• Journal of Institute of Convergence Technology
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• v.3 no.2
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• pp.39-43
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• 2013

Titanium has been used to satisfy various applications such as bio engineering, aerospace, electronics, automobile. Recently, micro fabrication technologies of metals such as titanium have been required to satisfy many conditions in various fields. To satisfy these demands, micro electrochemical process using laser marking can be an alternative method because it is one of the precision machining and efficient process. Micro electrochemical process using laser marking needs to accomplish form of the oxidized recast layer on metal surface by laser marking. The laser beam marking conditions such as average power, pulse repetition rate and marking speed should be properly selected to form oxidized recast layer. So, the characteristics of titanium surface according to laser marking conditions was investigated through SEM(scanning electron microscope), EDS(energy dispersive spectrometer) and surface roughness analysis.

• Journal of Korean Society on Water Environment
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• v.28 no.3
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• pp.426-435
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• 2012

The variation of stream flow is the one of the most important factors which influence on that of water quality in the unit watershed. The target water quality goal is established and permissible load is allotted in the base of the standard flow condition along with its water quality for the management of Total Maximum Daily Loads (TMDLs). A standard flow selected could cause problems in the load allotment if it was not properly arranged. This study reviewed the acquisition of water quality data, the self-variation and the retainability in water quality on the specific flow conditions. This study also proposed the median and the adjusted average flow condition out of general flow conditions as alternative standard flow conditions. It is considered that the alternatives can make the water quality data easily acquired and the water quality representativeness more enhanced on the standard flow conditions.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.28 no.10
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• pp.1172-1177
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• 2004

The emission control of automobile has been intensified as a part of the countermeasure to decrease air pollution in the world. As the cars with an alternative fuel starts to get into the spotlight, the cars with low emission has been introduced and exhaust gas regulation forced in this country. These days, LPG vehicles, which infrastructure of fuel was already built up, and CNG vehicles are recognized for alternative fuel cars in this country. In this study, the constant volume combustion chamber was manufactured and used for experiments to obtain the combustion characteristics of propane mixture. The combustion characteristics was analyzed, with the change of supply conditions of propane fuel. Inside the combustion chamber, the maximum temperature increase with the initial pressure is going up. The burning velocity also seems to have the same characteristic as the temperature. However, the heat flux do not change much according to the theoretical correct mixture but it changes with the various initial temperature of the combustion chamber.

• Journal of Korean Academy of Nursing
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• v.43 no.5
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• pp.669-680
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• 2013

Purpose: This study was done to explore the process of accepting CATs among nurses who experienced CATs in Korea. Methods: Grounded theory methodology was utilized. Data were collected from 10 nurses during individual in-depth interviews. Theoretical sampling was used until the data reached saturation. Data were analyzed using the constant comparative analysis method. Results: The core category emerged as "resolving the doubt and integrating" explaining the process of accepting CATs. The nurses engaged in three stages: need awareness, look for solution and integration. Causal conditions were interest as a nursing intervention and orthodox medical limitations. Context was lack of basis for application and increase in social interest. Strategies were new knowledge acquisition, having a strong will, combined with existing knowledge, and individualized intervention. Intervening conditions were others' eye, exhaustion for nurses and physical environment. Consequences were expanding of the nursing role and improved nurse satisfaction. Conclusion: The results of the study should facilitate application of CATs in nursing practice. To help nurses who are interested in CATs, there is a need for education programs, and further research on CATs.

• Journal of the Korea Institute of Military Science and Technology
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• v.12 no.4
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• pp.460-468
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• 2009

The purpose of this study is propose an alternative for flight attendants to acquire equipment that could enhance the ability to adapt in flying conditions. Introducing and acquiring weapon system, such equipments should be deeply considered in multilateral aspects; reinforcements in the overall strategic status in the army, the ramifications that can contribute to military resources, and economic situations in the country. To do this, we first induced several criteria that can be used for evaluating alternatives. After that, we applied the analytic hierarchy process(AHP) approach to putting all factors into considerations in decision making for equipment acquirement. The results of this study are expected to have usefulness in formulating strategies and policies in selecting equipment acquisition alternatives for flight attendants.

• The Korean Journal of Financial Management
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• v.2 no.1
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• pp.21-34
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• 1986

The purpose of this study is to analyse the risk and uncertainty involved in the capital budgeting which is executed in long periods and requires massive capital expenditure. Under risk and uncertainty conditions, the estimates in the capital budgeting are random variables rather than known constants. Two approaches have emerged in performing economic analysis that explicitly incorporate risk and uncertainty conditions in the analysis. One approach is to develop a descriptive model which describes the economic performance of an individual investment alternative. But no recomendation would be forthcoming from the model. Rather, the decision-maker would be furnished descriptive information concerning each alternative; the final choice among the alternatives would required a separate action. The second approach is to develop a normative model which includes an objective function to be maximized or minimized. The output from the model prescribes the course of action to be taken. Owing to the fact that the normative approach considers the fitness of criteria for decision-making its reasonableness looks better. But it is almost imposible that we correctly and easily derive the individuals' utility function. So within we recognize the limits of the descriptive methods, it is more practicle to analyse the investment alternatives by sensitivity analysis.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.44 no.12
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• pp.1035-1042
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• 2016

By using commercial flight simulation game engine, X-Plane, we have studied QTG(Qualification Test Guide) generation that can satisfy FTD level 5. Flight model is SR-20 of Cirrus. In list of QTG, There are some items to measure control forces. therefore, we have installed CLS(Control Loading System) to flight control devices in order to make it possible to measure control forces. We made Autopilot function externally to make flight model in trim conditions because X-Plane don't provide internal trim routine function. In addition to develop an algorithm, it can automatically perform the test. To avoid the inconvenience to control as it was to be carried out in same conditions. In case of FTD level 5, it is possible to use alternative data sources not only real flight data. By using these alternative data sources, all test results satisfy a scope given by CFR Part 60.

• Journal of Microbiology and Biotechnology
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• v.27 no.4
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• pp.791-807
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• 2017

The type II secretion system (T2SS), which transports selected periplasmic proteins across the outer membrane, has rarely been studied in nonpathogens or in organisms classified as Betaproteobacteria. Therefore, we studied Cupriavidus metallidurans (Cme), a facultative chemilithoautotroph. Gel analysis of extracellular proteins revealed no remarkable differences between the wild type and the T2SS mutants. However, enzyme assays revealed that native extracellular alkaline phosphatase is a T2SS substrate, because activity was 10-fold greater for the wild type than a T2SS mutant. In Cme engineered to produce three Ralstonia solanacearum (Rso) exoenzymes, at least 95% of their total activities were extracellular, but unexpectedly high percentages of these exoenzymes remained extracellular in T2SS mutants cultured in rich broth. These conditions appear to permit an alternative secretion process, because neither cell lysis nor periplasmic leakage was observed when Cme produced a Pectobacterium carotovorum exoenzyme, and wild-type Cme cultured in minimal medium secreted 98% of Rso polygalacturonase, but 92% of this exoenzyme remained intracellular in T2SS mutants. We concluded that Cme has a functional T2SS despite lacking any abundant native T2SS substrates. The efficient secretion of three foreign exoenzymes by Cme is remarkable, but so too is the indication of an alternative secretion process in rich culture conditions. When not transiting the T2SS, we suggest that Rso exoenzymes are probably selectively packaged into outer membrane vesicles. Phylogenetic analysis of T2SS proteins supports the existence of at least three T2SS subfamilies, and we propose that Cme, as a representative of the Betaproteobacteria, could become a new useful model system for studying T2SS substrate specificity.

• Nuclear Engineering and Technology
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• v.41 no.7
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• pp.945-952
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• 2009

The Three Mile Island Unit 2 (TMI-2) accident provides unique full scale data, thus providing opportunities to check the capability of codes to model overall plant behavior and to perform a spectrum of sensitivity and uncertainty calculations. As part of the TMI-2 analysis benchmark exercise sponsored by the Organization for Economic Cooperation and Development Nuclear Energy Agency (OECD NEA), several member countries are continuing to improve their system analysis codes using the TMI-2 data. The Republic of Korea joined this benchmark exercise in November 2005. Seoul National University has analyzed the TMI-2 accident as well as the currently proposed alternative scenario along with a sensitivity study using the Modular Accident Analysis Program Version 4.03 (MAAP4.03) code in collaboration with the Korea Hydro and Nuclear Power Company. Two input files are required to simulate the TMI-2 accident with MAAP4: the parameter file and an input deck. The user inputs various parameters, such as volumes or masses, for each component. The parameter file contains the information on TMI-2 relevant to the plant geometry, system performance, controls, and initial conditions used to perform these benchmark calculations. The input deck defines the operator actions and boundary conditions during the course of the accident. The TMI-2 accident analysis provided good estimates of the accident output data compared with the OECD TMI-2 standard reference. The alternative scenario has proposed the initial event as a loss of main feed water and a small break on the hot leg. Analysis is in progress along with a sensitivity study concerning the break size and elevation.

• Geomechanics and Engineering
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• v.38 no.5
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• pp.529-539
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• 2024

A high-level nuclear waste (HLW) repository is designed for the long-term disposal of high-level waste. Positioned at depths of 500-1000 meters, it offers an alternative to the insufficient storage space for spent fuels, providing a long-term solution. High-level waste emits heat and radiation, causing structural deterioration, including strength reduction and cracks. Therefore, the use of piezoelectric sensors for structural health monitoring is essential for evaluating the safety of the structure over time. Unlike other structures, the HLW repository restricts human access after the disposal of HLW, rendering sensor replacement impossible. Therefore, it is necessary to assess both the lifespan and suitability of sensors under the disposal conditions in the HLW repository. This study employed an accelerated life test (ALT) to assess the sensor's lifespan under disposal conditions. Failure modes, failure mechanisms, and operational limits were analyzed through accelerated stress test (AST). Additionally, the parameters of the Weibull life probability distribution and the Arrhenius accelerated life model were estimated through statistical methods, including the likelihood ratio test, maximum likelihood estimation, and hypothesis testing. Results confirmed that the sensor's lifespan decreases significantly with the increase in the temperature limit of the HLW repository. The findings of this study can be used for improving sensor lifespan through shielding, development of alternative sensors, or lifespan evaluation of alternative monitoring sensors.