition to the N best relays. Expressions of outage probability, average bit error rate (BER) and ergodic channel capacity were obtained in closed-form for the proposed scheme. Numerical results and Simulations verified our theoretical analyses, and showed that the proposed scheme had significant gains comparing with conventional ORS.

• Kyungpook Mathematical Journal
• /
• v.61 no.3
• /
• pp.613-629
• /
• 2021

In this paper, we present and prove new existence and uniqueness fixed point theorems for vector operators having a mixed monotone property in partially ordered product Banach spaces. Our results extend and improve existing works on τ-φ-concave operators in the scalar case. As an application, we study the existence and uniqueness of positive solutions for systems of nonlinear Neumann boundary value problems.

• Proceedings of the PSK Conference
• /
• 2003.10b
• /
• pp.179.2-179.2
• /
• 2003

We have developed the novel one-pot synthetic method for regioselective and stereoselective N-protected amines through the reaction of various ethers with chlorosulfonyl isocyanate (CSI). Also, we found a novel technique to compare directly the stability of carbocations in the solution phase and established the stability order of the various carbocations. And we reported the cleavage of benzyl and p-methoxybenzyl protecting groups of alcohols and phenols in the presence of other functional groups using CSI. (omitted)

• Proceedings of the Korean Society for Emotion and Sensibility Conference
• /
• 2001.05a
• /
• pp.186-189
• /
• 2001

본 연구에서는 2종류의 색온도(4000 K, 2700 K)조건 하에서 작업자의 피로도를 평가하기 위하여 피험자에게 검색작업을 부가하고 주관평가 및 생리신호를 측정하였다. 주관평가는 ME(Magnitude Estimation)법의 설문지를 사용했으며, 생리신호는 ECG, 맥파, 피부전도도, 피부온도, 호흡, 뇌파를 측정하여 그중 ECG신호를 분석하였다. ECG신호 파라미터로서 IBI, BPM, 평균 BPM, LF/HF, CSI, CVI, CV-RR를 분석한 결과, 특히 CSI, CVI, CV-RR가 피로도와 상관관계가 높았다.

• KSII Transactions on Internet and Information Systems (TIIS)
• /
• v.6 no.2
• /
• pp.593-609
• /
• 2012

We propose a scheme to reduce the overhead associated with channel state information (CSI) feedback required for opportunistic scheduling in wireless access networks. We study the case where CSI is partially overheard by mobiles and thus one can suppress transmitting CSI reports for time varying channels of inferior quality. We model the mechanism of feedback suppression as a Bayesian network, and show that the problem of minimizing the average feedback overhead is NP-hard. To deal with hardness of the problem we identify a class of feedback suppression structures which allow efficient computation of the cost. Leveraging such structures we propose an algorithm which not only captures the essence of seemingly complex overhearing relations among mobiles, but also provides a simple estimate of the cost incurred by a suppression structure. Simulation results are provided to demonstrate the improvements offered by the proposed scheme, e.g., a savings of 63-83% depending on the network size.