• Journal of the Korea Institute of Information and Communication Engineering
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• v.26 no.6
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• pp.881-889
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• 2022

As interest in environmental pollution caused by ship emissions is increasing worldwide, many studies are being conducted on the development of systems that increase energy efficiency to reduce ship emissions. In order to test the energy management system controller driven in real time on a large ship, it is necessary to perform the test through the simulator. In this study, addresses were set for each signal according to Modbus TCP/IP so that each control system and energy management system could be linked, and the algorithm was configured according to the signal flow. In addition, the signal generator was designed and manufactured so that each controller could artificially generate the signal collected from the vessel. As a result of the simulator production and interlocking, it was confirmed that each controller operated in real time performed its role appropriately, and that the algorithm of the ship energy management system was properly applied.

• Journal of Dental Rehabilitation and Applied Science
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• v.38 no.3
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• pp.162-170
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• 2022

In the case of patients with pathological tooth wear, it is necessary to evaluate the loss of the vertical dimension. Setting the appropriate vertical dimension is important to rehabilitate the patient's stable intermaxillary relationship. A 77-year-old female patient's chief complaint was the pain of the mandibular incisors and the lack of molars. At the first visit, pathologic tooth wear of the mandibular incisors were observed. After diagnosis and evaluation, loss of vertical dimension was not observed, but insufficient intermaxillary space for prosthetic restoration was confirmed. Mandibular rehabilitation was performed with vertical dimension increase and this showed satisfactory results both functionally and aesthetically.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2022.05a
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• pp.82-84
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• 2022

In recent years, research has been actively conducted to solve overhead problems caused by the increase in the number of IoT devices. MQTT, one of the IoT lightweight protocols for resolving performance degradation in IoT environments, is standardized to enable efficient operation in many-to-many communication environments, but there is a security vulnerability as it does not provide encryption by default. Although TLS communication technology can be applied to solve these problems, it is difficult to meet IoT's lightweight power-saving requirements. This paper introduces the latest MQTT communication encryption trends and analyzes IoT applicability by comparing TLS encryption and payload encryption methods.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2022.10a
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• pp.146-149
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• 2022

With internet development, many peoples use their email to exchange documents, register for web services, and much more. Some individuals/organizations (including educational institutions) use their own domain name for email instead of a domain provided by commercial email services. However, suppose the domain used for custom email expires. In that case, other individuals/organizations can reuse the domain, and the new domain owner can send and receive all emails incoming to the domain. It makes us concerned about Privacy violations. Email that new domain owners can look into also contains sensitive emails like password reset notifications, credit card statements, order history, and more. In this research, we would like to describe the privacy violations caused by the expired domain used for email that did not remove all dependencies of email users and propose a solution.

• Proceedings of the Korea Information Processing Society Conference
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• 2007.11a
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• pp.1014-1017
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• 2007

무선랜에서는 작은 셀 크기로 인해 노드들의 이동에 따른 빈번한 핸드오프가 이루어진다. 그래서 무선랜에서는 지속적인 통신 서비스를 제공하기 위한 방법으로 모바일 아이피와 같은 방법을 개발하고 있다. 모바일 아이피는 모바일 노드가 한 장소에서 다른 장소로 이동할 때 IP 주소의 변경 없이도 이동할 수 있도록 해준다. 그러나 모바일 아이피는 긴 시간의 등록과정과 연결 재설정 때문에 시간지연이나 패킷 손실과 같은 오버헤드를 발생시킨다. 따라서 무선랜의 QOS(Quality Of Service)를 향상시키기 위해서 Mobile IP 의 핸드오프 시간을 줄여야만 한다. 본 논문은 이러한 문제를 해결하기 위해 핸드오프 지연 시간을 감소시키는 기법을 제안한다. 제안기법의 기본 아이디어는 모바일 노드의 이동 네트워크를 예상하여, 미리 패킷 포워딩을 수행하는데 있다. 우리는 각 모바일 노드들에게 connection proxy table 정보를 추가하였다. 그리고 이 테이블 정보를 이용함으로써 모바일 노드들은 홈에이전트와 포린에이전트에 COA(Care of address)를 미리 등록하는 것이 가능해졌다. 그 결과로 이동 노드들은 홈 네트워크를 완전히 벗어나지 않고도 핸드오프가 이루어져 지속적인 서비스가 가능하였다. 본 논문에서 제안하는 기법이 기존 Mobile IP 와 비교해 볼 때 핸드오프가 이루어지는 동안 비 연결 시간을 줄일 수 있다는 것을 실험결과를 통해서 확인할 수 있었다.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.47 no.1
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• pp.58-68
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• 2010

In this paper, we propose an efficient link protection switching scheme for provider backbone bridge systems with a spanning tree for backup links exclusively, and evaluate its performance. The proposed scheme offers guaranteed QoS flows even when a link fault occurrs in the primary link by flooding the flows over the profiled spanning tree. The flooding mechanism over the spanning tree can also provide low latency and remove the loopback flows. We also derive the efficiency of bandwidth usage for the normal flows and the number of lost frames during the link restoration. For evaluating its feasibility, we implement a prototype of PBB-TE systems based on the Linux bridge codes, which can support both link protection switching capability with CCM and MAC-in-MAC encapsulation. A related protocol analyzer is also developed. One can see that the proposed scheme and the prototype can be useful for developing carrier class Ethernet systems based on PBB-TE.

• Journal of the Korea Society of Computer and Information
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• v.25 no.11
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• pp.277-286
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• 2020

In this paper, we propose a new educational approach to help learners form concepts by identifying the properties of programming concepts targeting a group of experts in programming education. Therefore, we confirmed the typical properties of concepts by programming education experts for programming learning elements through conceptual metaphor analysis, which is a qualitative research method, and confirmed the validity through the delphi method. As a result of this study, we identified 17 typical properties of programming concepts that learners should form in programming education. The conclusions of this study are that need to compose the educational content more specifically for the conceptualization of learners' programming as follows: 1)the concept of a variable is to understand how to store data, how to set a name, what an address has, how to change a value, various types of variables, and the meaning of the size of a variable, 2)the concept of operator is to understand how to operate the four rules, how to deal with it logically, how to connect according to priority, meaning of operation symbols, and how to compare, 3)the concept of the control structure is to understand how to control the execution flow, how to make a logical judgment, how to set an execution rule, meaning of sequential execution, and how to repeat executing.

• Journal of the Institute of Convergence Signal Processing
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• v.12 no.4
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• pp.274-280
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• 2011

Due to their rapid growth and new paradigm applications, wireless sensor networks(WSNs) are morphing into low power personal area networks(LoWPANs), which are envisioned to grow radically. The fragmentation and reassembly of IP data packet is one of the most important function in the 6LoWPAN based communication between Internet and wireless sensor network. However, since the 6LoWPAN data unit size is 102 byte for IPv6 MTU size is 1200 byte, it increases the number of fragmentation and reassembly. In order to reduce the number of fragmentation and reassembly, this paper presents a new scheme that can be applicable to 6LoWPAN. When a fragmented packet header is constructed, we can have more space for data. This is because we use 8-bits routing table ill instead of 16-bits or 54-bits MAC address to decide the destination node. Analysis shows that our design has roughly 7% or 22% less transmission number of fragmented packets, depending on MAC address size(16-bits or 54-bits), compared with the previously proposed scheme in RFC4944. The reduced fragmented packet transmission means a low power consumption since the packet transmission is the very high power function in wireless sensor networks. Therefore the presented fragmented transmission scheme is well suited for low-power wireless sensor networks.

• Journal of the korean academy of Pediatric Dentistry
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• v.34 no.2
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• pp.292-298
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• 2007

In order to thoroughly understand change patterns and to set up an appropriate approach the direction of future treatment towards children in Chonbuk area, we carried out this research. we could draw below conclusions from the studies based on researches of distribution of new patients visited Dept. of Pediatric Dentistry, Chonbuk Nat' university from 1998 to 2005 and current changes in dental treatment. 1. There was an increase in the number of patients until 2004 but it decreased in 2005. Boys took higher portion. 2. Number of patients increased during school holidays. 3. 97.7% of patients were urbanites. 4. An age group from 31 months to 6 years showing 48.2% was the highest, each percentage of $7{\sim}13$ years, $13{\sim}30$ months showed 31.3%, 17.2%. 5. 33.8% of patients were referred from local dental clinics and among them, an age group from 31 months to 6 years showing 49.5% was the highest, each percentage of $7{\sim}13$ years, $13{\sim}30$ months showed 35.2%, 12.9%. 6, 5.5% of patients who had systemic diseases, among them, each percentage of cardiovascular disease, mental retardation, respiratory disease showed 21.8%, 13.6%, and 11.0%. 7. According to the distribution of chief complaints, dental caries showing 42.9% was the highest. 8. Root canal treatment, restoration, prosthesis showing 42.6% were the highest of all treatments.

• Clinical and Experimental Pediatrics
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• v.45 no.8
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• pp.967-972
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• 2002

Purpose : A retrospective study was undertaken to evaluate the usefulness of low risk criteria for identifying febrile infants younger than three months unlikely to have serious bacterial infection. Methods : We conducted a retrospective study of 527 infants younger than three month with a axillary temperature ${\geq}37.4^{\circ}C$. If they met the following all four criteria, appear well, WBC $5,000-20,000/mm^3$, urine stick WBC(-) and nitrite(-), CSF WBC < $10/mm^3$, they were considered at low risk for serious bacterial infection(SBI). SBI was defined as a positive culture of urine, blood, or cerebrospinal fluid. The sensitivity, specificity, negative predictive value and positive predictive value of the low risk criteria were calculated. Results : Of 527 febrile infants, 110(21.0%) had serious bacterial infections. The 2.7% who met the low risk criteria had SBI and negative predictive value was 97.3%. SBI was diagnosed in 103 infants(38.6%) who didn't meet the low risk criteria including urinary tract infection(78.6%), most commonly, bacteremia(16.5%), bacterial meningitis(8.7%), Salmonella gastroenteritis(1%), osteomyelitis( 1%), septic arthritis of hip joint(1%). There were no differences in the sensitivity and negative predictive value according to the monthly-age-group. Conclusion : This low risk criteria to identify infants unlikely to have SBI early is available, however low risk infants must be carefully observed.