• KSII Transactions on Internet and Information Systems (TIIS)
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• v.13 no.11
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• pp.5335-5353
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• 2019

The definition of the bandwidth efficiency (BE) of cognitive cooperative network (CCN) is the ratio between a number of the licensed slot(s) or sub-channel(s) used by the unlicensed users to transmit a single data packet from the unlicensed transmitter to unlicensed destination, and from unlicensed relay(s) to unlicensed destination. This paper analyzes and improves the BE in the underlay CCN with a new reactive relay selection under interference and power constraints. In other words, this paper studies how unlicensed cooperative users use the licensed network slot(s) or sub-channel(s) efficiently. To this end, a reactive relay selection method named as Relay Automatic Repeat Request (RARQ) is proposed and utilized with a CCN under interference and power constraints. It is shown that the BE of CCN is higher than that of cooperative transmission (CT) due to the interference and power constraint. Furthermore, the BE of CCN is affected by the distance of the interference links which are between the unlicensed transmitter to the licensed destination and unlicensed relay to the licensed destination. In addition, the BE for multiple relays selection over a CCN under interference and power constraints is also analyzed and studied, and it is shown that the BE of CCN decreases as the number of relays increases.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.15 no.7
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• pp.2668-2717
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• 2021

Demands for high-speed wireless data services grow rapidly. It is a big challenge to increasing the network capacity operating on licensed spectrum resources. Unlicensed spectrum cellular networks have been proposed as a solution in response to severe spectrum shortage. Licensed Assisted Access (LAA) was standardized by 3GPP, aiming to deliver data services through unlicensed 5 GHz spectrum. Furthermore, the 3GPP proposed 5G New Radio-Unlicensed (NR-U) study item. On the other hand, artificial intelligence (AI) has attracted enormous attention to implement 5G and beyond systems, which is known as Intelligent Radio (IR). To tackle the challenges of unlicensed spectrum networks in 4G/5G/B5G systems, a lot of works have been done, focusing on using Machine Learning (ML) to support resource allocation in LTE-LAA/NR-U and Wi-Fi coexistence environments. Generally speaking, ML techniques are used in IR based on statistical models established for solving specific optimization problems. In this paper, we aim to conduct a comprehensive survey on the recent research efforts related to unlicensed cellular networks and IR technologies, which work jointly to implement 5G and beyond wireless networks. Furthermore, we introduce a positioning assisted LTE-LAA system based on the difference in received signal strength (DRSS) to allocate resources among UEs. We will also discuss some open issues and challenges for future research on the IR applications in unlicensed cellular networks.

• Journal of the Korean Academy of Child and Adolescent Psychiatry
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• v.22 no.2
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• pp.67-73
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• 2011

The purpose of licensing system is to ensure that the medicines are examined for safety, efficacy and quality. Nevertheless, off-label or unlicensed drug usages in pediatric practice is widespread in Korea and worldwide. Psychotropics are one of the most commonly used off-label or unlicensed drugs. The most valid approach to face this dilemma will be to have more evidences from pediatric pharmacological studies. Clinicians, in addition, need to monitor closely their off-label or unlicensed drug prescriptions to minimize the trial and error in practice. Researchers should publish their experiences and provide guidelines. Pharmaceutical companies, regulatory authorities, and consumer organizations should endeavor altogether for the children's right to get safe and efficacious drugs as adults do. Here, the definition as well as the current status of off-label and unlicensed drug prescriptions will be introduced. Critical issues regarding the off label drugs are discussed. In addition, I will describe the present condition as to the off-label and unlicensed drugs in child and adolescent psychiatry and the authorization process of off-label drug prescription in Korea. Lastly, direction we should like to take in this field will be mentioned.

• The Korean Society of Law and Medicine
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• v.11 no.1
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• pp.243-270
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• 2010

Under the existing law, an act included in medical practice by medical personnel seems to be irrelevant to whether the act concerned in the "Life World" is in the category of medical practice. In spite of the act having been done according to the custom for a long time, and generally done by individuals in the "Life World", these kinds of acts have been banned by law, because if these acts were done by the general individuals, it would be considered as harmful behavior to human life and body. And it is not sure that individuals know such a ban or notification. This cause a "Mistake of Law". Also it is happened if someone knows the existence of law but believes that his/her act is not included. For treating the problem of "Mistake of Law" of unlicensed medical act, in this study I inquired thoroughly into the category and regulation of unlicensed medical act, uncertainty of the Medical Services Law the first Section of Article 27, the prohibition of unlicensed medical act. The "Composition Condition" of the first Section of Article 27 of the Medical Services Law is not certain, it doesn't meet the "Doctrine of Clearance", and it cause the "Mistake of Law". Also it doesn't meet standardization of constitutional state. An exceptional decision of Pusan District Court, the debate about unlicensed medical practice, constitutional decision on unlicensed medical practice of the Constitutional Court of Republic of Korea and point of view of support of regulation. Also I examined the problem of "Mistake of Law" that the regulation of unlicensed medical practice has. I tried to solve uncertainty of "Composition Condition" and proposed a direction of regulation for solving the "Mistake of Law" and the use of existing law.

• The Korean Society of Law and Medicine
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• v.11 no.2
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• pp.11-74
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• 2010

This article analyzes legal meaning and definition of medical practice examining Korean Supreme Court cases. Until now, there is no right answer about the meaning of medical practice and it is also hard to define of it. Moreover, not only Acts and regulations containing medical practice but also many cases ruling a person who practice medicine, the concept of medical practice involves various meanings. So, it has caused confusion. In order to solve this problem, this article divides the medical practice's meaning into range and nature within prohibition article of the Medical Act about unlicensed personnel who practice medicine. After providing a explanation of the meaning of medical practice according to amendment of the Act, this article disputes the meanings of the several cases following the amendment. And then analyzing non-medical person's unlicensed medical practice and medical person's unlicensed medical practice. In order to provide more accurate legal concept of medical practice when Korean government amends the Medical Act or making policies in this field, this classifying analysis approach should be needed. Looking at the result, in general, Korean Supreme Court has interpreted unlicensed prohibition clause of the Medical Act widely; not only non-medical person's unlicensed medical practice but also medical person's unlicensed medical practice. Therefore, this article suggests that the prohibition clause needs to be careful applying to non-medical practice. Because, in fact, even though there are some necessity of non-medical practice, there are no qualificatory or license system of non-medical practitioner in the Medical Acts or regulations forbidding whole non-medical practices. Furthermore, the Supreme Court has decided medical person's unlicensed medical practice too narrowly, thus it does not keep up with rapid change of medical development and people's demands these days. Regarding this subject, in order to take advantage of medical practitioners effectively and cope with increasing people's medical demands, this article proposes that medical person's unlicensed medical practice only to be prohibited in case of endangering our public health.

• Journal of Advanced Navigation Technology
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• v.24 no.5
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• pp.415-422
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• 2020

Federal Communications Commissions (FCC) has adopted a new rule that can provide a 1,200 MHz unlicensed spectrum to maximize the public benefits in the 5.925 ~ 7.125 GHz(6 GHz) band by expanding unlicensed broadband into the 6 GHz band while also ensuring that licensed services that operate in the band continue to thrive. In Korea, the M/W band of 6 GHz has been reallocated to introduce unlicensed services in the 6 GHz band. Considering the national interests, the entire 1,200 MHz will be supplied for the indoor uses, but only the 500 MHz of the lower bandwidth (5925 ~ 6425 MHz) will for the outdoor uses under the limited power to protect the incumbent services. The introduction of unlicensed devices is being actively promoted through the reallocation of the 6 GHz M/W band, but since it is desperately necessary to prepare technical requirements to operate them in Korea. In this paper, the US 6 GHz unlicensed rules has been analyzed, these results will be utilized for establishing Korean technical standards with the unlicensed spectrum expansion.

• Journal of Communications and Networks
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• v.17 no.4
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• pp.362-369
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• 2015

This study addresses the effects of channel estimation error and mutual interference between licensed and unlicensed systems on outage performance of reactive relay selection in unlicensed systems over independent non-identical (i.n.i) Rayleigh fading channels and under both the maximum transmit power constraint and primary outage constraint. Toward this end, power allocation for unlicensed users is first recommended to satisfy both constraints and account for channel estimation error and mutual interference. Then, we derive an exact closed-form outage probability representation for unlicensed systems to quickly evaluate this effect in key operation parameters. Various results corroborate the derived expressions and provide useful insights into system performance.

• Journal of Distribution Science
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• v.15 no.8
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• pp.29-36
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• 2017

Purpose - This paper proposes some ideas with a view to reducing any possible accidents caused by unlicensed drivers and an illegal use of other's name, particularly by teenagers in consideration of easy and simple instruction on smartphone with very weak and mere consciousness on auto life. Research design, data, and methodology - This study analyzes some accident cases between cargo trucks and rental cars in South Korea, and unlicensed vehicle with unlicensed drivers who use rental cars collided with cargo trucks which were loaded a lot of goods to be delivered to buyer designated. In order to fulfill this research, a case study accompanied with literature survey was conducted. Ideal suggestion for the right growth on rental car industry will be realized by legislation of the law. Results - This paper classified bodily injury of the victim, property damage and damaged cargo arising out of the unlicensed who is driving on car sharing service in South Korea. Conclusions - For the purpose of reducing cargo accidents caused by unlicensed drivers and an illegal use of other's name particularly by teenagers, this paper proposes some ideas of Amendment of the law, Paradigm shift of car sharing company, Preparation by association side and Technical Complementary Measures in South Korea.

• KIPS Transactions on Computer and Communication Systems
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• v.12 no.10
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• pp.299-308
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• 2023

As the spectrum shortage problem has accelerated by the emergence of various services, New Radio-Unlicensed (NR-U) has appeared, allowing users who communicated in licensed bands to communicate in unlicensed bands. However, NR-U network users reduce the performance of Wi-Fi network users who communicate in the same unlicensed band. In this paper, we aim to simultaneously maximize the fairness and throughput of the unlicensed band, where the NR-U network users and the WiFi network users coexist. First, we propose an optimal power allocation scheme based on Monte Carlo Policy Gradient of reinforcement learning to maximize the sum of rates of NR-U networks utilizing rate-splitting multiple access in unlicensed bands. Then, we propose a channel occupancy time division algorithm based on sequential Raiffa bargaining solution of game theory that can simultaneously maximize system throughput and fairness for the coexistence of NR-U and WiFi networks in the same unlicensed band. Simulation results show that the rate splitting multiple access shows better performance than the conventional multiple access technology by comparing the sum-rate when the result value is finally converged under the same transmission power. In addition, we compare the data transfer amount and fairness of NR-U network users, WiFi network users, and total system, and prove that the channel occupancy time division algorithm based on sequential Raiffa bargaining solution of this paper satisfies throughput and fairness at the same time than other algorithms.

• 한국정보통신설비학회:학술대회논문집
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• 2007.08a
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• pp.354-358
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• 2007

This article presents several methods of mobile communication network to access technologies utilizing unlicensed spectrum interworking. Generic Access Network (GAN) technology was already specified in GERAN (GSM EDGE Radio Access Network) and Interworking WLAN (I-WLAN) was standardized for WCDMA system for WLAN user to access WCDMA packet based services through WLAN access point. Voice Call Continuity is not access network dependent technology but is a kind of domain change scheme for voice call from Circuit Switching (CS) network to IP Multimedia Subsystem (IMS) and vice versa.