• 한국방사선학회논문지
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• 제15권6호
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• pp.919-926
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• 2021

본 연구는 무릎뼈의 변형된 접선 방향 검사 시 최적의 입사각에 대해 알아보고자 하였다. 실험은 Kyoto Kagaku사의 PBU-50 phantom을 이용하여 바로 누운 자세에서 넙다리뼈-정강뼈 각도(Femur-tibia angle, F-T angle)를 95°, 105°, 115°, 125°, 135°, 145°로 각각에서 X선 중심선과 정강뼈가 이루는 각도가 5~20° 되도록 5°씩 변경하여(62.5°, 67.5°, 72.5°, 77.5°, 82.5°, 87°, 87.5°) 무릎뼈 접선 방향 영상을 획득하였다. 영상분석을 위해 Image J를 이용하여 Congruence angle, Lateral patellofemoral angle, Patellofemoral index, 대조도 잡음비(Contrast to noise ratio, CNR)를 측정하였다. 통계 분석은 SPSS 22를 이용하여 일원배치분산분석과 대응표본 t-검정으로 Merchant method와 비교하였다. 연구 결과 Congruence angle의 경우 무릎 각도-X선 중심선의 입사각도가 105°-72.5°(20° 접선조사), 115°-72.5°, 77.5°(15, 20° 접선조사), 125°-82.5°(20° 접선조사), Lateral patellofemoral angle은 115°-72.5°, 77.5°(15, 20° 접선조사), 125°-72.5°(10° 접선조사), Patellofemoral index는 115°-72.5°(15° 접선조사), 125°-72.5°(10° 접선조사)에서 Merchant method와 유의한 차이가 없었다(p>.05). CNR의 경우 105°-67.5°, 72.5°(15, 20° 접선조사), 115°-67.5°, 72.5°, 77.5°(10, 15, 20°접선 조사)일 때 Merchant method와 차이가 없는 것으로 나타났다(p>.05). 본 연구의 결과를 통해 무릎뼈의 변형된 접선방향 검사 시 무릎 각도와 X선관의 입사각도를 각각 115°-72.5°(15° 접선 조사)로 설정함으로써 진단적 가치가 높은 영상을 획득할 수 있음을 확인하였다.

• 한국전자거래학회지
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• 제4권2호
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• pp.81-94
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• 1999

This paper shows the architecture of IPS(Intermarket Payment System), an implementation of the electronic payment function for internet-shopping merchant system. Because the original purpose of commerce transaction is the exchange of money for goods or services, it is very important to prepare an exchangeable economic value or method. The electronic payment system is the hardware or software or both to process an electronic payment transaction. It has two type, the broker type and the electronic value type. The broker type means an intermediator between real bank network and internet commerce transaction. The electronic value type means a substitute for money in the real world. This paper shows the architecture and the function to implement the broker type electronic payment system. The system has two parts. One is the mediator part to support multiple payment systems and to offer common access methods for merchant system database. The other is the executor part to implement the payment protocol and to process payment transaction.

• Journal of Computing Science and Engineering
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• 제5권1호
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• pp.51-70
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• 2011

This paper introduces a new credit card payment scheme called No Number Credit Card that can significantly reduce the possibility of credit card fraud. The proposed payment system is loosely based on Kerberos, a cryptographic framework that has stood the test of time. In No Number Credit Card, instead of card numbers, only payment tokens are exchanged between the customers and merchants. The tokens are generated based on the payment amount, payment type, client information, and merchant information. However, it does not contain the credit card number, so the merchant or a database hacker cannot acquire and illegally use any credit card numbers. The No Number Credit Card system is ideal for online e-commerce transactions and can be used with any credit card that users possess. It can be used with minor modifications to the current card payment system. We provide the principles of its operation through scenario analysis, a sample implementation, and a security analysis

• 수산해양기술연구
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• 제57권3호
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• pp.246-255
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• 2021

Most fishing vessels are less than 100 m in length (LBP), which is not mandatory for the IMO standards for ship maneuverability. Therefore, research on estimating the maneuverability of fishing vessel hull shapes are somewhat lacking compared to that of merchant ship hull shapes, and at the design stage, the numerical simulation method developed for merchant ships are applied without modification to estimate the maneuverability. Since this can cause estimation errors, the authors have derived a modified empirical formula that can improve the accuracy of estimating the maneuverability of fishing vessels in a previous study. In this study, using the modified empirical formula, the IMO maneuverability evaluation items, the turning motion test and Z-test simulations were performed on the fisheries training vessel BAEK-KYUNG and compared with the sea trial test result to verify the validity of the modified empirical formula. In conclusion, the modified empirical formula was able to estimate quantitatively and qualitatively similar to the result of the sea trial test. Such a study on estimating the maneuverability of fishing vessels will be a good indicator for fishing vessel operators and will help them analyze marine accidents.

• International Journal of Naval Architecture and Ocean Engineering
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• 제12권1호
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• pp.918-927
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• 2020

Flows induced by hybrid CRP pod propulsion systems (CRP-POD) are fundamentally characterized by unsteadiness. This work presents a numerical study on the unsteady flow of a CRP-POD at behind-hull condition based on CFD (Computational Fluid Dynamics). Unsteady RANS method is adopted, coupled with SST k-u turbulence model and sliding mesh method. The propeller thrusts and torques obtained by CFD is validated by model tests and acceptable agreements are obtained. The time histories of shingle-blade loads and pressures near the hull surface are recorded for the analysis of unsteady flow features. The cases of forward propeller alone and aft propeller alone are also computed to distinguish the hull-propeller interaction and propeller-propeller interaction. The results show the blade loads of both forward and aft propellers strongly fluctuate with phase angles. For the forward propeller, the blade load fluctuation is mainly governed by the hull-propeller interaction, while the aft blade load is remarkably affected by the propeller-propeller interaction in terms of the load average and fluctuation pattern. The fields of pressure, vorticity and velocity are also analyzed to reveal the unsteady flow features.

• 수산해양교육연구
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• 제4권2호
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• pp.91-100
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• 1992

The name of the Courses of Fishing Technology and of Navigation, as the basic courses in the fisheries high schools and the merchant marine high schools, are unchanged from a viewpoint of keeping a time- honored tradition. According to transition of the industrial structure, the authors tried to examine closely the character, to realize the goal of education, to rationalize the substantial system of the major subjects of each course, and made some concrete proposals of teaching guidance for each subject. The existing 5 compulsory major subjects are reduced to 2, and the subjects of "Sea Training" and of "Fisheries Law" an, disused, and the subject of "Introduction to Ship" and "Introduction to Marine Engine" and "Introduction to Marine Communication" are merged into the "Introduction to Ship". As mentioned above, the level of subject matter become more simplified as well as the students' learning burden is lightened by reduction of the number of major subjects. In conclusion, guiding teachers of major subjects must previously establish the substantial teaching method and carry out the teaching activities taking into consideration of the students' intellectual level and the local requirement on the ground of thorough understanding the character. the goal and the substantial system of each revised subject.

• 수산해양교육연구
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• 제25권3호
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• pp.564-579
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• 2013

The purpose of Maritime Safety Tribunal is that experts about ship operation investigate and reveal causes of marine disasters and suggest plans to prevent recurrence in Korean Maritime Safety Tribunal which is a kind of administrative court. Despite the fact that 72% of marine disasters is fishing vessel accidents and 75% of collision accidents between vessels which most occur is related to fishing boats, it is the very serious problem that there is no any person with licenses of marine technicians for fishing vessels in judges and investigators of Korean Maritime Safety Tribunal. The operational characteristics of fishing vessels, their sizes, and shift patterns of duties in wheelhouses are completely and incommensurably different from those of merchant vessels. By the way, if the investigators and judges who just consist of merchant vessel experts investigate and judge marine accidents about fishing vessels, there could be errors in establishment of policies to investigate and reveal their causes and prevent recurrence of accidents. Especially, in case of collision accidents between fishing vessels and merchant vessels, it is thought that the marine accident interested provides causes which can be doubtful about fairness of judges. Therefore, it is thought that the ratio of judges and investigators is most desirable to compose it to be similar to the occurrence frequency of marine accidents. For this, the following solution plans are suggested. First, qualification for appointment requires first class marine technicians. But there is the only one vessel which needs the first class in fishing vessels. Therefore, it is thought that the provisory clause should be added so that the second class marine technicians can be used instead of the first class ones. Second, the marine accidents of fishing vessels reach 72% but the fact that there is no any judge and investigator with licenses of marine technicians for fishing vessels is thought to go against the purpose of establishment of Korean Maritime Safety Tribunal. Therefore, it is thought that there is, at least, one more judges and investigators in the central and local Korean Maritime Safety Tribunals. The same method should be applied to judge assistants and investigation assistants.

• 한국정보과학회논문지:시스템및이론
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• 제31권5_6호
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• pp.353-359
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• 2004

디지털 형식으로 저장되어 있는 데이타의 불법적인 복사와 재분배는 전자상거래 상에서 데이타를 판매하는 상점에게 매우 큰 문제가 된다. 핑거프린팅 기법은 암호학적인 기법들을 이용하여 디지털 데이타를 불법적으로 재배포한 사용자를 찾아냄으로써 디지털 데이타의 저작권을 보호한다. 익명성이 보장되는 핑거프린팅 기법은 대칭적인 기법과 달리 사용자만이 핑거프린트가 삽입된 데이타를 알 수 있고 비대칭 기법과 달리 데이타가 재배포되기 전에는 사용자의 익명성이 보장되는 기법이다. 본 논문에서는 비밀분산법을 이용한 익명성이 보장되는 새로운 핑거프린팅 기법을 제안한다. 상점은 이전에 배포되었던 데이타를 찾았을 경우, 데이터로부터 재배포자의 신원정보를 추출하여 재배포자의 배포사실을 증명할 수 있다. 또한 등록 시에 Schnorr 서명을 이용하여 고발된 사용자가 범행을 부인할 수 없도록 한다. 제안된 방법은 이산대수문제와 양자간 안전한 계산과정의 안전성에 근거하여 사용자의 익명성이 보장된다.

• 한국마린엔지니어링학회:학술대회논문집
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• 한국마린엔지니어링학회 2005년도 전기학술대회논문집
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• pp.344-347
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• 2005

The cylinder liners of low speed engine are one of a important equipment in merchant ship. But, the precision machining method of cylinder liner is not developed sufficiently. This paper shows a new honing method using by CBN honing stones.

• 수산해양교육연구
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• 제29권3호
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• pp.665-676
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• 2017

Over the past several years, sea trade have increased traffic by ships which highlighted a problem of unwanted species invading the surrounding seas through ship's ballast water discharge. Maritime trade volume has continuously increased worldwide and the problem still exists. The respective countries are spending billions of dollars in an effort to clean up the contamination and prevent pollution. As part of an effort to solve marine environmental problem, BWM(Ballast Water Management) convention was adopted at a diplomatic conference on Feb. 13 2004. In order to comply harmoniously this convention by each country. This convention will be effective after 12 months from the date which 30 countries ratified accounting for more than 35% of the world merchant shipping volume. On Sep. 8 2016, Finland ratified this convention and effective condition was satisfied as 52 states and world merchant vessel fleet 35.1441%. Thus, after Sep. 8 2017, all existing vessels shall be equipped with BWTS(Ballast Water Treatment System) in accordance with D-2 Regulation, which physically handles ballast water from ballast water exchange system(D-1 Regulation). In this study, we analyzed in detail the optimal design method using the Risk Analysis and Evaluation technique which is mainly used in the manufacturing factory or the risky work site comparing with the traditional design concept method applying various criteria. The Risk Assessment Method is a series of processes for finding the Risk Factors in the design process, analyzing a probility of the accident and size of the accident and then quantifying the Risk Incidence and finally taking measures. In this study, this method was carried out for Electrolysis treatment type on DWT 180K Bulk Carrier using "HAZOP Study" method among various methods. In the Electrolysis type, 63 hazardous elements were identified.