나이브 베이지안에 기반한 성별 예측 및 정확률 추론 기법

권태원 ( Taewon Kwon ),이의종 ( Euijong Lee ),백두권 ( Doo-kwon Baik ) 한국정보처리학회 2016 한국정보처리학회 학술대회논문집 Vol.23 No.1

사용자의 성별은 기본적이면서도 중요한 마케팅 데이터다. 그러나 최근에는 개인정보보호 강화 추세로, 회원가입 시 성별이나 나이 등의 세부 정보를 입력하지 않는 간편 가입이 많아졌다. 이러한 입력되지 않은 정보 추출을 위해 성별 예측 연구의 필요성이 증가되었다. 성별이 입력된 사용자의 정보를 바탕으로 성별이 입력되지 않은 사용자의 성별을 예측하는 기존 연구가 다양한 방법으로 진행되어왔고, 우수한 식별이 가능한 기법들은 이진분류기인 SVM을 기반으로 한 연구가 다수 존재한다. 그러나 SVM 알고리즘은 이진 분류만 가능하기 때문에 성별예측에 대한 정확률은 알 수가 없다. 성별예측의 정확률을 활용하면 부정확한 분류를 예방할 수 있으며 상품추천의 가중치로 사용 될 수 있다. 본 연구는 확률을 기반으로 하여 정확률을 추론 가능한 나이브 베이지안을 응용한다. 그리고 데이터 집합 사례를 균형있게 늘려주는 SMOTE기법을 이용해 클래스 불균형 문제를 개선했으며 또한 성별 예측의 특성에 맞게 노이즈를 제거하고, 성별 분류에 확정적인 아이템에 가중치를 적용했다. 더불어 제안 방법을 실제 데이터에 적용시켜 우수성을 입증하였다.

Energy Efficient Communication for Secure D2D Underlaid Cellular Networks

Kwon, Younggap,Suh, Hyunjoon,Oh, Jintaek,Hwang, Taewon IEEE 2017 IEEE Transactions on Vehicular Technology VT Vol.66 No.10

<P>We study energy-efficient secure communication in large-scale device-to-device (D2D) underlaid cellular networks, where base stations (BSs) and D2D users send their messages occupying the same spectrum while eavesdroppers (Eve nodes) overhear their transmissions. First, we consider the secure cellular network where users operate only in the cellular mode. We propose a link adaptation of the cellular network that strikes a balance between secrecy energy efficiency (SEE) and secrecy spectral efficiency (SSE) by maximizing the weighted product of SEE and SSE. Besides, we show that SSE first increases and then decreases with the BS power when the ratio of the eavesdropper (Eve) node density to the BS density is above a certain threshold while it monotonically increases when the Eve-to-BS density ratio is below the threshold. On the other hand, SEE first increases and then decreases with the BS power regardless of the Eve-to-BS density ratio. Next, we study how to deploy the secure D2D network under the existing secure cellular network while guaranteeing an acceptable secrecy performance of the cellular network. We show that the secrecy performance of the cellular network decreases with the D2D power when the Eve nodes are sparse while it first increases and then decreases when the Eve nodes are dense. Based on the result, we propose a link adaptation for the D2D network that maximizes the weighted product of SEE and SSE under the secrecy performance constraint of the cellular network. Simulation results show that the proposed link-adaptation schemes can achieve all the points on the Pareto boundary in SSE-SEE plane.</P>

Non-destructive Monitoring of Sweet Pepper Growth using a Hanging Scale and Images based on Deep Neural Networks

Taewon Moon,Dongpil Kim,Sungmin Kwon,Jung Eek Son 한국원예학회 2021 한국원예학회 학술발표요지 Vol.2021 No.10

Destructive analysis is one of the most accurate methods to monitor crop growth. However, the investigation process is time-consuming, and the growth of a specific crop cannot be continuously tracked because the target crop is destroyed. Existing non-destructive crop growth collection devices and algorithms required many formulas, sensors, and advanced simulations such as high-performance simulations. Complex requirements can make the device and algorithm less practical. The objective of this study was to propose a monitoring system for crop growth data collected using a hanging scale and a camera with deep neural networks. Sweet peppers (Capsicum annuum var. annuum) grown in a greenhouse (Suwon, Korea) were used for the experiment. Among the compared deep learning models, transformer showed adequate accuracy (R² = 0.80, RMSE = 0.12 kg) for crop fresh weight. Convolutional neural network for crop growth factors showed somewhat lower accuracy (avg. R² = 0.67). Deep learning models with transfer learning could be helpful to monitor crops with diverse cultivation conditions.

Energy-Efficient Routing and Link Adaptation for 2D Wireless Relay Networks in the Wideband Regime

Kwon, Younggap,Park, Hyunsung,Oh, Jintaek,Miao, Guowang,Hwang, Taewon IEEE 2018 IEEE TRANSACTIONS ON WIRELESS COMMUNICATIONS Vol.17 No.11

<P>We discuss the globally optimal energy-efficient design of a 2D relay network. Different from the existing routing protocols on energy saving, which finds the minimal energy route for a given data rate, the proposed algorithm jointly optimizes routing and data rate to maximize energy efficiency (EE) defined as the achievable data rate per power consumption. We propose a low-complexity algorithm to circumvent the huge complexity of the exhaustive search for the network EE maximization and prove its global optimality. Moreover, the proposed algorithm is implemented in a distributed fashion because each relay needs to send its routing information only to the relays in its adjacent tiers, which significantly reduces the signaling overhead of the centralized implementation. Our analysis on the worst-case complexity in a fading channel shows that the complexity of the proposed algorithm increases linearly while that of the exhaustive search increases exponentially as the tier index increases. Simulation results confirm that the proposed algorithm outperforms the existing routing protocols on energy saving and achieves the globally optimal network EE at a significantly lower complexity than the exhaustive search.</P>

Root Mean Square Decomposition for EST-Based Spatial Multiplexing Systems

Taewon Hwang,Younggap Kwon IEEE 2012 IEEE transactions on signal processing Vol.60 No.3

<P>We consider the transceiver design for multiple-input-multiple-output (MIMO) systems when the channel state information (CSI) is available at the transmitter as well as the receiver. First, we propose an open-loop low-complexity MIMO spatial multiplexing scheme based on the energy spreading transform (EST-SM). The EST-SM can spatially multiplex multiple data streams and iteratively detect the data streams with almost negligible interstream interference at sufficiently high SNR. Then, we propose a closed-loop precoding scheme suitable for the EST-SM called root mean square decomposition (RMSD) scheme. The RMSD precoding scheme combined with the EST-SM decomposes a MIMO channel into multiple subchannels with identical SNRs. This desired property minimizes bit error rate (BER) when different bit allocations on different subchannels, which cause a significant increase in system complexity, are not used. We show that when the EST-SM is used the RMSD scheme is optimal in BER performance and it achieves full diversity. Simulation results show that the RMSD scheme outperforms other existing techniques such as the geometric mean decomposition (GMD) scheme (Jiang , IEEE Trans. Signal Process., vol. 53, no. 10, pp. 3791-3803) and the uniform channel decomposition (UCD) scheme<SUP>1</SUP> (Jiang , IEEE Trans. Signal Process., vol. 53, no. 11, pp. 4283-4294) in BER performance.</P>

A Game With Randomly Distributed Eavesdroppers in Wireless Ad Hoc Networks: A Secrecy EE Perspective

Kwon, Younggap,Wang, Xudong,Hwang, Taewon IEEE 2017 IEEE Transactions on Vehicular Technology VT Vol.66 No.11

<P>We study energy-efficient secure communication using the combined approach of game theory and stochastic geometry in a large-scale wireless network, where legitimate transmitters (Alice nodes) and eavesdroppers (Eve nodes) are randomly distributed in space. We consider the following two scenarios according to the Eve tier's strategy: I) the Eve tier activates all its nodes to maximally eavesdrop the confidential messages of the Alice tier; and II) the Eve tier activates only a portion of its nodes to maximize its energy efficiency (EE) in eavesdropping according to the Alice tier's node activation. In Scenario I, we propose an alternating optimization scheme that maximizes the secrecy EE of the Alice tier by controlling the node-activation probability, the confidential message rate, the redundancy rate, and the number of active antennas. Simulation result shows that the proposed scheme can achieve the optimal secrecy EE. In Scenario II, we study an energy-efficient node activation game between the Alice tier and the Eve tier, where the former and the latter control their node-activation probabilities to maximize the secrecy EE and the eavesdropping EE, respectively. We show that the node activation game admits a unique Nash equilibrium. The node-activation probabilities of the Alice tier and the Eve tier at the Nash equilibrium can be used to estimate their network lifetimes, which are important information for the energy-efficient secure network design. Simulation result shows that the best-response dynamics converges to the Nash equilibrium within a few iterations.</P>

Acute Intestinal Ischemia Following Aortic Reconstruction

권태원 대한혈관외과학회 2002 Vascular Specialist International Vol.18 No.2

복부대동맥 수술 후 발생할 수 있는 급성 장허혈증(Acute Intestinal ischemia)은 매우 드물지만 일단 증상이 발생하고 장벽의 괴사를 동반하면 치사율이 높은 합병증이다. 다행히 수술 중 예방이 가능한 경우가 대부분이므로 대동맥 수술 중 장허혈의 발생을 줄이기 위해서는 세심한 수술 술기가 요구되며 만일 위험 인자를 갖고 있는 환자에서 복부 대동맥 수술 후 설사, 혈변 설명할 수 없는 백혈구 과다증, 발열, 복부 팽만, 균혈증 및 패혈증 등의 증상 및 징후가 있으면 우선 장허혈의 가능성을 염두에 두고 진단 및 치료를 시작하여야 한다.

Evaluation of the light use efficiency and water use efficiency of sweet peppers subjected to supplemental interlighting in greenhouses

Kwon Sungmin,Kim Dongpil,Moon Taewon,손정익 한국원예학회 2023 Horticulture, Environment, and Biotechnology Vol.64 No.4

In greenhouses, the higher plant density causes poor light environments inside the canopy due to the mutual shading of adjacent plants. Interlighting has been introduced as a countermeasure to compensate for the lack of light in the middle and bottom canopies. However, most studies have focused on growth and yield, not light use effi ciency (LUE) or water use effi ciency (WUE). The objective of this study was to evaluate the LUE and WUE of sweet pepper plants subjected to lightemitting diode (LED) interlighting in greenhouses. Two lighting treatments, natural light (control) and supplemental lighting with red and blue LEDs, were applied. Interlighting began 34 days after transplanting. The ratio of red and blue light to photosynthetic photon fl ux density (PPFD) was 8:2, and the total PPFD was adjusted to 71 μmol m −2 s −1 at a distance of 20 cm. The daily transpiration was measured by subtracting the drainage from the supplied nutrient solution and the weight change of the hydroponic systems. The photosynthetic rate was obtained by measuring light response curves at light intensities of 0, 50, 100, 200, 400, 600, 900, 1200, 1500, and 2000 μmol m −2 s −l . The LUE was calculated based on the simulated light interception obtained by 3D-scanned plant models and ray-tracing simulation. WUE was calculated by dividing the measured dry weight by the accumulated water consumption. Under the interlighting, the LUE increased at the canopy level due to the improved vertical light distributions. The WUE for biomass and fruit yield were higher in the interlighting treatment than in the control. These results were due to the higher increase rates of plant dry weight and fruit yield than that of water consumption by interlighting. In this study, the improvement of LUE and WUE by interlighting could be quantifi ed by optical simulation and a measurement of water consumption throughout the entire growth period.

Energy-Efficient Transmit Power Control for Multi-tier MIMO HetNets

Younggap Kwon,Taewon Hwang,Xudong Wang IEEE 2015 IEEE journal on selected areas in communications Vol.33 No.10

<P>In this paper, we study energy-efficient transmit power control for multi-tier multi-antenna (MIMO) heterogeneous cellular networks (HetNets), where each tier operates in closed-access policy and base stations (BSs) in each tier are distributed as a stationary Poisson point process (PPP). Each BS serves multiple users at a fixed distance away from it. We first study noncooperative energy-efficient power control, where each tier selfishly chooses its transmit power to maximize its network energy efficiency (EE). This is modeled by a noncooperative power control game. We prove the existence and the uniqueness of the Nash equilibrium of the game. Moreover, we analyze the effects of circuit power and BS densities of the tiers on their transmit power at the Nash equilibrium. Then, we investigate cooperative energy-efficient power control, where all the tiers cooperatively choose their transmit power to optimize their network EE. This cooperative power control is formulated as a multiobjective problem. To obtain Pareto-optimal solutions of the problem, we develop an algorithm that alternately updates the transmit power of the tiers. In addition to the transmit power, the circuit power consumption of the operating BSs and their active antennas affects the network EE. Due to the circuit power, activating all the BSs and turning on all the antennas may not be optimal in maximizing the network EE. Motivated by this observation, we also develop energy-efficient BS activation control and antenna activation control schemes. Finally, we extend the analysis to the highest signal-to-interference-plus-noise ratio (SINR) association, where each user connects to the BS that offers the highest SINR among the BSs in its tier. Simulation results show that the proposed energy-efficient designs significantly improve the network EE at the cost of small spectral efficiency loss compared with the spectral-efficient designs.</P>

The stiffness adjustable Wheel mechanism based on compliant spoke deformation

Joonhyuk Kwon(권준혁),Hyeungyu Yoon(윤현규),KangYup Lee(이강엽),Jongmyeong Lee(이종명),TaeWon Seo(서태원) 대한기계학회 2024 대한기계학회 춘추학술대회 Vol.2024 No.4