• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.23 no.8
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• pp.967-975
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• 2012

This paper presents a method to measure reflection coefficients of microwave devices or antennas based on time domain analysis with sampling oscilloscopes. The reflection coefficients were extracted by the Fourier transformation of echo pulses from devices with respect to the 20 GHz incident pulse signals. The three-error terms, which are commonly used for the correction of a microwave network, were determined using a 3.5 mm calibration kit. In addition, a modified error-correction model associated with a directional coupler for reflection coefficient measurements is introduced. The results were compared with those of measured with a commercial vector network analyzer.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.37 no.2
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• pp.343-355
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• 2017

In this study, an Assembled Earth Retaining Wall (AER wall) is newly proposed. The AER wall combined stabilizing piles names as Back Supporting Beam is developed to improve stability and economics of existing retaining walls. For the verification of the AER wall, the field model tests and 3D numerical analyses were performed. As a result of the field tests, it can be confirmed that the earth pressure is considerably reduced compared with the L-shaped retaining wall. Also, the 3D numerical analyses show that AER wall is at least 29.85% more effective at lateral displacement than general L-shaped retaining wall. In other words, AER wall is expected to raise economical efficiency because of excellent mechanical stability of Back Supporting Beam.

• Journal of Chest Surgery
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• v.29 no.1
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• pp.107-111
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• 1996

Persistent bronchopleural fistula (BPF) still presents a troublesome therapeutic challenge and demands an aggressive approach when conventional measures fail. A 50-year-old man had a rigtlt pneumonectomy for far-advanced pulmonary tuberculosis with the development of postopneumonectomy empyema and BPF 1 month postoperatively in October 1 81. The condition was managed with BPF closure and the Clagett procedure, which failed with the recurrence of BPF and empyema, followed by a spontaneous open window at about 1 year port:operatively. The BPF, which had been aggravated to a large size, was managed by the closure and obliteration of the empyema cavity using a Pectoralis-skin pedicled flap 13 years postoper atively on Jul, 1994. The BPF was controlled by the procedure, and the patient, with improved respiratory symptom, was discharged 43 days postoperatively. We conclude that the use of myocutaneous flap Is an effective procedure for the closure of a large BPF. The surgical technique of the pedicled flap operation is described and the case is reported.

• Proceedings of the Korean Operations and Management Science Society Conference
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• 2006.05a
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• pp.373-378
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• 2006

Recently the technical advances and complexities have generated much of the difficulties in managing the project resources, for both scheduling and costing to accomplish the project in the most efficient manner. The project manager is frequently required to render judgments concerning the schedule and resource adjustments. This research develops an analytical model for a schedule-cost and risk analysis based on visual PERT/CPM. We used a three-step approach: 1) in the first step, a deterministic PERT/CPM model for the critical path and estimating the project time schedule and related resource planning and we developed a heuristic model for crash and stretch out analysis based upon a time-cost trade-off associated with the crash and stretch out of the project. 2) In second step, we developed web-based risk evaluation model for project analysis. Major technologies used for this step are AHP (analytic hierarchy process, fuzzy-AHP, multi-attribute analysis, stochastic network simulation, and web based decision support system. Also we have developed computer programs and have shown the results of sample runs for an R&D project risk analysis. 3) We developed an optimization model for project resource allocation. We used AHP weighted values and optimization methods. Computer implementation for this model is provided based on GUI-Type objective-oriented programming for the users and provided displays of all the inputs and outputs in the form of GUI-Type. The results of this research will provide the project managers with efficient management tools.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.11 no.8
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• pp.1415-1423
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• 2007

Total efficiency of transmitter system was improved by developing combinational 2-Way Isohybrid for GSM1900 base station in this paper. The size of product was decreased and the characteristics were stabilized. The isohybrid transmitter combiner of chip coupler type and hybrid coupler type were designed and fabricated. Insertion loss for chip coupler type isohybrid was $3.17\;dB{\sim}3.47\;dB$. On the other hand, insertion loss for hybrid coupler type was $3.17\;dB{\sim}3.42\;dB$. Isolations between ANT and port were $24.23\;dB{\sim}29.98\;dB$ in case of chip coupler type Isohybrid and were $26.28\;dB{\sim}36.91\;dB$ in case of hybrid coupler type, respectively.

• Aerospace Engineering and Technology
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• v.13 no.1
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• pp.55-62
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• 2014

FTSR(Flight Termination System Receiver) is a device that receives a ground command signal to abort a flight mission when abnormal conditions occur in the space launch vehicle. The secure tone command message shall consist of a series of 11 character tone pattern. Each character consists of the sum of two tones which taken from a set of 7 tones defined by IRIG(Inter-Range Instrumentation Group) in the audio frequency range. The MHA(Modified High alphabet) command adds a security feature to the secure tone command by using the predefined difference code. In order to check the function and performance of MHA FTSR, which is under development, for KSLV-II, the testbed should have functions of RF signal generation, receiver's output port monitoring, RS-422 communication and test data management. In this paper, we first briefly introduce MHA command and FTSR interface, and then show the LavVIEW based testbed include its H/W configuration, S/W implementation and test results.

• Journal of the Korean Geotechnical Society
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• v.32 no.3
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• pp.15-27
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• 2016

In this study, a series of triaxial compressive strength tests were conducted for basaltic intact rocks sampled in the northeastern onshore and offshore, southeastern offshore and northwestern offshore of Jeju Island. Hoek-Brown constants $m_i$ were estimated from the results of the triaxial compression tests, and the properties of the Hoek-Brown constants $m_i$ were investigated. In addition, the cohesion and internal friction angle, strength parameters of Mohr-Coulomb failure criterion, obtained from the results of the triaxial compression tests were compared and analyzed with those estimated from Hoek-Brown failure criterion, respectively. As results, it was found that the Hoek-Brown constant $m_i$ is deeply related to the internal friction angle. As the internal friction grows, the Hoek-Brown constant $m_i$ increases exponentially. The cohesions estimated from the Hoek-Brown failure criterion, on average, are approximately 24% higher than those obtained from the Mohr-Coulomb failure criterion. The internal friction angles estimated from the Hoek-Brown failure criterion are similar to those obtained from the Mohr-Coulomb failure criterion.

• Strategy21
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• s.37
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• pp.144-176
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• 2015

In September 2013, President Park Geun-hye announced her controversial "Look North" policy, of which the most salient aspect is the "Eurasia Initiative". This comprises various proposals designed to overcome existing constraints by developing new markets and creating new economic partners in continental areas from which South Korea has been alienated since the end of World War II, and this dovetails nicely with China's One Belt, One Road Initiative. The concepts of the "Silk Road Rail Express (SRX)" and the "East Sea Rim Maritime Community (ESRMC)" have also been discussed. SRX is at present a purely symbolic railroad project intended to encourage individual, cultural, trade and diplomatic exchanges. ESRMC is a model for establishing an ad hoc community to promote regional economic cooperation around the East Sea. President Park's Eurasia Initiative will provide South Korean investment for the Northeast to complement Russian plans, like the "Northern Energy Road" being built by Gazprom, and Chinese plans, like the Chang-Ji-Tu Development Plan for the North Korean port of Rajin. China's trade, as well as its energy and food supplies, pass through the Strait of Malacca and the Indian Ocean, and are thus vulnerable to interdiction by India or the US. China is therefore trying to reduce its exposure geopolitical risk by establishing a network of corridors between the Belt and the Road to provide alternative paths. The "China-Pakistan Economic Corridor" and the "China-Myanmar Economic Corridor" provide such connections, and South Korea hopes that SRX and ESRMC can become part of a "China-South Korea Economic Corridor". This concept could do much to revitalize the underdeveloped northern provinces of China and Russia's Far East, not to mention North Korea. By linking up the Trans-Siberian Railway, the Trans-China Railway, the Trans-Mongolian Railway and the Trans-Korean Railway all these Asian countries will be connected to one another, and ultimately to Europe. An interim connection between China and South Korea using a rail-ferry has also been proposed.

• Journal of Biomedical Engineering Research
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• v.24 no.6 s.81
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• pp.523-531
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• 2003

We developed a PC-based 8-channel electrical stimulation system for transcutaneous functional electrical stimulation (FES), and applied it to FES exercise and paraplegic walking. The PC program consists of four parts: a database, a stimulation pattern generator, a stimulus parameter converter, and an exercise program. The stimulation pattern can be arbitrarily generated and edited by using the mouse on the PC screen, and the resulting stimulus parameters arc extracted from the recruitment curves, and transmitted to the 8-channel stimulator through the serial port. The stimulator has nine microprocessors: one master and eight slaves, Each channel is controlled by the slave microprocessor, and is operated independently. Clinical application of the system to a paraplegic patient showed significant increase in the knee extensor torque, the fatigue resistance, and the leg circumference, The patient can now walk about 50 meters for more than 2 minutes.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.4 no.3
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• pp.301-306
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• 2003

We have designed embedded web server system and ported Linux operating system version 2.4.1 at our system. And then We implemented to control and monitor widely separated hardware. Web server is the Boa web server with General Public License. We designed for this system using of Cirrus logic's EP7312 ARM core base processor and connecting input and output device at GPIO port of EP7312. Device driver of General purpose I/O for Linux OS is designed. And then the application program controlling driver is implemented to use of common gate interface C language. User is available to control and monitor at client PC. This method have benefit to reduce the Expenditure of hardware design and development time against PC base system and have various and capacious application against firmware base system.