• Journal of the Korean Society of Marine Environment & Safety
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• v.23 no.2
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• pp.200-207
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• 2017

The purpose in having a control surface on ships is to control the motion of the ship. The control surface may be composed entirely of a single movable surface or of a combination of fixed and movable portions. A control surface has one sole function to perform in meeting its purpose, and that is to develop a control force in consequence of its orientation and movement relative to the water. The forces and moments generated as a result of this rotation and angle of attack then determine the manoeuvring characteristics of the ship. In this paper, two-dimensional flow characteristics of a flapped rudder and a water-blowing control rudder were accomplished respectively by PIV method in a circulating water channel. Model test has been carried out with different angles of attack of main foil (NACA 0012) and flap's deflection angles to predict the performance of the flapped rudder and the water-blowing control rudder. The 2-frame particle tracking method has been used to obtain the velocity distribution in the flow field. $Re{\fallingdotseq}3.0{\times}10^4$ has been used during the whole experiments and measured results have been compared with each other.

• Fire Science and Engineering
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• v.28 no.4
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• pp.21-28
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• 2014

This study obtained the following results by analyzing the standards related to a $1{\phi}$ 2W MCCB and evaluating its heat resistance characteristics. Since KS C 8321 corresponds to IEC 60947-2 standards, most of the related regulations are similar. The NFPA, which presents the user oriented safety regulations, contains no details about tests or inspections, etc., but it does specify in detail the regulations directly related to safety. It can be seen that KS C 8321 classifies in detail the items about tests and inspections. However, IEC 60947-2 and IEEE C37.51 simplified the test and inspection items or omitted some of them. When applying thermal stress to an MCCB for 6 hours at $180^{\circ}C$ using a heat resistant experimental device, it was found that the actuator lever was transformed and moved in the tripped state. In addition, most of the fixing hanger was melted down, losing their function. When applying thermal stress to the MCCB at $90^{\circ}C$, it showed nothing peculiar, but the fixing hanger was partly deformed at $105^{\circ}C$ and $120^{\circ}C$. It was found that the fixing hanger was deformed and the name plate was discolored at $150^{\circ}C$. It can be seen from the analysis of the internals of the MCCB that the trip bar has been melted away and that the up and down operator has moved up. The experiment performed by applying a withstanding voltage of 6 kV for 60 s showed that all items remained intact. In addition, the evaluation of the insulation performance performed by applying DC 500 V using an insulation-resistance tester showed good insulation performance.

• Journal of the Society of Disaster Information
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• v.16 no.2
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• pp.276-290
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• 2020

Purpose: The construction history of domestic port facilities has been more than 100 years, and until recently, modern facilities have been continuously built and expanded. However, it is not easy to keep the required performance conditions at the time of initial construction due to changes in the marine environment and increase in volume. In particular, in the case of harbor structures that have a long service life, safety performance and function management are becoming very important due to the increase in the size of ships, the increasing frequency of use, and the increase in the scale of natural disasters. Method: Therefore, this study investigates the state change by structural type of port facilities and analyzes the rehabilitation activities and the history that contribute to the performance improvement and life extension activities. Result: Through this, we distinguished between performance improvement cost (CAPEX) and repair maintenance activity (OPEX) that can be used to establish port facility maintenance strategy, and suggested cost model that can be used to establish maintenance strategy. Conclusion: These studies are expected to contribute greatly to mid- to long-term investment decisions.

• Journal of the Korea institute for structural maintenance and inspection
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• v.25 no.3
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• pp.92-99
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• 2021

In the case of precise safety inspection and precise safety diagnosis of a building, a condition evaluation must be conducted to determine the safety grade. Since 2004, an evaluation method using fuzzy theory has been introduced for quantitative condition evaluation,and the relationship and importance of reinforced concrete members using fuzzy theory have been applied. Generally, fuzzy theory is a method used to deal with ambiguous expressions with unclear correlations, but at the time of development, it seems that it was developed by applying fuzzy theory as an alternative in a situation where inspection and diagnosis result data were insufficient. Therefore, it is necessary to verify the relationship and importance of evaluation items derived based on the current fuzzy theory using actual inspection and diagnosis result data.In this study, the correlation between the evaluation items was derived by using the results of 19 precision safety inspections and 9 precision safety inspections and the performance score function formula, and using this, a reasonable durability score calculation formula of the member was presented.

• Korean Journal of Occupational Health Nursing
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• v.4
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• pp.48-57
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• 1995

The purpose of this study was to assess the performance of the role and function of some industrial nurses and to characterize the factors affecting the performance of their activities. Thus the results could be used to suggest the direction in the performance of industrials nurses' activities effectively. During a period from January 10 to March 31, 1994, the data were collected from 87 industrial nurses, who were working as health managers in the plants, in Ulsan city and the vicinity in Kyungnam province, using a structured questionnaire. The results were as follows : 1. The general characteristics of industrial nurses in this study were 82.8% being 30 years old or less, 60.9%, being not married, and 93.1% having eduction levels above junior college. 2. With respect to general work conditions, 94.3% were working in a separate room provided for health care division, 40.2% working under the safety and health department, and 98.9% working as common-level staffs. And 60.9% were working less than 44 hours a week, 70.1% had work experiences less than 5 years, and 50.6% had annual incomes ranging 10 to 14 million wons. 3. As work conditions related to health care activities, 49.4% performed the activities not related to health care as always or occasionally, and 87.4% answered that occupational physicians were appointed in their plant and among them, however, only 6.9% worked on full-time basis and 52.8% perform little activities as occupational physicians. For a decision related to health care activity, 69.0% discussed the problems with the supervisors, and 19.5% made decisions by themselves. 4. As for attitude and perception to their activities as health managers, 66.7% moderately recognized the importance of health manager in the workplace, with 63.2% being satisfied their wages and treatment from the company, 57.5% being satisfied with their job positions and 51.7% having positive attitudes as being health managers. 5. The degree of performance at least in one of health related activities were very high in activities such as general medical care(100%), general health examination(98.0%) and specific health examination(100%), and relatively high in health education(72%), new employee health examination(60.9%), document handling(79.3%) and activity for work environment(70.1%). However, the performance rate was very low in preparing protective equipment (20.8%). 6. The levels of activities related to health care were significantly high when making decisions by themselves, when occupational physicians not being full-time, and when satisfying their job positions, and, on the other hand, significantly decreased as work hours increased. 7. In addition to some kinds of periodic education asked by all of the nurses, 89.7% wanted a specialized licensing system for industrial nurse, and 97.4% wanted to apply for the license test. As a conclusion, it is suggested that industrial nurses should be given more authority and placed in more self-controlled system to perform health care and other activities more efficiently, and the role and function of the occupational physician should be clearly distinguished from that of the industrial nurse as a health manager to avoid an unnecessary overlapping.

• Journal of the Society of Disaster Information
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• v.17 no.1
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• pp.176-183
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• 2021

Purpose: The introduction of smart factories that reflect the 4th industrial revolution technologies such as AI, IoT, and VR, has been actively promoted in Korea. However, in order to solve various problems arising from existing file-based operating systems, this research will focus on identifying and verifying non-file system-based data protection technology. Method: The research will measure security storage that cannot be identified or controlled by the operating system. How to activate secure storage based on the input of digital key values. Establish a control unit that provides input and output information based on BIOS activation. Observe non-file-type structure so that mapping behavior using second meta-data can be performed according to the activation of the secure storage. Result: First, the creation of non-file system-based secure storage's data input/output were found to match the hash function value of the sample data with the hash function value of the normal storage and data. Second, the data protection performance experiments in secure storage were compared to the hash function value of the original file with the hash function value of the secure storage after ransomware activity to verify data protection performance against malicious ransomware. Conclusion: Smart factory technology is a nationally promoted technology that is being introduced to the public and this research implemented and experimented on a new concept of data protection technology to protect crucial data within the information system. In order to protect sensitive data, implementation of non-file-type secure storage technology that is non-dependent on file system is highly recommended. This research has proven the security and safety of such technology and verified its purpose.

• Journal of Microbiology and Biotechnology
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• v.19 no.7
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• pp.718-726
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• 2009

The objective of this study was to develop and validate secondary models that can predict growth parameters of L. monocytogenes Scott A as a function of concentrations (0-3%) of a commercial potassium lactate (PL) and sodium diacetate (SDA) mixture, pH (5.5-7.0), and temperature (4-37DC). A total of 120 growth curves were fitted to the Baranyi primary model that directly estimates lag time (LT) and specific growth rate (SGR). The effects of the variables on L. monocytogenes Scott A growth kinetics were modeled by response surface analysis using quadratic and cubic polynomial models of the natural logarithm transformation of both LT and SGR. Model performance was evaluated with dependent data and independent data using the prediction bias ($B_f$) and accuracy factors ($A_f$) as well as the acceptable prediction zone method [percentage of relative errors (%RE)]. Comparison of predicted versus observed values of SGR indicated that the cubic model fits better than the quadratic model, particularly at 4 and $10^{\circ}C$. The $B_f$and $A_f$for independent SGR were 1.00 and 1.08 for the cubic model and 1.08 and 1.16 for the quadratic model, respectively. For cubic and quadratic models, the %REs for the independent SGR data were 92.6 and 85.7, respectively. Both quadratic and cubic polynomial models for SGR and LT provided acceptable predictions of L. monocytogenes Scott A growth in the matrix of conditions described in the present study. Model performance can be more accurately evaluated with $B_f$and $A_f$and % RE together.

• Korean Journal of Construction Engineering and Management
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• v.10 no.1
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• pp.114-125
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• 2009

In this study, a design value analysis technique that considered stochastic LCC and stochastic performance evaluation was proposed, and by introducing the concept of reliability analysis, a decision making that secured reliability was supported. The results of this study, which was carried out according to the above objectives and methods, are summarized as follows: 1) The design value analysis procedures and value state function, improved in order to carry out a reliable analysis when evaluating alternate proposals that were extracted after the function definition was complete, were formalized, and in order to secure consistency and efficiency for value evaluation procedures, an evaluation index scheme was proposed; 2) Database collection and analysis were done for a bridge's LCC analysis. As for the collection scope of data, literature of previous research done on a bridge's LCC analysis was used as the basis for analysis, and for securing reliability regarding analysis results and dealing with uncertainty of collected data, the MCS technique was applied; 3) Weights and evaluation ranks for performance evaluation of each of the alternate proposals, as well as LCC analysis model, analysis period, discount rate, user expense, safety inspection and safety diagnosis expense conditions for LCC analysis were proposed. Lastly, a feasibility study was done and conclusion was made about "OO grand bridge and connecting road construction work execution design" project centered on value analysis execution case.

• Journal of Korean Society of Transportation
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• v.35 no.5
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• pp.423-433
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• 2017

During recent 5 years, it was recorded that 20% of total accident frequency and 30% of total number of death have been occurred due to drowsy driving. Drowsy driving accident is result from the loss of driving ability due to driver's accumulated fatigue. Continuous driving time can be measured as a surrogate variable to quantify the level of fatigue. The main purpose of this research is to investigate statistical correlation between the proportion of continuous driving vehicle (more than 2 hours) and the number of drowsy accidents. To carry this out, continuous driving time was measured using GPS route-guidance trajectory data. Also, accident frequency, traffic volume and segment length were collected to estimate safety performance function (SPF) for Jungbunearuk expressway in Korea. Through various types of estimated SPFs, statistical correlation was analyzed based on estimated statistical indices. This research can provide theoretical background for enforcement to regulate commercial vehicle driver's continuous driving time. In addition, throughout the trajectory data expansion, it is expected that strategy for anti-drowsy driving facilities installation can be established based on the suggested methodology.

• Journal of the Institute of Electronics and Information Engineers
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• v.49 no.9
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• pp.279-286
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• 2012

Recently, design of Universal Soft Controller(USC) has been applied to the advanced control room for nuclear power plant. USC is software-based manual control means to control safety components as well as non-safety components in the highly-integrated control room. Therefore, design feature of USC is essential for the implementation of a single workstation in the advanced control room. The traditional control room is replaced by computer-driven consolidated operator interfaces. Considering our design has further reduced the probability of USC spurious signals by requiring two distinct operator control actions to generate any control signal. The reality of USC does not increase the probability of reactor trip because the probability of spurious USC signal is negligible. Universal Soft Control represents a significant evolution in nuclear I&C/HSI System. USC integrates the indicators and controls from multiple divisions into a single integrated visual display unit(VDU) based HSI(Human System Interface). In order to prevent adverse influence on safety function performance from USC failure, ESFAS signals are applied to safety components or functions. In addition, safety manual switches have priority over USC's signals. Therefore, spurious USC signals can be momentarily blocked by selecting a soft control command from the safety VDU.