• Journal of the Korean Society of Radiology
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• v.6 no.6
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• pp.455-464
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• 2012

This study suggested evaluation of approximately exposure to low-dose ionization radiation from medical images using a computed radiography (CR) system in standard X-ray examination and experimental model can compare diagnostic reference level (DRL) will suggest on optimization condition of guard about medical radiation of low dose space. Entrance surface dose (ESD) cross-measuring by standard dosimeter and optically stimulated luminescence dosimeters (OSLDs) in experiment condition about tube voltage and current of X-ray generator. Also, Hounsfield unit (HU) scale measured about each experiment condition in CR system and after character relationship table and graph tabulate about ESD and HU scale, approximately radiation dose about head, neck, thoracic, abdomen, and pelvis draw a measurement. In result measuring head, neck, thoracic, abdomen, and pelvis, average of ESD is 2.10, 2.01, 1.13, 2.97, and 1.95 mGy, respectively. HU scale is $3,276{\pm}3.72$, $3,217{\pm}2.93$, $2,768{\pm}3.13$, $3,782{\pm}5.19$, and $2,318{\pm}4.64$, respectively, in CR image. At this moment, using characteristic relationship table and graph, ESD measured approximately 2.16, 2.06, 1.19, 3.05, and 2.07 mGy, respectively. Average error of measuring value and ESD measured approximately smaller than 3%, this have credibility cover all the bases radiology area of measurement 5%. In its final analysis, this study suggest new experimental model approximately can assess radiation dose of patient in standard X-ray examination and can apply to CR examination, digital radiography and even film-cassette system.

• Journal of the Korean Society of Radiology
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• v.15 no.7
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• pp.1041-1047
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• 2021

In this study, the effective dose for frequently general radiography among the diagnostic reference level (DRL) for examinations provided by the government in Korea was evaluated using the Monte Carlo N-Particle eXtended (MCNPX) simulation tool. We were selected to evaluate for a total of 5 examination sites which included head anterior-posterior, chest (posterior-anterior, lateral), abdomen anterior-posterior and pelvis anterior-posterior. Physical conditions such as tube voltage and tube current used in MCNPX simulation were used in domestic conditions of the Korea Disease Control and Prevention Agency (KDCA). To evaluate domestic medical radiation exposure, we used the HDRK-Man computerized human phantom manufactured based on the international standard ICRP 103 that was applied to the MCNPX simulation. The phantom could represent the standard body shape of Koreans. As a results, the effective dose corresponding to the DRL based on adult males of head anterior-posterior position was 0.086 mSv, chest posterior-anterior position was 0.05 mSv, chest lateral was 0.354 mSv, abdomen anterior-posterior position was 0.548 mSv, and pelvis anterior-posterior position was 0.451 mSv.

• KIPS Transactions on Software and Data Engineering
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• v.10 no.5
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• pp.179-186
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• 2021

Manipulation of complex objects with an anthropomorphic robot hand like a human hand is a challenge in the human-centric environment. In order to train the anthropomorphic robot hand which has a high degree of freedom (DoF), human demonstration augmented deep reinforcement learning policy optimization methods have been proposed. In this work, we first demonstrate augmentation of human demonstration in deep reinforcement learning (DRL) is effective for object manipulation by comparing the performance of the augmentation-free Natural Policy Gradient (NPG) and Demonstration Augmented NPG (DA-NPG). Then three DRL policy optimization methods, namely NPG, Trust Region Policy Optimization (TRPO), and Proximal Policy Optimization (PPO), have been evaluated with DA (i.e., DA-NPG, DA-TRPO, and DA-PPO) and without DA by manipulating six objects such as apple, banana, bottle, light bulb, camera, and hammer. The results show that DA-NPG achieved the average success rate of 99.33% whereas NPG only achieved 60%. In addition, DA-NPG succeeded grasping all six objects while DA-TRPO and DA-PPO failed to grasp some objects and showed unstable performances.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.13 no.8
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• pp.3821-3841
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• 2019

Cloud radio access networks (C-RANs) have been regarded in recent times as a promising concept in future 5G technologies where all DSP processors are moved into a central base band unit (BBU) pool in the cloud, and distributed remote radio heads (RRHs) compress and forward received radio signals from mobile users to the BBUs through radio links. In such dynamic environment, automatic decision-making approaches, such as artificial intelligence based deep reinforcement learning (DRL), become imperative in designing new solutions. In this paper, we propose a generic framework of autonomous cell activation and customized physical resource allocation schemes for energy consumption and QoS optimization in wireless networks. We formulate the problem as fractional power control with bandwidth adaptation and full power control and bandwidth allocation models and set up a Q-learning model to satisfy the QoS requirements of users and to achieve low energy consumption with the minimum number of active RRHs under varying traffic demand and network densities. Extensive simulations are conducted to show the effectiveness of our proposed solution compared to existing schemes.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.18 no.1
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• pp.233-262
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• 2024

Due to the rapid evolution of vehicular ad hoc networks (VANETs), effective communication and security are now essential components in providing secure and reliable vehicle-to-vehicle (V2V) and vehicle-to-infrastructure (V2I) communication. However, due to their dynamic nature and potential threats, VANETs need to have strong security mechanisms. This paper presents a novel approach to improve VANET security by combining the Vehicular Delay-Tolerant Network (VDTN) protocol with the Deep Reinforcement Learning (DRL) technique known as the Twin Delayed Deep Deterministic Policy Gradient (TD3) algorithm. A store-carry-forward method is used by the VDTN protocol to resolve the problems caused by inconsistent connectivity and disturbances in VANETs. The TD3 algorithm is employed for capturing and detecting Worm Hole Attack (WHA) behaviors in VANETs, thereby enhancing security measures. By combining these components, it is possible to create trustworthy and effective communication channels as well as successfully detect and stop rushing attacks inside the VANET. Extensive evaluations and simulations demonstrate the effectiveness of the proposed approach, enhancing both security and communication efficiency.

• Journal of Korean Society for Quality Management
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• v.51 no.4
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• pp.573-588
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• 2023

Purpose: This study presents a research approach that utilizes deep reinforcement learning to construct optimal portfolios based on the business cycle for stocks and other assets. The objective is to develop effective investment strategies that adapt to the varying returns of assets in accordance with the business cycle. Methods: In this study, a diverse set of time series data, including stocks, is collected and utilized to train a deep reinforcement learning model. The proposed approach optimizes asset allocation based on the business cycle, particularly by gathering data for different states such as prosperity, recession, depression, and recovery and constructing portfolios optimized for each phase. Results: Experimental results confirm the effectiveness of the proposed deep reinforcement learning-based approach in constructing optimal portfolios tailored to the business cycle. The utility of optimizing portfolio investment strategies for each phase of the business cycle is demonstrated. Conclusion: This paper contributes to the construction of optimal portfolios based on the business cycle using a deep reinforcement learning approach, providing investors with effective investment strategies that simultaneously seek stability and profitability. As a result, investors can adopt stable and profitable investment strategies that adapt to business cycle volatility.

• Journal of Radiation Protection and Research
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• v.35 no.4
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• pp.172-177
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• 2010

The radioactive effluents from pressurized heavy water reactors (PHWRs) are relatively larger than those from pressurized water reactors (PWRs). Futhermore, radioactive effluents from PHWRs are released continuously. Thus, the discharge of radioactive effluents is strictly controlled. To do this, radiation detectors are installed at stacks of reactor buildings to monitor the concentration of radioactive effluents in real-time. Derived release limits (DRLs) of annual discharge are also set up for each radionuclide and effluents are rigidly controlled not to exceed those limits. In this paper, the discharge process of radioactive effluents, the standard for establishment of DRL and its methodology, and currents status for PHWRs were reviewed.

• Journal of Korean Tunnelling and Underground Space Association
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• v.13 no.3
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• pp.243-260
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• 2011

To predict TBM performance in design stage is indispensable for its successful application. The NTNU model, one of the representative TBM performance prediction models uses two distinct parameters such as DRI and CLI obtained from three different tests on bored rock cores. Based on DRI and CLI, it is possible to predict TBM advance rate and cutter life in the NTNU model. In this study, NTNU testing methods and their related testing equipments were introduced to measure DRl and CLI for the NTNU model. Then, in order to derive their relationships, the two key parameters measured for 39 domestic rocks were compared with physico-mechanical properties of rock such as uniaxial compressive strength and quartz content. Lastly, the experimental results were also compared with NTNU database to verify their reliability.

• Korean Journal of Veterinary Research
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• v.40 no.1
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• pp.101-109
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• 2000

Duck viral hepatitis is an acute, highly infectious viral disease of young dacklings aged from two days to three weeks. The significant lesion associated with the disease was enlarged liver including necrotic foci and numerous hemorrhagic spots. We have isolated five strains of duck hepatitis virus (DHV) from field cases showing about 20% mortality with a sign of opisthotonos. When a-day-old ducklings were intramuscularly inoculated with one of the isolates, 92% of the birds were died within 5 days. We attempted to develop an attenuated strain of duck hepatitis virus (DHV) using one of the isolates by serial chicken embryo passages. The propagation of DHV in chicken embryos was carried 140 passages. The virus titer increased gradually from the $21^{st}$ through the $50^{th}$ passage, but there was no significant increase of virus titer in subsequent passages after then. Through the serial passages, the virulence of the virus for chicken embryos was gradually increased but decreased for ducklings. The pathogenicity of the virus for ducklings was preserved up to the $21^{st}$ passage but disappeared at the $50^{th}$passage. An attenuated Korean isolate which was passaged 140 times in chicken embryos gave good protection in ducklings against both challenge infection to a Korean virulent strain and to a DHV-DRL strain, a type 1 reference strain of DHV, which indicated that the Korean isolates could be classified as DHV type 1. And the above results suggest that an attenuated Korean isolate can be used for developing a live DHV vaccine.

• Journal of radiological science and technology
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• v.44 no.5
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• pp.451-457
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• 2021

Recently, the number of interventional procedures has increased dramatically as an alternative of invasive surgical procedure and patient radiation exposure is also increasing accordingly. In this study, we evaluated the patient dose of major interventional procedures nationwide and we established our Korean database. With these results, we tried to suggest the reference dose level for major interventional procedures. We evaluated patent dose data in the field of interventional radiology from foreign countries. Measurement of radiation dose exposure for 11 major interventional procedures was conducted using embedded DAP meters in 10,006 patients from 47 hospitals, and reference level of each interventional procedure was suggested. The DRLs of each intervenional procedure are as follows: TACE 206(Gy·cm²), AVF 12(Gy·cm²), LE intervention 43(Gy·cm²), TFCA 122(Gy·cm²), Cerebral aneurysm coil embolization 214(Gy·cm²), PTBD 22(Gy·cm²), Biliary stent 60(Gy·cm²), PCN 7(Gy·cm²), Hickman catheter 2.1(Gy·cm²), Chemoport 1.4(Gy·cm²), BAE 104(Gy·cm²). Compared with the previously established DRL in 2012, the radiation dose decreased in all 10 interventional procedures. In the future, continuous publicity and education on the radiation dose reduction will be needed.