• KSII Transactions on Internet and Information Systems (TIIS)
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• v.13 no.2
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• pp.711-732
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• 2019

Many unmanned aerial vehicle (UAV) applications have been employed for performing data collection in facilitating tasks such as surveillance and monitoring objectives in remote and dangerous environments. In light of the fact that most of the existing UAV relaying applications operate in conventional half-duplex (HD) mode, a full-duplex (FD) based UAV relay aided wireless network is investigated, in which the UAV relay helps forwarding information from the source (S) node to the destination (D). Since the activated UAV relays are always floating and flying in the air, its channel state information (CSI) as well as channel capacity is a time-variant parameter. Considering decode-and-forward (DF) relaying protocol in UAV relays, the cooperative relaying channel capacity is constrained by the relatively weaker one (i.e. in terms of signal-to-noise ratio (SNR) or signal-to-interference-plus-noise ratio (SINR)) between S-to-relay and relay-to-D links. The channel capacity can be optimized by adaptively optimizing the transmit power of S and/or UAV relay. Furthermore, a hybrid HD/FD mode is enabled in the proposed UAV relays for adaptively optimizing the channel utilization subject to the instantaneous CSI and/or remaining self-interference (SI) levels. Numerical results show that the channel capacity of the proposed UAV relay aided wireless networks can be maximized by adaptively responding to the influence of various real-time factors.

• Korean Journal of Heritage: History & Science
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• v.54 no.2
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• pp.194-215
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• 2021

Termites are important decomposers in the ecosystem. They are also economically significant structural pests. In this study, we reviewed the developments of termite control and recent research on termite management to provide information on the prevention and control of termites. In Korea, most of the damage to wooden historical buildings is caused by subterranean termites. Reticulitermes speratus kyushuensis is the main species, which is widely found throughout the country. In the early 1900s, inorganic insecticides, such as arsenic dust, were used for termite control. After the synthesis of chlorinated hydrocarbon pesticide in the 1940s, it was widely utilized and demonstrated high termite control efficacy. However, chlorinated hydrocarbon insecticides were later banned, disappearing from markets after reports emerged concerning environmental contamination and toxicity to humans. Therefore, the termite control industry sought a new termiticide; hence many pesticides were utilized for termite control. Organophosphate (1960s), carbamate (1970s), pyrethroid, and insect growth inhibitor (1980s) were newly synthesized and adopted. In the 1990s, the first commercial baits using chitin synthesis inhibitors (CSI) were developed, providing a means to eliminate an entire colony of subterranean termites around a structure. Many studies have been carried out on soil termiticides (liquid termiticides) and CSI baits to increase their efficacy, and different baits such as aboveground bait stations, fluid bait, and high-durability bait were also developed in the 2000s. In addition, the paradigm of termite control has shifted from localized treatments using soil termiticides to area-wide pest management using CSI baits to create termite-free zones and protect buildings over time. Termite infestations in wooden historical buildings in Korea have been reported since 1980, and considerable attention was drawn in the 1990s when several UNESCO world heritages such as the Jongmyo Shrine and the Janggyeong Panjeon Depositories of Haeinsa Temple were infested by subterranean termites. Since then, a survey of termite infestation in wooden architectural heritage has been conducted, and the National Research Institute of Cultural Heritage and Heritage Care Program regularly monitors those properties. Finally, we suggest termite management using primarily CSI baits, selective application of various soil treatments applied to the object, foundation soil treatment, research and development of durable termite baits, application of area-wide programs for wooden-building complexes, application of integrated termite management (ITM), and regular education for owners and managers to prevent and reduce termite damage.

• Korean Management Science Review
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• v.20 no.2
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• pp.135-149
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• 2003

Developing a proper program for customer evaluation is one of the most imminent tasks to implement CRM (Customer Relationship Management). Design of the Customer Value model is an important key to the customer evaluation progrgm. This paper proposes two models for estimating Customer Value. The first one is a Description Model for Customer Value based on customer CSI (Customer Satisfaction Index) data. This model represents as quantitative numbers what customers feel from the company or the service. The second one is a Prediction Model which employs factor analysis and regression to predict customer value. This paper exploits the two models to evaluate Customer Value as well as for customer behavior prediction.

• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 2018.06a
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• pp.88-89
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• 2018

본 논문에서는 다수의 1 차 사용자가 존재하는 무선 인지 중계 네트워크를 분석한다. 다수의 1 차 사용자들의 신호는 2 차 사용자에게 간섭으로 작용하고 2 차 사용자들의 신호 또한 1 차 사용자에게 간섭으로 작용하게 된다. 이러한 환경에서 불완전한 채널 정보를 이용하여 최적의 중계기를 선택하는 방법을 제안하고 이때의 2 차 사용자 네트워크에서의 불능 확률을 분석하였다. 또한 모의실험을 통하여 불완전 채널 정보의 상관 계수의 변화에 따른 불능 확률의 변화를 확인하였다.

• Journal of Korea Water Resources Association
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• v.57 no.3
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• pp.165-179
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• 2024

It is crucial to have a comprehensive understanding of inundation and water cycle in urban areas for mitigating flood risks and sustainable water resources management. In this study, we developed a Cellular Automata-based integrated Water cycle model (CAW). A comparative analysis with physics-based and conventional cellular automata-based models was performed in an urban watershed in Portland, USA, to evaluate the adequacy of spatiotemporal inundation simulation in the context of a high-resolution setup. A high similarity was found in the maximum inundation maps by CAW and Weighted Cellular Automata 2 Dimension (WCA2D) model presumably due to the same diffuse wave assumption, showing an average Root-Mean-Square-Error (RMSE) value of 1.3 cm and high scores of binary pattern indices (HR 0.91, FAR 0.02, CSI 0.90). Furthermore, through multiple simulation experiments estimating the effects of land cover and soil conditions on inundation and infiltration, as the impermeability rate increased by 41%, the infiltration decreased by 54% (4.16 mm/m²) while the maximum inundation depth increased by 10% (2.19 mm/m²). It was expected that high-resolution integrated inundation and water cycle analysis considering various land cover and soil conditions in urban areas would be feasible using CAW.

• Progress in Medical Physics
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• v.14 no.2
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• pp.90-98
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• 2003

Purpose : A new virtual simulation technique for craniospinal irradiation (CSI) that uses a CT-simulator was developed to improve the accuracy of field and shielding placement as well as patient positioning. Materials and Methods : A CT simulator (CT-SIM) and a 3-D conformal radiation treatment planning system (3D-CRT) were used to develop CSI. The head and neck were immobilized with a thermoplastic mask while the rest of the body was immobilized with a Vac-Loc. A volumetric image was then obtained with the CT simulator. In order to improve the reproducibility of the setup, datum lines and points were marked on the head and body. Virtual fluoroscopy was performed with the removal of visual obstacles, such as the treatment table or immobilization devices. After virtual simulation, the treatment isocenters of each field were marked on the body and on the immobilization devices at the conventional simulation room. Each treatment fields was confirmed by comparing the fluoroscopy images with the digitally reconstructed radiography (DRR) and digitally composited radiography (DCR) images from virtual simulation. Port verification films from the first treatment were also compared with the DRR/DCR images for geometric verification. Results : We successfully performed virtual simulations on 11 CSI patients by CT-SIM. It took less than 20 minutes to affix the immobilization devices and to obtain the volumetric images of the entire body. In the absence of the patient, virtual simulation of all fields took 20 min. The DRRs were in agreement with simulation films to within 5 mm. This not only reducee inconveniences to the patients, but also eliminated position-shift variables attendant during the long conventional simulation process. In addition, by obtaining CT volumetric image, critical organs, such as the eyes and the spinal cord, were better defined, and the accuracy of the port designs and shielding was improved. Differences between the DRRs and the portal films were less than 3 m in the vertebral contour. Conclusion : Our analysis showed that CT simulation of craniospinal fields was accurate. In addition, CT simulation reduced the duration of the patient's immobility. During the planning process. This technique can improve accuracy in field placement and shielding by using three-dimensional CT-aided localization of critical and target structures. Overall, it has improved staff efficiency and resource utilization by standard protocol for craniospinal irradiation.

• Journal of Korea Water Resources Association
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• v.54 no.5
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• pp.301-309
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• 2021

In this study, we tried to improve the performance of the existing U-net-based deep learning rainfall prediction model, which can weaken the meaning of time series order. For this, ConvLSTM2D U-Net structure model considering temporal consistency of data was applied, and we evaluated accuracy of the ConvLSTM2D U-Net model using a RainNet model and an extrapolation-based advection model. In addition, we tried to improve the uncertainty in the model training process by performing learning not only with a single model but also with 10 ensemble models. The trained neural network rainfall prediction model was optimized to generate 10-minute advance prediction data using four consecutive data of the past 30 minutes from the present. The results of deep learning rainfall prediction models are difficult to identify schematically distinct differences, but with ConvLSTM2D U-Net, the magnitude of the prediction error is the smallest and the location of rainfall is relatively accurate. In particular, the ensemble ConvLSTM2D U-Net showed high CSI, low MAE, and a narrow error range, and predicted rainfall more accurately and stable prediction performance than other models. However, the prediction performance for a specific point was very low compared to the prediction performance for the entire area, and the deep learning rainfall prediction model also had limitations. Through this study, it was confirmed that the ConvLSTM2D U-Net neural network structure to account for the change of time could increase the prediction accuracy, but there is still a limitation of the convolution deep neural network model due to spatial smoothing in the strong rainfall region or detailed rainfall prediction.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.42 no.2
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• pp.386-388
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• 2017

In this paper, we propose a novel protocol design for multi-subband feedback-based multicast services in LTE systems, which reduces feedback overheads with guaranteeing QoS. Through the experimental results, it is manifested that the proposed protocol is able to reduce more feedback overheads in comparison with the conventional scheme.

• Radiation Oncology Journal
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• v.17 no.4
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• pp.269-274
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• 1999

Purpose : To evaluate the Possibility of decreasing the radiation dose and to determine optimum treatment volume in intracranial germinomas. Materials and Methods : Forty five patients with pathologically-verified or presumed germinomas by a radiosensitivity test who had been treated with radiotherapy (RT) alone between 1971 and 1992 were retrospectively analyzed. The average age was 17.2 years with 68.9$\%$ of the patients being between the ages of 10$\~$20. The male and female ratio was 2.2:1. The locations of the primary tumors were at the pineal regions in 14 patients; the suprasellar regions in 12 patients; and multiple sites in 12 patients. Treatment volumes varied from a small local field (10) to the whole brain (7) or entire neuroaxis irradiation(28). All the cases after 1982 received craniospinal irradiation (CSI). Radiation doses were 41-59 Gy (median 48.5 Gy) to the primary tumor site and 19.5$\~$36 Gy (median 24 Gy) to the neuroaxis. The median follow-up period was 82 months with a range of 2$\~$260 months. Results : All the patients showed complete response after RT. Four patients sufferred from recurrence 14, 65, 76, and 170 months after RT, respectively, and two patients died with intercurrent disease. One of four recurrent cases was salvaged by re-irradiation. Therefore, a 5 and 10 year overall suNival was 95.3$\%$ and 84.7 $\%$ respectively. Five and ten year disease-free survival was 97.6 $\%$ and 88.8 $\%$ respectively. All the recurrences occurred in the patients who received local RT (3/10) or whole brain RT (1/7) with a radiation dose of 48-50 Gy. None of the patients who received CSI suffered recurrence. There was no recurrence among the 15 patients who received $\leq$45 Gy to the primary site and the 18 patients who received $\leq$24 Gy (6 patients received 19.5 Gy) to the neuroaxis. Conclusion : CSI is recommended for the treatment of intracranial germinomas. The radiation dose can be safely decreased to $\leq$45 Gy on a primay tumor site and 19.5 Gy on the spine.

• Journal of Aquaculture
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• v.13 no.2
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• pp.169-174
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• 2000

Reproductive cycle of U. unicinctus was studied from September 1998 to August 1999, using gonadosomatic index (CSI) as an indicator. In November, the CSI values were maximum for male (6.2) and female (7.0), respectively; the values were lowest for them (1.0 and 0.5) during the successive february. Subsequently, they rapidly increased and attained peak by March-April. The values decreased again in both sexes and remained unchanged until August. The index increased in October to attain the peak by November. The CSI values clearly indicated that there are two spawning events in a year, namely the first one during April-May and the second one in December. Reproductive cycle was classified into the following successive stages: in female, multipication (January~February, June ~Setember), maturation (March~April, November), spent (May and December), degeneration and resting (June and January), and in male, multiplication January ~ february, June ~September), maturation (March~April, October~November), spent (May and December) and degeneration and resting (January and June). Histological observations revealed that oocytes in the ovary matured simultaneously in November and March. At the same time, the envelopes of matured testis became thinner than those in the early stage.