• 한국통신학회논문지
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• 제29권8C호
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• pp.1086-1103
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• 2004

Most research efforts on the OCDMA technology assume single-bit-per-symbol transmission techniques such as on-off keying. However, achieving high spectral efficiency with such transmission techniques is likely to be a challenging task due to the "unipolar" nature of optical signals. In this paper, an M-ary transmission technique using more than two equally-weighted codes is proposed for OCDMA local area networks, and ie BER performance and spectral efficiency are analyzed. Poison frame arrival and randomly generated codes are assumed for the BER analysis, and the probability of incorrect symbol detection is analytically derived. From the approximation, it is found that there exists an optimal code weight that minimizes the BER, and its physical interpretation is drawn in an intuitive and simple statement. Under the assumption of this optimized code weight and sufficiently large code dimension, it is also shown that the spectral efficiency of OCDMA networks can be significantly improved by increasing the number (M) of symbols used. Since the cost of OCDMA transceivers is expected to increase with the code dimension, we finally provide a guideline to determine the optimal number of symbols for a given code dimension and traffic load.

• 한국인쇄학회지
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• 제22권2호
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• pp.199-211
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• 2004

The drying speed of gravure ink are very fast because of evaporation drying type. The gravure ink are fitly selected variety resin and solvent for a wide range printing are adopted. Moreover, after-manufacture handling is necessary to various purposes. Though composition of gravure ink are same those of another printing ink, the viscosity of it are vary low compare with another printing inks. As property of variety printed matters, improvement of performance of printing layer and suitable after-manufacture handling, the more research of gravure ink are to be continue for development of printing technology. Generally, the gravure ink are made up resin, pigment, solvent and additive. Especially solvent are fitly selected for solution of resin, viscosity, and drying speed. Furthermore, it tis care of bad smell of remaining resin, poison and danger of fire of it. Because of the prevention of air pollution as restriction deflation of solvent, custody of dangerous object and improvement of work environment as labor safety hygiene and fire-low, the environment restriction of printing business become strict. This study has purpose of development of gravure ink of involved 30% below of alcohol is used for PVC film printing.

• 한국경영과학회:학술대회논문집
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• 대한산업공학회/한국경영과학회 1995년도 춘계공동학술대회논문집; 전남대학교; 28-29 Apr. 1995
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• pp.729-738
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• 1995

We consider a priority-based packet-switching system with three phases of the packet transmission time. Each packet belongs to one of several priority classes, and the packets of each class arrive at a switch in a Poison process. The switch transmits queued packets on a priority basis with three phases of preemption mechanism. Namely, the transmission time of each packet consists of a preemptive-repeat part for the header, a preemptive-resume part for the information field, and a nonpreemptive part for the trailer. By an exact analysis of the associated queueing model, we obtain the Laplace-Stieltjes transform of the distribution function for the delay, i.e., the time from arrival to transmission completion, of a packet for each class. We derive a set of equations that calculates the mean response time for each class recursively. Based on this result, we plot the numerical values of the mean response times for several parameter settings. The probability generating function and the mean for the number of packets of each class present in the system at an arbitrary time are also given.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제13권6호
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• pp.3238-3257
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• 2019

Closed-circuit television (CCTV) technology continuously captures and stores video streams. Users are typically required by policy to store all the captured video for a certain period. Accordingly, increasing the number of CCTV operation cycles and photographing positions expands the amount of data to be stored. However, expanding the available storage space for video data incurs increased costs. In recent years, this problem has been addressed with cloud storage solutions, which enable multiple users and devices to access and store data simultaneously. However, because of the large amount of data to be stored, a vast storage space is required. Consequently, cloud storage administrators need a way to store data more efficiently. To save storage space, deduplication technology has been proposed to prevent duplicate storage of the same data. However, because cloud storage is hosted on remote servers, data encryption technology must be applied to address data exposure issues. Although deduplication techniques for encrypted data have been studied, there have been various security vulnerabilities. We attempted to solve this problem by addressing various issues such as poison attacks, property forgery, and ownership management while removing the redundant data and handling the data more securely.

• 정보보호학회논문지
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• 제25권1호
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• pp.83-94
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• 2015

중복 제거 기술(Deduplication)은 동일한 데이터에 대하여 중복 저장을 방지하는 기법으로 클라이언트(Client)와 클라우드 서버(Cloud Server) 간에 데이터를 저장하고 관리하는데 있어 효율성을 제공한다. 하지만 공개된 환경의 클라우드 서버에 데이터를 저장하고 관리하기 때문에, 클라이언트가 저장한 데이터에 대한 프라이버시 문제가 발생할 뿐만 아니라 데이터의 손실이 발생할 수도 있다. 최근 이러한 문제점들을 해결하기 위해 안전한 중복 제거 기술이 제안되었지만, 여전히 각각의 공격의 안전성에 대한 문제가 발생할 뿐만 아니라 비효율적이다. 본 논문에서는 2013년 Bellare 등이 제안한 기법의 키 서버(Key Server)와 질의-응답 메커니즘(Challenge-Response)을 이용하여 안전하고 효율적인 클라이언트 사이드 중복 제거 기술을 제안한다. 제안 기법은 클라이언트 사이드 중복 제거 기술에서 발생하는 다양한 공격에 대해 안전성을 제공하며, 크기가 큰 데이터를 업로드 하는 환경에서 높은 효율성을 제공한다.

• Clinical and Experimental Pediatrics
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• 제51권2호
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• pp.116-121
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• 2008

Unintentional injuries are the most important cause of morbidity and mortality in the pediatric population, and the home is the most common site of injury for children in Korea. The most common cause of injury was slip down. Fall down and burn were frequent in infant/toddlers group, automobile and bicycle accident more frequent in preschool children. Findings from the survey could then be used to provide targets for direct educational efforts by medical services and to direct environmental safety modifications tailored to the unique situation of each family. Pediatric toxic ingestions are treated commonly by pediatricians and emergency physicians. Significant injury after these ingestions is infrequent, but identifying the dangerous ingestion is sometimes a difficult task. By performing a detailed history, focused physical examination, and directed laboratory evaluation, an estimation of risk can be developed. According to recent Korean poison papers, there were bimodal peak of age distribution in poisoned children patient on the whole: infant and adolescents group. Various types of materials belonged the classes of drugs, household products, and industrial solvents. Most of the poisoned children patients had been poisoned accidentally, while most cases of adolescents poisoning had been intentional. More than half of the adolescents group had a suicidal purpose in Korea, so an understanding of the demographic factors associated with self-harm poisoning may provide useful information to improve prevention and treatment strategies.

• 한국농촌건축학회논문집
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• 제14권3호
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• pp.121-128
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• 2012

In recent years, the number of returnfarmer is increasing in Korea, interlinked with baby boomer's retirement. One of the returnfarmer's serious problems is the decision making for his returnfarm place. This study intends to get information about a ideal returnfarm place by interpreting Jung-Hwan Lee's written in the Choseon Dynasty, and to use it for returnfarmer's decision making as a lesson in the present age. In the results, this study could finds 8 evaluation criteria in his book except his 4 requirements for a ideal place to live : Ji-ri(地理, geographic), Saeng-ri(生理, physiology), In-sim(人心, popular mind), and San-su(山水, landscape), which are (1) distance from seoul, (2)multi-habitation, (3)convenient transportation, (4)a natural disaster, (5)thief(public order), (6)refuge from a war & escaping from a troubled society, (7)feeling from a place, and (8)Jang-gi(poison coming from earth).

• 대한임상독성학회지
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• 제15권2호
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• pp.101-106
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• 2017

Purpose: This study examined the patterns of drugs, poisons, and chemicals detected in autopsy samples performed in the Seoul Institute and other regional forensic offices of the National Forensic Service (NFS) between 2014 and 2016. Methods: The investigation carried out using the laboratory information management system. Forensic toxicological identification and quantitation were performed in autopsy samples, including heart blood, peripheral blood, liver, kidney, vitreous humor and etc. Gas chromatography/mass spectrometry (GC-MS) and liquid chromatography-tandem mass spectrometry (LC-MS/MS) were used to analyze the drugs and poisons. Results: Forensic autopsies were performed on 9,674 cases in this period. Based on the autopsy reports, 699 cases (7.2%) were considered as unnatural deaths caused by fatal intoxication. The number of male deaths was higher than that of female deaths, with the age of 50-59 being the most common age group. Conclusion: Drugs comprised the largest number of deaths due to poison, followed by alcohol, agrochemicals, drug with alcohol, carbon monoxide, and cyanide, in that order. Zolpidem was the most frequently used drug in all drug-related intoxication cases.

• 한국인공지능학회지
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• 제10권1호
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• pp.9-14
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• 2022

The demand for public bicycles operated by the Seoul Metropolitan Government is increasing every year. The size of the Seoul public bicycle project, which first started with about 5,600 units, increased to 3,7500 units as of September 2021, and the number of members is also increasing every year. However, as the size of the project grows, excessive budget spending and deficit problems are emerging for public bicycle projects, and new bicycles, rental office costs, and bicycle maintenance costs are blamed for the deficit. In this paper, the Azure Machine Learning Studio program and the Boosted Decision Tree Regression technique are used to predict the number of public bicycle rental over environmental factors and time. Predicted results it was confirmed that the demand for public bicycles was high in the season except for winter, and the demand for public bicycles was the highest at 6 p.m. In addition, in this paper compare four additional regression algorithms in addition to the Boosted Decision Tree Regression algorithm to measure algorithm performance. The results showed high accuracy in the order of the First Boosted Decision Tree Regression Algorithm (0.878802), second Decision Forest Regression (0.838232), third Poison Regression (0.62699), and fourth Linear Regression (0.618773). Based on these predictions, it is expected that more public bicycles will be placed at rental stations near public transportation to meet the growing demand for commuting hours and that more bicycles will be placed in rental stations in summer than winter and the life of bicycles can be extended in winter.

• 전자공학회논문지
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• 제51권9호
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• pp.238-247
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• 2014

착유로봇 시스템은 움직이는 젖소의 유두 위치를 정확하게 검출해야 하고, 로봇 매니퓰레이터는 검출된 유두 위치값을 추적하여 착유컵이 유두에 장착하도록 제어되어야 한다. 제안된 착유로봇 매니퓰레이터는 위치검출 레이저 센서를 이용하여 유두를 스캐닝하고 임베디드 구동제어장치를 통하여 독립된 3축 브러쉬리스 서보 구동제어 메커니즘에 의하여 구현된다. 이 로봇 매니퓰레이터는 유두 위치검출용 레이저센서, 4개의 착유컵, 3축 x, y, z축의 매니퓰레이터, g축 방향 이송기능을 가진 유두인 식장치와 착유컵 구동장치, 임베디드 구동제어장치와 자동 밀크 제어라인으로 구성된다. 제안된 로봇시스템은 구동시스템 전체가 전기구동방식으로 설계되어 있기 때문에 구조가 간단하고, 저가로 제작이 가능하며, 구동시에 소음이 적기 때문에 젖소의 심적 안정성을 줄 수 있는 장점을 가지고 있다. 설계된 로봇은 축산과학원 농장에서 젖소를 대상으로 실험을 실시하였으며, 실험결과에 의하여 설계사양의 성능조건이 만족됨을 확인하였다.