• International Journal of Aeronautical and Space Sciences
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• v.18 no.2
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• pp.222-235
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• 2017

In this study, finite element modeling was used to predict the material properties of tri-axially braided textile composite. The model was made based on an experimental test specimen which was also used to compare the final results. The full interlacing of tows was geometrically modelled, from which repeating parts that make up the whole braid called unit cells were identified based on the geometric and mechanical property periodicity. In order to simulate the repeating nature of the unit cell, periodic boundary conditions were applied. For validation of the method, a reference model was analyzed for which a very good agreement was obtained. Material property calculation was done by simulating uniaxial and pure shear tests on the unit cell. The comparison of these results with that of experimental test results showed an excellent agreement. Finally, parametric study on the effect of number of plies, stacking type (symmetric/anti-symmetric) and stacking phase shift was conducted.

• Proceedings of the Korean Geotechical Society Conference
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• 2005.03a
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• pp.1167-1174
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• 2005

This paper describes on the volume change of Sewage Dredged Soils by using laboratory test and volumetric change test. The tremendous change of Moisture Content occured in the Sewage Dredged Soils during the Elapsed Time. The Unit Weight increases during the normally shrinkage limit void ratio and then the unit weight decrease. A volume of Sewage Dredged Soils according to the moisture content is a difference maximum 2.5 times. And there is the difference 3.5 times according to the change of unit weight. Therefore, the moisture content and unit weight computation are very important for the computation on the volume of Sewage Drdeged Soils.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2003.06a
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• pp.1046-1050
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• 2003

In this paper, we describe study on the development or multi-path ultrasonic gas flowmeter using a transit time method. This system includes 5 pairs of ultrasonic transducers. ultrasonic signal processing unit using switch matrix method, computation algorithm of gas flow rate, spool piece type multi-path pipe unit. We have developed enhanced type of main ultrasonic signal processing unit using switch matrix method fer multi-path ultrasonic gas flowmeter. Also, we have developed the new transmitting ＆ receiving method of ultrasonic waves and the new signal processing algorithm for the computation of ultrasonic transit time from received ultrasonic waves. In this study, we have designed more compact signal processing unit compared with the conventional hardware system of multi-path ultrasonic gas flowmeter. We have confirmed its reliability for multi-path ultrasonic gas flowmeter through the laboratory test using calibration system. In the future. we will perform the field test for the developed system in the POSCO gas line.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.18 no.6
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• pp.62-68
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• 2019

In this paper, we describe the design and manufacture of a control system for an automatic loading system that inserts and removes workpieces after machining. The control system was manufactured using DSP for high speed and consists of a power unit, a control unit, a communication unit, and a display unit. We connected the control system to the mechanical system of the automatic workpiece loader to test the characteristics, which allowed us to raise and lower the automatic workpiece loading system to the desired position. The successful test demonstrates that we can use the control system to control the workpiece automatic loading system.

• Proceedings of the IEEK Conference
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• 2001.06b
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• pp.125-128
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• 2001

In this paper, we propose a low power Scan-based Built-ln Self Test based on circuit partitioning and pattern suppression using modified test control unit. To partition a CUT(Circuit Under Testing), the MHPA(Multilevel Hypergraph Partition Algorithm) is used. As a result of circuit partition, we can reduce the total length of test pattern, so that power consumptions are decreased in test mode. Also, proposed Scan-based BIST architecture suppresses a redundant test pattern by inserting an additional decoder in BIST control unit. A decoder detects test pattern with high fault coverage, and applies it to partitioned circuits. Experimental result on the ISCAS benchmark circuits shows the efficiency of proposed low power BIST architecture.

• KIPS Transactions on Software and Data Engineering
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• v.8 no.7
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• pp.289-302
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• 2019

Structural change of time series means that the distribution of observations is relatively stable in the period of constituting the entire time series data, but shows a sudden change of the distribution characteristic at a specific time point. Within a non-stationary long-term time series, it is important to determine in a timely manner whether the change in short-term trends is transient or structurally changed. This is because it is necessary to always detect the change of the time series trend and to take appropriate measures to cope with the change. In this paper, we propose a method for decision makers to easily grasp the structural changes of time series by visualizing the test results based on the unit root test. Particularly, it is possible to grasp the short-term structural changes even in the long-term time series through the method of dividing the time series and testing it.

• Journal of Advanced Navigation Technology
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• v.10 no.2
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• pp.173-180
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• 2006

An airborne radar is an essential aviation electronic system of the aircraft to perform various missions in all weather environments. This paper presents the design, development, and test results of the multi-mode pulsed Doppler radar system test model for helicopter-borne flight test. This radar system consists of 4 LRU units, which include ANTU(Antenna Unit), TRU(Tx Rx Unit), RSDU(Radar Signal & Data Processing Unit) and DISU(Display Unit). The developed technologies include the TACCAR processor, planar array antenna, TWTA transmitter, coherent I/Q detector, digital pulse compression, DSP based Doppler FFT filtering, adaptive CFAR, IMU, and tracking capability. The design performance of the developed radar system is verified through various helicopter-borne field tests including MTD (Moving Target Detector) capability for the Doppler compensation due to the moving platform motion.

• Journal of Korean Critical Care Nursing
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• v.15 no.3
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• pp.88-100
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• 2022

Purpose : This study aimed to identify risk factors for unplanned reintubation after planned extubation and to analyze the clinical outcomes in patients admitted to the intensive care unit after cardiac surgery. Methods : The study examined patients who underwent intubation and planned extubation admitted to the intensive care unit after cardiac surgery between January 1, 2017, and December 31, 2021. The reintubation group comprised 58 patients underwent unplanned reintubation within 7 days of planned extubation. The maintenance group comprised 116 patients who did not undergo reintubation and were matched with the reintubation group using the rational for matching criteria. Data were collected retrospectively from electronic medical records. We used the independent t-test, Mann-Whitney U test, 𝑥²-test, Fisher's exact test, and logistic regression analysis with SPSS/WIN 27.0. Results : The multivariate logistic regression analysis demonstrated that albumin (odds ratio [OR]=0.38, 95% confidence interval [CI]=0.20-0.72), surgery time (OR=1.54, 95% CI=1.20-1.97), PaO₂ before extubation (OR=0.85 per 10 mmHg, 95% CI=0.75-0.97), postoperative arrhythmia (OR=2.82, 95% CI=1.22-6.51), reoperation due to bleeding (OR=4.65, 95% CI=1.27-17.07), and postoperative acute renal failure (OR=2.97, 95% CI=1.09-8.04) were risk factors for unplanned reintubation. The reintubation group had a higher in-hospital mortality rate (𝑥²=33.74, p<.001), longer intensive care unit stay (Z=-7.81, p<.001), and longer hospital stay than the maintenance group (Z=-8.29, p<.001). Conclusion : These results identified risk factors and clinical outcomes of unplanned reintubation after planned extubation after cardiac surgery. These findings should be considered when developing and managing an intervention program to prevent and reduce the incidence of unplanned reintubation.

• Proceedings of the Korea Committee for Ocean Resources and Engineering Conference
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• 2003.10a
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• pp.260-265
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• 2003

Recently there are operating the Floating Vessel with the positioning control unit in ocean. This technology is not open to industrial society as exclusive one. In order to improve technical competition for its domestic product. It is required to develope the relevant product like above subject. This system consist of DGPS System, Unique Analysis, System Network, and Mooring System and so on. Accordingly Model/Field test were carried out to verify its Function / Performance for application of practical product. In this development, we have prepared the successful result to operate the speedy / accurate / stable unit as shown on this subject 'Development of Positioning Control System for Ship and Offshore using the DGPS'. And also it is expected to install this product for ship and offshore unit.

• The Journal of Fisheries Business Administration
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• v.48 no.1
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• pp.51-71
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• 2017

We explore each of the three major domestic fishery product markets in South Korea- Frozen Squid, Frozen Hair tail and Dried Anchovy- to assess whether we can find evidence for Law of One Price (LOP) across the five major cities- Seoul, Dae-Jeon, Dae-Gu, Gwang-Ju and Busan. To achieve our aim, we utilize two different types of unit root tests: Augmented Dickey-Fuller (ADF) and Kwiatkowski-Phillips-Schmidt-Shin (KPSS) unit root test. In each of the three fishery product markets, we find evidence in support of LOP among several cities, which confirms that these markets are integrated to a certain extent. In particular, we find stronger evidence of LOP for Dried Anchovy market relative to the other two fishery product markets. Based on our findings, we argue that the Dried Anchovy market exhibits a greater degree of market integration across the five major cities in South Korea compared to the other two fishery product markets. The greater degree of market integration in the Dry Anchovy market is facilitated by its higher substitutability across cities; taken together these findings show that the market for Dried Anchovy in South Korea is more efficient than the markets for Frozen Squid and Frozen Hair tail.