• Journal of Korean Society of Environmental Engineers
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• v.31 no.2
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• pp.90-95
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• 2009

Sludge pre-treatment utilizing cavitation is one of the commercialized methods at present. Cavitation can be generated by two different methods, sonotrode and hydrodynamic principle, and there has been no direct comparison between the two methods. In this study, solubilization efficiency, changes in sludge size distribution, and the methane production potential after pre-treatment by the two methods were compared. The maximum solubilization efficiency per unit energy input with the two methods was similar, and was 302 mg ${\Delta}SCOD/g$ TS at the energy input of 0.18 kWh/L. Break-up of sludge flocs were dominant during the early period of pre-treatment, while cell disintegration continued through the pre-treatment with the increase in the number of particles with less than 1 ${\mu}m$. BMP test results indicated that the methane potential increased up to 24.3% without differences between the two pre-treatments, and the increase in methane potential did not proportional to energy input. Although the energy efficiency of the two methods was quite similar, hydrodynamic methods might be a better choice for field application considering the operation and maintenance cost, and its potential improvement in energy efficiency.

• Korean Journal of Food Science and Technology
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• v.29 no.3
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• pp.492-496
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• 1997

Purple sweet potato pigment extract was concentrated using both membrane separation method and vacuum concentration method. The pigment extract (anthocyanin content 1.6 g/L) was concentrated $({\times}25)$ after 5 hr of continuous operation of a nanofiltration to get anthocyanin content of 10.6 g/L. Total solid content also increased continuously while the flux decreased continuously during the concentration process. Degradation index (DI) changes of concentrated pigment solution were insignificant during the whole concentration process which is indicating that the nanofiltration method does not affect color degradation of anthocyanin pigment. For the comparison test, the same pigment extract was concentrated using a rotary vacuum evaporator at temperatures of 40 and $60^{\circ}C$. At both temperatures, pigment content increased in a similar manner during concentration $({\times}5)$. However, DI value at $60^{\circ}C$ increased while that at $40^{\circ}C$ did not change appreciably. Total color difference value changed only slightly by nanofiltration and $40^{\circ}C$ while changed significantly by $60^{\circ}C$. These indicate that a membrane filtration method is more effective in concentrating purple sweet potato pigment extract than a vacuum concentration method by high temperature.

• Journal of the Korea Society for Simulation
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• v.24 no.4
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• pp.1-9
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• 2015

As the use of software is more wider in the safety-critical nuclear fields, so study to improve safety and quality of the software has been actively carried out for more than the past decade. In the nuclear power plant, nuclear man-machine interface systems (MMIS) performs the function of the brain and neural networks of human and consists of fully digitalized equipments. Therefore, errors in the software for nuclear MMIS may occur an abnormal operation of nuclear power plant, can result in economic loss due to the consequential trip of the nuclear power plant. Verification and validation (V&V) is a software-engineering discipline that helps to build quality into software, and the nuclear industry has been defined by laws and regulations to implement and adhere to a through verification and validation activities along the software lifecycle. V&V is a collection of analysis and testing activities across the full lifecycle and complements the efforts of other quality-engineering functions. This study propose a methodology based on V&V activities and related tool-chain to improve quality for software in the nuclear power plant. The optimized methodology consists of a document evaluation, requirement traceability, source code review, and software testing. The proposed methodology has been applied and approved to the real MMIS project for Shin-Hanul units 1&2.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.15 no.6
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• pp.115-121
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• 2015

In this paper, we proposed an iterative data-flow optimal scheduling algorithm based on genetic algorithm for high-performance multiprocessor. The basic hardware model can be extended to include detailed features of the multiprocessor architecture. This is illustrated by implementing a hardware model that requires routing the data transfers over a communication network with a limited capacity. The scheduling method consists of three layers. In the top layer a genetic algorithm takes care of the optimization. It generates different permutations of operations, that are passed on to the middle layer. The global scheduling makes the main scheduling decisions based on a permutation of operations. Details of the hardware model are not considered in this layer. This is done in the bottom layer by the black-box scheduling. It completes the scheduling of an operation and ensures that the detailed hardware model is obeyed. Both scheduling method can insert cycles in the schedule to ensure that a valid schedule is always found quickly. In order to test the performance of the scheduling method, the results of benchmark of the five filters show that the scheduling method is able to find good quality schedules in reasonable time.

• Journal of Digital Convergence
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• v.14 no.12
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• pp.133-140
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• 2016

The study has been implemented for finding out a revitalization of the social enterprise to be continuously developed. In this research, social enterprise employees residing in JeollaNamdo were selected as the research members. The polled papers had 210 copies of total and 180 copies of recovery. The response results were written as a rule of their own way with advanced visit to them explaining how to write down. The collected data were analysed with T-test and ANOVA. As a result of the research, the system effectiveness of social enterprise is shown to influence the satisfaction of employees. Therefore, it is shown that the certification system and priority purchase system of local government can be effective. Second, it is shown that the satisfaction of employees of the social enterprise influences the satisfaction of employees. Therefore, it is shown that the need of finding out a new business item for a social enterprise to grow influences positively on the satisfaction of employees. Third, operation difficulty of the social enterprise is not shown to influence the satisfaction of employees. In other words, the satisfaction of employees is not influenced by a difficulty arising from not receiving the official recognition from local government on the social enterprise.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.40 no.4
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• pp.191-202
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• 2017

The purpose of this study is to develop an engineer competency model using Analytical Hierarchy Process (AHP) to improve the national technical qualification system. Korea has managed technical human resources at the government level through the operation of a national technical qualification system that certifies engineers with national certificates or technical grades by laws. However, there have been increasing concerns that the government system is separated from global standards and does not reflect an engineer's comprehensive capabilities. For these reasons, the new architecture of the system has been continuously discussed and becomes a major policy issue of the Korean government. For the development of the engineer competency model, domestic and global models were separately structured using 554 valid questionnaires with a consistency ratio (CR) of 0.1 or less. The relative importance of engineer competency factors in a domestic model was career (0.383), qualification (0.253), academic degree (0.195), and job training (0.169) whereas the order in the global model was career (0.308), global ability (0.237), job training (0.175), domestic qualification (0.147), and academic degree (0.134). The results of AHP analysis indicated that the evaluation factors and methods recognized by engineers were different from a current government model focusing on domestic qualifications. There was also perceptual difference in the importance of engineer evaluation factors between groups depending on the type of organizations and markets. This means that it is necessary to reflect the characteristics of organizations and markets when evaluating engineer competency. Based on AHP analysis and literature reviews, this paper discussed how to develop a new engineer competency index (ECI) and presented two effective index models verified by simulation test using 59,721 engineers' information. Lastly, the paper discussed major findings of our empirical research and proposed policy alternatives for the improvement of a national engineer qualification system. The paper contributes to the management of technical human resources since it provides quantitative competency models that are objectively developed by reflecting market recognition and can be effectively used by the policy makers or firms.

• Journal of the Korean earth science society
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• v.25 no.5
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• pp.303-314
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• 2004

The purpose of this study is to analyze high school students' understanding levels about earth science terms written in Chinese characters according to learners' characteristics. In order to investigate how the responses vary according to their characteristics, first of all, proper scientific terms are selected, and then corre sponding questions about them are offered as subjects, which consists of a Korean characters type, a picture type, and a Korean and Chinese characters type. During paper test and interview, the questions are given to fifteen students from general high schools in Jecheon, Chungbuk Province. The results of the study are as follows; Students in formal operation level and field-independency answered very well and also the terms of Chinese characters type and picture type improve the students' understanding and memorization. Generally, Chinese characters have more positive influence on their learning than the negative. Therefore, in general, it seems that it's more effective to explain the sound and meaning of terms in detail and to give learners enough time to draw a picture about each term by themselves when scientific terms are delivered to students in Chinese characters in class.

• Journal of the Korean Electrochemical Society
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• v.13 no.2
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• pp.81-88
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• 2010

Small size polymer electrolyte membrane fuel cell (PEMFC) stacks were prepared using carbon composite and graphite bipolar plates and their performances were evaluated on reactant gas and operating time. In comparison to single cell and stack, it was identified that home-made bipolar plate was well-designed to maximize stack performance as high as that of single cell. During long-term operation, the performances of stacks using two different kinds of bipolar plates were compared. The decrease of performance in both stacks was accelerated with increasing load current. It was observed from stack test that the stack performance using carbon composite bipolar plate was very similar to that using graphite bipolar plate.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• v.31 no.4
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• pp.300-305
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• 2005

Purpose: For the reconstruction of maxillofacial defect created by trauma, infection, or tumor etc, the role of microvascular anastomosis or vessel graft has been increased. Many methods has been tried to increase the success rate of microvascular anastomosis. Various anticoagulants and thrombolytic agents have been used to reduce the failure rate of microvascular anastomosis and avoid re-operation. Many drugs, however, have been used in the limited cases because most of these drugs may cause complications, such as allergy, fever or systemic bleeding. This study was performed to evaluate the influence of the Argatroban on patency and thrombosis in microvascular anastomosis when it is used for local irrigation or general administration. Materials & methods: Eight mature rabbits, weighing 2kg, were used. After exposing both femoral veins, the artificial thrombotic model was made by crushing injury using a smooth needle holder, and the transverse incision were made on femoral vein. The animals were divided into 4 groups according to Argatroban administration methods; control group (n=4), topical irrigation of lumen with saline solution; experimental group 1 (n=4), topical irrigation of lumen with Argatroban saline solution; experimental group 2 (n=4), topical irrigation of lumen with heparin followed by intravenous injection of Argatroban; experimental group 3 (n=4), topical irrigation of lumen with Argatroban followed by IV of Argatroban. Microvascular anastomosis was done with 10-0 Ethilon. The patency was evaluated by empty-and-refill test 30 minutes and 3 days after microanastomosis. The thrombus formation was examined 3 days after microanastomosis by surgical microscope. The histologic findings were also examined. Results: 1. Thirty minutes after microvascular anastomosis, the patency of all experimental groups was better than that of control group, but there was no significant difference among groups. 2. Three days after microvascular anastomosis, the patency of all experimental groups was more improved than that of control group (p<0.05). There was no significant difference among experimental groups. 3. Three days after microvascular anastomosis, the amount of thrombus in all experimental groups was less than that of control group (p<0.05). There was no significant difference among experimental groups. 4. Histologically, a lot of luminal thrombus was observed around sutured area in control group. Few luminal thrombus was observed in all experimental groups. The necrotic changes were observed on the sutured vein wall in all specimens. Conclusion: These results indicate that topical irrigation and/or intravenous administration of Argatroban is effective in improving patency and preventing thrombus formation after microvascular anastomosis.

• The Korean Journal of Air & Space Law and Policy
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• v.26 no.2
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• pp.41-68
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• 2011

This article deals with the current rules of law of air warfare and its surrounding issues on precautionary action by a military aircraft at air-to-air operation in international armed conflict. However there is no separate and independent legal system to regulate warfare in aerospace in the current system of law of war (or law of armed conflict). In other words, law of air warfare does not exist in a form of a separate treaty. Air warfare has been regulated by international customary law and the relevant provisions in different Conventions, including 1949 four Geneva Conventions and two Additional Protocols, which mainly regulate land and naval warfare. And this makes difficult to make clear a legal term or legal tests on an issue concerned with law of air warfare, which concludes from time to time a dispute on interpretation and implementation of law of air warfare between states. Therefore, this article refers various materials (including 1949 Geneva Conventions and Additional Protocols, San Remo Manual, Harvard Manual, and ICAO Manual on Interception of Civilian Aircraft) for the purpose of defining the current and desirable legal test on precautionary action by military aircraft. In addition to the main purpose of this article, this article tried to show a characteristic of developing mechanism of law of air Warfare taking into account interactions between international air law and law of air warfare.