• Proceedings of the KIPE Conference
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• 2000.07a
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• pp.572-575
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• 2000

In this paper we studies VVVF inverter for 1C4M propulsion system of urban rail traction. This inverter is consisted of inverter stack DB unit and control unit. To prove performance of inverter carry out main track test. From test for VVVR inverter verifies excellent performance

• Proceedings of the Korean Institute of Building Construction Conference
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• 2015.11a
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• pp.200-201
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• 2015

The unit modular method is one in which unit modules are prefabricated at a factory and then constructed at a construction site. That is why an important process, transporting unit module, is added in this method. The purpose of this study is to analyse the load for transporting unit module. The results of the analysis of the driving experimental runs revealed that a maximum load of 15 kN was applied on adapter block type A and a maximum load of 25 kN on adapter block type B. These loads were recorded at the points in the road test when the low-bed trailer was driving through unstable sections of the test such as stopping, restarting, passing over a speed bump or taking a left turn at speed.

• The Korean Journal of Applied Statistics
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• v.24 no.1
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• pp.35-43
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• 2011

In this paper, we introduce a unit root test via discrete cosine transform in the AR(1) process. We first investigate the statistical properties of DCT coefficients under the stationary AR(1) process and the random walk process in order to verify the validity of the proposed method. A bootstrapping approach is proposed to induce the distribution of the test statistic under the unit root. We performed simulation studies for comparing the powers of the Dickey-Fuller test and the proposed test.

• The KSFM Journal of Fluid Machinery
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• v.15 no.5
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• pp.20-26
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• 2012

An APU(Auxiliary Power Unit) for helicopters has been developed in Korea and tested at the AETF(altitude engine test facility) in KARI(Korea Aerospace Research Institute) for the purpose of the military qualification. A cell correlation test was performed before the official test, and the results are within the tolerance. The APU has the capability of supplying electric power as well as compressed air to the helicopters. It was tested at bleed extraction conditions, electric power extraction conditions, and maximum continuous concurrent power conditions within the entire helicopter flight envelop. Some special test equipments were implemented for the measurement of air flowrate, electric power and so on. The tests were successfully performed and their results satisfy the requirements of the helicopters.

• Journal of the Semiconductor & Display Technology
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• v.11 no.2
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• pp.59-62
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• 2012

This test method covers a procedure for measuring particle removal characteristic of equipment fan filter unit(EFFU) installed inside of semiconductor process equipments, FPD manufacturing equipments and so on. Since EFFU is a combination of air filter and the assembly of fan, motor and frame, the integrity of these parts is very important for the performance of EFFU. So a conventional particle removal test method for air filters is not suitable for EFFU particle removal performance. This test method defines an evaluation method for EFFU which is installed inside an enclosed space to remove particles that are generated inside process equipment. The particle removal performance of EFFUs is usually depending on the performance of filter media and air flow rate. To understand a performance of an EFFU, the filter media characteristic, air flow rate and the integrity of EFFU parts should be considered simultaneously. This test method is intended to demonstrate the system performance of an EFFU and successfully evaluated EFFU performance characteristics.

• Journal of the Korean Society of Environmental Restoration Technology
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• v.11 no.4
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• pp.119-128
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• 2008

In this study, we attempted to seek out the ways to recycle fresh root-chips in the slope revegetation works by breaking tree root wastes occurring during the construction works, also to review the applicability of fresh root-chips as the soil media in slope revegetation works. For this purpose, we organized test units in order to investigate on-site applicability of fresh root-chips (broken chips). In order to examine the desirable ration of combining fresh root-chips with the hydroseeding soil media on the cutting slopes, we organized test units depending on the amount of combination. The following is the main experimental results. 1. At first, we analyzed properties of hrdro-seeding soil media and soil of the experimental sites. The overall results demonstrate that all the test units show proper range for vegetation. 2. We believe that the physical properties of soils in the earlier phase of restoration works on the sloped sites are not greatly affected by the fact whether broken chips exist or not. However, as time elapses, broken chips needs to be investigated further on what kind of impact they have on the soil condition. 3. More species are found in the test unit combining broken chips and we believe that it will contribute to blossoming of green plants and ecological succession of neighboring plants. 4. We performed experiment on possibility for fresh root-chips as substitutes for the hydro-seeding soil-media. In the test unit that combines fresh root-chips, its mixture ratio tends to exceed that of the test unit that does not combine fresh root-chips by 5 %. In case of the Thick-Layer-Soil-Media Hydroseeding works, the mixture ratio of the test unit that combines fresh root-chips after 16 weeks exceeds that of the test unit that does not combine fresh root-chips by 75%. 5. From the result of our experiment, it is obvious that the ratio of mixture and the number of emerging species are higher for the test unit combining fresh root-chips than the test unit that does not combine them. In other words, we can replace the hydro-seeding-soil-media with some Fresh root-chips without affecting the physical property of soil.

• Korean Journal of Clinical Pharmacy
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• v.24 no.1
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• pp.9-14
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• 2014

Background: It is known to reduce the mortality when glutamine is supplied to patients during the surgery or in intensive care unit through intravenous nutrition supply. The purpose of this study is to establish the appropriate basis for use of glutamine and guidelines of nutrition supply for critically ill patients in the hospital by examining the clinical effects of administration of glutamine with subjects of elderly critically ill patients receiving intravenous nutrition in one hospital in Korea. Method: Among elderly patients with age of 60 or more hospitalized in Yeuido St. Mary's Hospital from August 2012 to July 2013, those who stayed in the intensive care unit for more than a week and received TPN (Total Parenteral Nutrition) for more than 3 days during staying in the intensive care unit were classified to a test group using glutamine and a control group without glutamine. Duration of use of mechanical ventilator, duration of hospitalization, occurrence of infectious disease and death were compared between two groups. We would like to identify the clinical test figures affected by the use of glutamine by examining changes in SCr, Total Protein, Albumin, AST, ALT, TB, DB and GFR at the time of admission and discharge. Results: At the time of admission to intensive care unit, gender, physical measurement information and clinical test figures did not show any significant difference between 72 subjects in a test group and 24 subjects in a control group. Thus, two groups began in the same condition. There were no significant difference in duration of hospitalization, duration of intensive care unit, use of mechanical ventilator, occurrence of infectious disease and death. As the results of statistical analysis of the average changes of clinical test figures at the time of admission and discharge of intensive care unit, SCr and GFR were significantly changed in the test group. GFR was significantly changed in a control group. As the result of analysis of the clinical test figures at the time of discharge with reflection of average changes after clinical test figures were corrected at the time of admission of intensive care unit, TB and GFR were significantly increased in a test group compared with those in a control group. Other clinical test figures were not significantly changed. Conclusion: If glutamine is administered to critically ill patients over age 60 receiving TPN and careful monitoring for total bilirubin is made in the future, it is expected to give the positive effect on renal function andminimize the side effect of arise in total bilirubin.

• The Mathematical Education
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• v.57 no.1
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• pp.37-54
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• 2018

Despite the significance of fraction in elementary mathematics education, it is not easy to teach it meaningfully in connection with real life in Korea. This study aims to investigate and analyze 3rd grade students' understanding on unit fraction concepts and on comparison of unit fractions and to identify the parts which need to be supplemented in relation to unit fraction. For these purposes, I reviewed previous studies and extracted chapters which cover unit fractions in elementary mathematics textbooks based on 2009 revised curriculums and analyzed teaching contexts and visual representations of unit fractions. From this point of view, I constructed a test which consists of three problems based on Chval et al(2013) to investigate students' understanding on unit fraction. To apply this test, I selected forty-one 3rd grade students and examined that students' aspects of understanding on unit fraction. The results were analyzed both qualitatively and quantitatively. In this study, I present the analysis results and provide implications and some didactical suggestions for teaching contexts and visual representations of unit fraction based on the discussion.

• Journal of the Korean Statistical Society
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• v.26 no.3
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• pp.397-405
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• 1997

Recently maximum likelihood estimators using unconditional likelihood function are used for testing unit roots. When one wants to use this method the determinant term of initial values in the multivariate unconditional likelihood function produces a complicated function of the elements in the coefficient matrix and variance matrix. In this paper an approximation of the determinant term is calculated and based on this aproximation an approximated unconditional likelihood function is calculated. The approximated unconditional maximum likelihood estimators can be used to test for unit roots. When multivariate process has one unit root the limiting distribution obtained by this method and the limiting distribution using exact unconditional likelihood function are the same.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.35 no.4
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• pp.353-362
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• 2007

Unlike large satellites, small satellites, such as nanosatellite and microsatellite, can provide a limited interior space for components mounting. In order to mitigate this issue, the compact Bus Electronic Unit(BEU) that integrates satellite electronic modules, combining most of bus subsystems and payload electronic modules into one unit, has been developed for HAUSAT-2 nanosatellite. This paper addresses the design and environmental test result analyses of BEU. The vibration and thermal vacuum tests were conducted at qualification level for the verification of design margin of newly developed BEU. The performance of individual electronic subsystem modules has been verified through performance tests before and after the qualification tests. It was confirmed that the natural frequency of BEU satisfies the design stiffness requirement without structural damage in the vibration test. Thermal analysis results were also almost consistent with test results through modified thermal analysis modeling.