• Transactions of the Korean hydrogen and new energy society
• /
• v.26 no.2
• /
• pp.105-113
• /
• 2015

In order to accelerate hydrogen society in current big renewable energy trend, it is very important that hydrogen can be transported and stored as a fuel in efficient and economical fashion. In this perspective, liquid hydrogen can be considered as one of the most prospective storage methods that can bring early arrival of the hydrogen society by its high gravimetric energy density. In this study, a small-scale hydrogen liquefier has been designed and developed to demonstrate direct hydrogen liquefaction technology. Gifford-McMahon (GM) cryocooler was employed to cool warm hydrogen gas to normal boiling point of hydrogen at 20K. Various cryogenic insulation technologies such as double walled vacuum vessels and multi-layer insulation were used to minimize heat leak from ambient. A liquid nitrogen assisted precooler, two ortho-para hydrogen catalytic converters, and highly efficient heat pipe were adapted to achieve the target liquefaction rate of 1L/hr. The liquefier has successfully demonstrated more than 1L/hr of hydrogen liquefaction. The system also has demonstrated its versatile usage as a very efficient 150L liquid hydrogen storage tank.

• The Journal of the Korea Contents Association
• /
• v.10 no.11
• /
• pp.262-274
• /
• 2010

In Welfare Center for the disabled, under the Government's information acceleration plan, the computer system has been developed starting from work standardization in 2001 but it has been emphasized only on the technical and customer convenience side leaving out preparation for the side effects of them. Therefore this article will seek the necessity of personal information protection, legal basis in the Welfare Center for the disabled. Additionally after analyzing current status for the personal security of Welfare Center for the disabled, establishing an alternative plan for personal security policy's way could be addressed. Increasing education for awareness stress of personal information security, and preparing institutional protection apparatus from applying life cycle of personal information would be an alternative plan for personal information protection for Welfare Center for the disabled. Also frequent monitoring of accessing personal information from the computerized system should be achieved. It is impossible to recover damage caused by leak of personal information although post actions are progressed. From this essay, awareness of personal information protection should be newly revised for both the Social Welfare Organization and the Disabled welfare center, and also technical, institutional strategy's action should be arranged.

• Transactions of the Korean Society of Mechanical Engineers A
• /
• v.34 no.9
• /
• pp.1217-1225
• /
• 2010

The possibility of a sodium-water reaction occurring in a conventional single-wall-tube steam generator in an SFR is a major problem. To improve the reliability of a steam generator, a double-wall-tube steam generator that can reduce the possibility of the occurrence of a sodium-water reaction is being developed. Current developments are focusing on improving the heat-transfer capability of a double-wall tube; further, the development of a leak-detection method to detect the occurrence of a sodium-water reaction during the reactor operation is also underway. In this study, new concepts, which will solve the above-mentioned problems, have been developed. Accordingly, a double-wall tube has been designed, fabricated, and mechanically tested for the purpose.

• Journal of the Korean Society for Marine Environment & Energy
• /
• v.19 no.2
• /
• pp.99-110
• /
• 2016

When a riser is damaged, the oil spills to sea. Oil spills cause huge economic losses as well as a destruction of the marine environment. To reduce losses, it is needed to predict spilled oil volume from risers and the excursion of the oil. The present paper simulated the oil spill for a damaged riser using open source libraries, called Open-FOAM. To verify numerical methods, jet flow and Rayleigh-Taylor instability were simulated. The oil spill was simulated for various damaged leak size, spilled oil volume rates, damaged vertical locations of a riser, and current speeds. From results, the maximum excursion of the spilled oil at the certain time was predicted, and a forecasting model for various parameters was suggested.

• Journal of the Korea Society of Computer and Information
• /
• v.17 no.3
• /
• pp.77-83
• /
• 2012

As web pages provide various services, the distribution of malware via the web pages is being also increased. Malware can make personal information leak, system mal-function and system be zombie. To protect this damages, we should block the malicious web pages. Because the malicious codes embedded in web pages are obfuscated or transformed, it is difficult to detect them using signature-based approaches which are used by current anti-virus software. To overcome this problem, we extracted features to classify malicious web pages and benign ones by analyzing web pages. And we propose a classification method using SVM which is widely used in machine learning. Experimental results show that the proposed method is better than other methods. The proposed method could classify malicious web pages correctly and be helpful to block the distribution of malicious codes.

• Journal of Convergence for Information Technology
• /
• v.10 no.11
• /
• pp.332-339
• /
• 2020

This study aims to analyze problems and deduce improvement plans for information security support policies for SMEs in Korea. To this end, an effective support policy necessary for reinforcing cyber safety nets to enhance the level of information security of domestic SMEs based on the analysis results by analyzing the status and problems of the previous research review and analysis, the current status of information security of SMEs and the information security support policies of major SMEs at home and abroad. I would like to suggest improvement measures. Reinforcement of awareness, legal basis, voluntary capacity building, joint response system, professional manpower and budget support, cyber security construction, untact era support, and regional strategic industry security internalization were suggested. This can be used as the government's information security support policy to raise the level of information security of SMEs in preparation for the post Covid19.

• Convergence Security Journal
• /
• v.17 no.2
• /
• pp.3-13
• /
• 2017

In the knowledge-information society, many domestic companies put lots of investment in technical development to possess core technologies and intellectual property. However, in the results of passive investment in security to protect their technologies compared to the active investment in technical development, the technology leaks from many companies and research institutes are rapidly increasing. Such increase of technology leaks not only causes damage to companies, but also has harmful effects on national economy directly and indirectly. Even though it has been perceived that a lot of industrial technology leak crimes are committed by former/current workers of small and medium-sized businesses, it is hard to find researches that mainly compare and analyze them. Therefore, this study aimed to understand the actual status of industrial technology leaks by analyzing cases of industrial technology leaks from 2014 to 2016 based on the type of victimized companies, corporate internal leakers' positions, matter of complicity, tools used for technology leaks, and motivation for technology leaks. Through the analysis in each type, the patterns and characteristics of industrial technology leaks were researched, and also the exploratory research on industrial security for the prevention of industrial technology leaks was conducted.

• Journal of the Korea Institute of Information Security & Cryptology
• /
• v.20 no.2
• /
• pp.91-108
• /
• 2010

Universities are one of leading R&D institutes, however, their scarce security investment allows research information to leak outside. This paper proposes methods for improving security level of academic institutes to protect research information by analyzing security awareness and activities. To do that, we verified the current status of information security and awareness level by analyzing the survey which was conducted for a member of Seoul National University. As a result of statistical analysis using correlation, analysis of variance, multi regression and so on, we concluded that it is essential to improve security awareness, activities, professor's security level and management process for research labs. Thus, we suggest the following methods, security awareness and knowledge development through education, security management for research labs through provision, introduction of data protection softwares and physical control of visitors which are to be adopted to improve security level.

• Archives of Craniofacial Surgery
• /
• v.21 no.6
• /
• pp.376-379
• /
• 2020

Supraclavicular lymph node (SCLN) flap is a common donor site for vascularized lymph node transfer for the treatment of lymphedema. Chyle leakage is a rare but serious complication after harvesting SCLN flap in the neck. We report a case of chyle leakage at the SCLN donor site and its successful management. A 52-year-old woman underwent SCLN transfer for treatment of lower extremity lymphedema. After starting a regular diet and wheelchair ambulation on the 3rd postoperative day, the amount of drainage at the donor site increased (8-62 mL/day) with the color becoming milky, which suggested a chyle leak. Despite starting a low-fat diet on the 4th postoperative day, the chyle leakage persisted (70 mL/day). The patient was started on fat-free diet on the 5th postoperative day. The amount of drainage started to decrease and the drain color became more clear within 24 hours. The drainage amount remained less than 10 mL/day from the 8th postoperative day, and we removed the drain on the 12th postoperative day. There was no seroma or other wound complications at follow-up 4 weeks after the operation. The current case demonstrates that a fat-free diet can be a first-line treatment for low output chyle leakage after a SCLN flap.

• Archives of Plastic Surgery
• /
• v.49 no.6
• /
• pp.729-739
• /
• 2022

Cranioplasties are common procedures in plastic surgery. The use of tissue expansion (TE) in staged cranioplasties is less common. We present two cases of cranioplasties with TE and systematically review literature describing the use of TE in staged cranioplasties and postoperative outcomes. A systematic review was performed by querying multiple databases. Eligible articles include published case series, retrospective reviews, and systematic reviews that described use of TE for staged bony cranioplasty. Data regarding study size, patient demographics, preoperative characteristics, staged procedure characteristics, and postoperative outcomes were collected. Of 755 identified publications, 26 met inclusion criteria. 85 patients underwent a staged cranioplasty with TE. Average defect size was 122 cm², and 30.9% of patients received a previous reconstruction. Average expansion period was 14.2 weeks. The most common soft tissue closures were performed with skin expansion only (75.3%), free/pedicled flap (20.1%), and skin graft (4.7%). The mean postoperative follow-up time was 23.9 months. Overall infection and local complication rates were 3.53 and 9.41%, respectively. The most common complications were cerebrospinal fluid leak (7.1%), hematoma (7.1%), implant exposure (3.5%), and infection (3.5%). Factors associated with higher complication rates include the following: use of alloplastic calvarial implants and defects of congenital etiology (p = 0.023 and 0.035, respectively). This is the first comprehensive review to describe current practices and outcomes in staged cranioplasty with TE. Adequate soft tissue coverage contributes to successful cranioplasties and TE can play a safe and effective role in selected cases.