• KSII Transactions on Internet and Information Systems (TIIS)
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• v.14 no.11
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• pp.4268-4289
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• 2020

Advanced traffic signal timing method plays very important role in reducing road congestion and air pollution. Reinforcement learning is considered as superior approach to build traffic light timing scheme by many recent studies. It fulfills real adaptive control by the means of taking real-time traffic information as state, and adjusting traffic light scheme as action. However, existing works behave inefficient in complex intersections and they are lack of feasibility because most of them adopt traffic light scheme whose phase sequence is flexible. To address these issues, a novel adaptive traffic signal timing scheme is proposed. It's based on actor-critic reinforcement learning algorithm, and advanced techniques proximal policy optimization and generalized advantage estimation are integrated. In particular, a new kind of reward function and a simplified form of state representation are carefully defined, and they facilitate to improve the learning efficiency and reduce the computational complexity, respectively. Meanwhile, a fixed phase sequence signal scheme is derived, and constraint on the variations of successive phase durations is introduced, which enhances its feasibility and robustness in field applications. The proposed scheme is verified through field-data-based experiments in both medium and high traffic density scenarios. Simulation results exhibit remarkable improvement in traffic performance as well as the learning efficiency comparing with the existing reinforcement learning-based methods such as 3DQN and DDQN.

• Journal of the Society of Naval Architects of Korea
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• v.60 no.1
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• pp.57-64
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• 2023

Recently, the increased use of anti-ship guided missiles, a weapon system that detects and attacks targets in naval engagement, has come to pose a major threat to the survivability of ships. In order to improve the survivability of ships in response to such anti-ship guided missiles, many studies of means to counteract them have been conducted in militarily advanced countries. The integrated survivability of a ship can be largely divided into susceptibility, vulnerability, and recoverability, and is expressed as the conditional probability, if the ship is hit, of damage and recovery. However, as research on susceptibility is a major military secret of each country, access to it is very limited and there are few publicly available data. Therefore, in this study, a possibility of estimating the susceptibility of ships using an anti-air defense system corresponding to anti-ship guided missiles was reviewed. To this, scenarios during engagement, weapon systems mounted to counter threats, and maximum detection/battle range according to the operational situation of the defense weapon system were defined. In addition, the effectiveness of the anti-air defense system and susceptibility was calculated based on the performance of the weapon system, the crew's ability to operate the weapon system, and the detection probability of the detection/defense system. To evaluate the susceptibility estimation feasibility, the sensitivity of the detailed variables was reviewed, and the usefulness of the established process was confirmed through sensitivity analysis.

• Current Photovoltaic Research
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• v.11 no.4
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• pp.134-143
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• 2023

Efforts are being made to respond to global warming. Interest in and demand for the private sector-led RE100 campaign is also increasing. Self-built solar power generation, one of the implementation tools for RE100, is not expanding. However, it can be an economical means of implementation in the long run. In this study, we intend to analyze the impact on the optimal ratio of self-solar power generation using HOMER simulation. OPR defines the optimal solar power generation ratio and looks into what changes there are in the optimal solar power ratio when self-power consumption increases and external power purchase price changes. As a result, the optimal rate of self-solar power generation has a low impact even if self-power consumption increases. As the external power unit price increases, the optimal ratio increases, and at a power unit price of 100 KRW/kWh, OPR is 24%; at 200 KRW/kWh OPR is 31%; and at 300 KRW/kWh OPR is 34%. This shows that the electricity price replaced during the life cycle has a high impact on the economic feasibility of solar power generation. However, when the external power unit price reached a certain level, the increase in OPR decreased. This shows that it is difficult for domestic companies to achieve RE100 based on the economic feasibility of solar energy alone. Therefore, efforts are needed to supply renewable energy in the public sector.

• (The)Korea Educational Review
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• v.23 no.4
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• pp.101-133
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• 2017

This Study aims to evaluate teacher policy in the Park Administration and to suggest tasks based on the results. To attain the aim, it describes overall teacher policy process in Park Administration and evaluates teacher policy based on the criteria which was driven from the CIPP model. The conclusions are summarized as follows. First, the environmental suitability of the situation assessment was met in general. The reason for this was that the teacher policy of the Park Geun-hye government was introduced reflecting changes in the environment and demands of policy stakeholders. The validity and feasibility of the policy objective of the input evaluation were not satisfied. There were deficiencies in the objectives of the policy measures. The objectives of the measures were not linked to the policy objectives. The budget necessary for policy enforcement were not secured. In future policy design, efforts should be made to examine whether the policy goals are valid, to secure resources necessary for policy implementation and to increase the feasibility of policies. The procedural rationality of the process evaluation and the suitability of the means were not met. Discussion with the interest group was omitted, it was not clear whether the implementation of the policy was linked to the policy goal. In the future, it will be necessary to focus on procedures such as communication and collaboration with stakeholders, to make immediate revisions in case of problems. The effectiveness and satisfaction of the output evaluation were low. Because the validity of the policy objectives, the suitability of the means, and procedural rationality were not satisfied. In the future, it will be necessary to systematically design policies and communicate with stakeholders in the execution process to prevent policy failures and actively.

• Journal of the Korean Society of Radiology
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• v.17 no.5
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• pp.679-684
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• 2023

Venous puncture is widely used to obtain blood samples for pathological examination. Because the invasive venipuncture method using a needle is repeatedly performed, the pain suffered by the patient increases, so our research team pre-developed a miniaturized near-infrared (NIR) imaging system in advance. To improve the image quality of the acquired NIR images, this study aims to model the non-local means (NLM) algorithm, which is well known to be efficient in noise reduction, and analyze its applicability in the system. The developed NIR imaging system is based on the principle that infrared rays pass through dichroic and long-pass filters and are detected by a CMOS sensor module. The proposed NLM algorithm is modeled based on the principle of replacing the pixel from which noise is to be removed with a value that reflects the distances between surrounding pixels. After acquiring an NIR image with a central wavelength of 850 nm, the NLM algorithm was applied to segment the final vein area through histogram equalization. As a result, the coefficient of variation of the NIR image of the vein using the NLM algorithm was 0.247 on average, which was an excellent result compared to conventional filtering methods. In addition, the dice similarity coefficient value of the NLM algorithm was improved by 62.91 and 9.40%, respectively, compared to the median filter and total variation methods. In conclusion, we demonstrated that the NLM algorithm can acquire accurate segmentation of veins acquired with a NIR imaging system.

• Journal of Korea Water Resources Association
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• v.31 no.5
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• pp.621-635
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• 1998

The feasibility of cloud seeding in Korea is presented from analyses of precipitation, cloud amount, satellite data, and upper air data. The daily mean precipitation over Dae-Kwan-Ryong is the largest(~4.5 mm/day), while the intensity of precipitation (amount of yearly rainfall divided by the frequency of rain days) over Southern area is above 14 mm/day, which shows the largest in Korea. Both the daily mean and the intensity of precipitation over Andong area are the smallest with values of ~2.7 mm/day and ~11 mm/day, respectively. In the meanwhile, the occurrence frequency of appropriate cloud top temperature (-10'~-30') for cloud seeding over the region has a large value (~130 days/year). The precipitation patterns of the region vary with wind direction and intensity calculated from 43 AWSs(Automatic Weather Station) and the additional 7 rain guages which were installed along Northern and Southern part of the Sobaek mountain. The Sc(Stratocumulus) cloud type over Andong is frequently observed, and Cirrus and Altostratus next. From the results, it is estimated that the feasibility of cloud seeding over the area would be high if a proper strategy of cloud seeding is set up. LCL (Lifting Condensation Level) and CCL (Convective Condensation Level) have the most frequency in 1000-950 hPa being occupied 4/9 of total analysis period and in 400-500 hPa, respectively, with both small variations from season to season. The correlation between vapor mixing ratio and CCL is the highest in Summer and the lowest in Winter. It means that the height of cumulus in Summer is high with an abundant water vapor but vice versa in Winter, and that the strategy of cloud seeding should be different with seasons.

• Korean Journal of Agricultural and Forest Meteorology
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• v.25 no.3
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• pp.236-244
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• 2023

The purpose of this study was to examine the economic feasibility of providing services according to the nationwide expansion of early warning services. The net present value method, one of the cost-benefit analysis methods, was applied to the analysis. As a benefit item that constituted the net present value, the damage reduction amount using crop insurance data and the willingness to pay for the use of early warning services were used. The cost items included system construction and maintenance costs, and text transmission costs. As a result of the analysis, it was found that the nationwide expansion of early warning services had economic feasibility, and its economic effect varied depending on the level of text message use (10 % to 40 %, 10 %p interval) of participating farmers. In the future, the economic effect of early warning services is expected to increase further due to the increase in the number of farmers participating in early warning services and the increase in crop damage caused by climate change. It is necessary to further enhance the economic effect of early warning services by actively utilizing information delivery means through apps or the web as well as text messages.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.39C no.2
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• pp.199-208
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• 2014

Code division multiple access (CDMA) is one of the promising medium access control (MAC) schemes for underwater acoustic sensor networks because of its robustness against frequency-selective fading and high frequency-reuse efficiency. As a way of performance evaluation, sea or lake experiment has been employed along with computer simulation.. In this study, we design the underwater CDMA forward-link transceiver and evaluate the feasibility aginst harsh underwater acoustic channel in water-tank first. Then, based on the water-tank experiment results, we improved the transceiver and showed the improvements in a lake experiment. A pseudo random noise code acquisition process is added for phase error correction before decoding the user data by means of a Walsh code in the receiver. Interleaving and convolutional channel coding scheme are also used for performance improvement. Experimental results show that the multiplexed data is recovered by means of demultiplexing at receivers with error-free in case of two users while with less than 15% bit error rate in case of three and four users.

• Journal of Information Technology and Architecture
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• v.11 no.1
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• pp.11-23
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• 2014

Kill Chain is getting attention due to North Korea's recent nuclear test and missile launches and has emerged the need for an early build up. In order to build a materialized kill chain, you should review the unique kill chain to support operations effectively using various sensors and striking weapon system. Especially, you need a suitable network to reduce a reaction time against the enemy attack under joint operations environment etc. Currently there are many communication ways(e.g. data link, voice, video and text message) used in operations through satellite, wired and wireless and so on. Now, this paper contains analysis on various means for target information exchange which are used in the kill chain. And appropriate network of the kill chain for target information transmission is addressed to confirm feasibility of its alternatives, which is developed using AHP(Analytic Hierarchy Process). Finally, this paper is suggesting network and means of its building up for target information transmission of kill chain which can be implemented under the situation of joint battle field.

• The Journal of Korean Obstetrics and Gynecology
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• v.31 no.2
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• pp.31-48
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• 2018

Objectives: This study was performed to observe the correlations between the results of ABR-2000 and DSOM / 3D-MAC to evaluate the feasibility of ABR-2000 as a oriental medical diagnostic criteria. Methods: We studied 547 women visiting ${\bigcirc}{\bigcirc}$ hospital from December 2012 to June 2015. The subjects were categorized in two groups, 'Hypotonia' and 'Non-Hypotonia' by the result of ABR-2000 and assessed the result of DSOM, 3D-MAC for each group. The differences of pulse wave factors by group also studied. Results: 1. There was no significant difference between two groups about the output frequency of pathogenic factors in DSOM while the result showed the higher correlation in Hypotonia group in terms of the companion tendency of pathogenic factors and syndromes formed by the combination of pathogenic factors. 2. The pulse waves of Hypotonia group were mostly slow, weak, tense and stiff than Non-Hypotonia group. Conclusions: 1. In Hypotonia group, yin deficiency (陰虛) factor was frequently accompanied and consumption (虛損) of various organs based on the yin deficiency (陰虛) was observed. It means chronic and severe condition of exhaustion syndrome (虛勞). 2. The result of 3D-MAC also means pathological feature of yin syndrome (陰 證) and consumption (虛損). Besides, lower scores of Body Surface Area (BSA), body weight, and Body Mass Index (BMI) were associated with body weakness (體瘦), a symptom of exhaustion syndrome (虛勞).