• The Transactions of The Korean Institute of Electrical Engineers
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• v.60 no.1
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• pp.8-13
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• 2011

A percentage current differential relay is widely used for transformer protection. Because many percentage current differential relays recently use modified methods instead of conventional methods for deciding the operating characteristics of the large current region, in this paper, the operating region of a percentage current differential relay is analyzed in input-output current domain instead of operating-restraint current domain. An effective method to set the operating region when a CT is saturated is proposed with a series of investigations comparing a conventional method with the proposed modified method. The performance of the proposed method is evaluated for internal and external faults of a power transformer having the voltage rating of 345/154kV. EMTP-RV is used for the relaying data collection.

• Journal of Advanced Navigation Technology
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• v.27 no.5
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• pp.534-539
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• 2023

Currently, in Korea, to obtain a jet type rating, you must receive training on a small business jet model. The reason is because of the law in the Aviation Safety Act Enforcement Rules 『Appendix 4』 that states, "You must receive at least 2 hours of flight training." In the end, it is acquiring type rating as a small business jet aircraft with relatively low operating costs. The qualifications acquired in this way are different from those for aircraft operated by airlines. However, if you have an initial jet type rating, you can acquire an airline aircraft qualification just by training on a simulator, so airlines want you to have at least a small-jet type rating. However, in the United States and Australia, there is a system in place to acquire initial jet type rating through simulator training without actual flight training.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.30 no.11 s.254
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• pp.1093-1100
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• 2006

Combustion stability rating of jet injector is conducted numerically using air-injection technique in a model chamber, where air is supplied to oxidizer and fuel manifolds of the model five-element injector head. A sample F(fuel)-O(oxidizer)-O-F impinging-jet injector is adopted. In this technique, we can simulate mixing process of streams flowing through oxidizer and fuel orifices under cold-flow condition without chemical reaction. The model chamber was designed based on the methodologies proposed in the previous work regarding geometrical dimensions and operating conditions. From numerical data, unstable regions can be identified and they are compared with those from air-injection acoustic and hot-fire tests. The present stability boundaries are in a good agreement with experimental results. The proposed numerical method can be applied cost-effectively to stability rating of jet injectors when mixing of fuel and oxidizer jets is the dominant process in instability triggering.

• The Journal of the Acoustical Society of Korea
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• v.37 no.5
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• pp.331-337
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• 2018

In this paper, we apply the NR (Noise Rating) to the evaluation of the residual noise of the window type ANC (Active Noise Control) and study the active noise controller for minimizing the NR value in rooms. We proposed a shape of a noise shaping filter of the Filtered-E LMS (Least Mean Square) algorithm that reduces the NR value within the effective operating frequency band of the ANC. The usefulness of the proposed scheme is verified by simulation and showed that the NR value of the residual noise is lower than the filters used in the conventional psychoacoustic ANC.

• 한국태양에너지학회:학술대회논문집
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• 2011.04a
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• pp.138-143
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• 2011

Until now, measures for energy saving in buildings have been tried. Because particularly the role of buildings area is very important for implementing national greenhouse gas reduction targets and Green growth. But, lack of business linkages between each sector or the interest and participation of private sector are not enough. In addition, relevant personnel to do had not been systematized. It is expected that certification services will be increased according to the activation of Building Energy Efficiency Rating System and expansion of the target buildings so Government must be prepared to expand of certification system by training Professional staff. In this study, the basic data for the introduction of obligation of Building Energy Efficiency Rating System is suggested through analysis of the operating and laws system of Building Energy Efficiency Rating System along with efforts of Government for diffusion low energy buildings.

• Management & Information Systems Review
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• v.34 no.5
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• pp.213-231
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• 2015

In this paper, I examine whether the listed companies in Korea tend to manage operating cash flows upward via classification shifting after the adoption of K-IFRS. As proxies for cash flow management, I derive a measure of abnormal operating cash flows borrowing from Lee(2012). Alternative proxies include a series of categorical variables designed to identify the types of classification shifting of interest and dividend payments among others, in the statement of cash flows. Higher level of estimated abnormal operating cash flows, and the classification of interest/dividend payments in non-operating activity sections are considered to indicate the managerial intention to maximize reported operating cash flows. I consider several potential incentives to manage operating cash flows, which include financial distress, the credit rating proximity to investment/non-investment cutoff threshold, avoidance of negative or decreasing operating cash flows relative to previous period and so forth. In a series of empirical analyses, I do not find evidence in support of the opportunistic classification shifting explanation, inconsistent with several previous literature in Korea. In contrast, I observe negative associations between the CFO management proxies and selected incentives, which suggest that the classification is likely to represent above average cash flow performance rather than opportunistic motives exercised to maximize reported operating cash flows. I reckon that this observation is, in part, driven by the K-IFRS requirement to maintain temporal consistency in classifying interest and dividend receipts/payments in cash flow statement.

• Proceedings of the Korean Nuclear Society Conference
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• 2005.05a
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• pp.825-826
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• 2005

• Cartoon and Animation Studies
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• s.33
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• pp.551-578
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• 2013

Since October 2006, number of deliberations of arcade game in Game Rating Board (GRB) annually was more than 1,000 cases except 2007 and 2010. However, these cases excessively handle to deliberate the game rating. Especially, the rating is manually performed thus, hindering the consistency and objectivity of the deliberation. To resolve this problems, we think that the automation of technical deliberation is necessary for arcade game which is needed to have much time for deliberation. The purpose of this study is to identify what the possibility part of automation or what obviously part of automation in the deliberation of game rating. To achieve our research purposes, we conducted in-depth interview with GLI standardization expert in BMM Korea and person in charge for deliberation in game rating board. The interview results show that 12 standardization and 14 automation factors for deliberation in game rating of arcade game. This study will expect bases in game development and promotion in game industry.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.57 no.11
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• pp.1922-1928
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• 2008

The thermal rating of a conductor are maximum continuous current capacity and short time emergency current capacity. The overload operation for a faults have an effect on a conductor lifetime. Its time duration and overload level are limited to facility conditions of transmission lines. The short time emergency current capacity in KOREA observe the KEPCO's DESIGN RULE 1210, but its rules are not included to concept of an allowable short time duration. This papers are described to the calculation concept of short time emergency current capacity considering a time duration and an overload level. And we suggested a operation grouping and its maximum conductor temperature considering facility conditions - conductor lifetime, stability of connection points, conductor height above ground and clearance, in the operating and new T/L.

• Imaging Science in Dentistry
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• v.30 no.3
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• pp.155-158
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• 2000

The purpose of this paper is to explain the making procedure and the usage of receiver operating characteristic (ROC) curve for interpretation of radiographic images. The conventional radiograms obtained after the creation of the lesions in the acrylic plates and were enhanced in color. The observer were informed of which tooth to examine, the 'a priori' probability of a lesion present and the approximate diameter of the lesions. The two groups of films were interpreted separately by the same observer using the same rating scale. The following rating scale was used: A; definitely no lesion, B; probably no lesion, C; not sure, D; probably a lesion, and E; definitely a lesion. In analysis, for each observer the diagnostic results in terms of true positive (TP) and false positive (FP) decisions were plotted on a graph. The lowest point on the graph represents the TP and FP when only decisions designated as E according to the rating scale are included. The next point shows the TP and FP values when diagnoses designated as D are added and so forth. By connecting such plot points, a receiver operating characteristic (ROC) curves is obtained. The area under the curve represents the diagnostic accuracy resulting from a diagnostic performance at pure chance level and a value of 1.0 at perfect performance. This method has been known as an useful method to detect the minute difference for each radiographic technic, each observer and for the different lesion depths.