• The Transactions of the Korean Institute of Electrical Engineers D
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• v.53 no.5
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• pp.345-352
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• 2004

Currently, high data rate PLC(Power Line Communications), up to 100 Mbps, which use frequency bandwidth between 2 MHz and 30 MHz is investigated very hard, and commercial PLC modem for low voltage powerline network (indoor) is coming soon into communication market. For the purpose of developing a fit communication system which has little distortion of signal and attenuation, it is surely necessary to know about channel environments of powerline. Especially, the impedance measurement of the powerline and impedance matching are very important. As is known, since medium-voltage powerline (22.9 ㎸) is still working, it is not so simple to measure the powerline impedance. In our study, a portable impedance measurement equipment is developed. It consists of coupling capacitor, a drain coil and impedance matching transformer. The equipment is easily connected to medium voltage line and impedance of power line is measured using a network analyzer. Also, measurement results are used for impedance matching of PLC signal. In fact, matching transformer with several different impedances are used. The matching transformer is connected between coupling capacitor and signal port. In this paper, the developed portable impedance measurement equipment and impedance measurement results are presented. Also impedance matching technique using matching transformers will be explained. We showed the result of the improved performance by the impedance matching.

• Journal of Chest Surgery
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• v.55 no.1
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• pp.81-84
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• 2022

Esophagectomy and esophageal reconstruction are commonly chosen as surgical options for esophageal cancer. However, prolonged untreated chyle leakage is associated with a poor prognosis. We report the case of a patient with refractory chylous ascites. To limit the ongoing fluid loss, we utilized the chylous ascites as an additional fluid source in a renal replacement therapy system. A continuous renal replacement therapy (CRRT) drainage system was modified to drain both the chylous ascites and venous blood. The ascites drainage rate was determined empirically and regulated by a dial-flow extension set. The CRRT mode was set to continuous venovenous hemodiafiltration and maintained for 7 days. After the patient was weaned from CRRT, ascites did not reaccumulate, and the patient's general condition improved dramatically. No infections related to the system occurred. This procedure temporarily alleviates symptoms and provides more time for alternative treatment strategies.

• Journal of Drive and Control
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• v.20 no.4
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• pp.9-16
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• 2023

This paper analyzed a drainage tower used to drain water in flooded areas. Multi-body dynamics simulation was used to analyze the dynamic behavior of the drainage tower. Structural analysis, flexible-body dynamic analysis, and rigid body dynamic analysis were done to study the maximum Von-Mises stress of the drainage tower. The results showed that the maximum Von-Mises stress occurs at the turn table, and it decreases when the angle of the boom is increased. Also, the rate of the change of angle affects the maximum stress so that the maximum stress changes more when the angular velocity of the boom increases. Based on the rigid body dynamic analysis and the theoretical analysis results, the centrifugal force from the angular velocity makes the difference in the maximum stress at the turn table because of the difference in their direction. Consequently, it was concluded that the centrifugal force should be considered when designing construction machinerythat can rotate.

• Journal of the Korean Geosynthetics Society
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• v.13 no.4
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• pp.33-43
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• 2014

Recently, the case to construct the structure on the soft clayey ground has increased and in order to the reduction of the cost of construction and maintenance on the social infrastructure facilities we have been trying to improve the soft clayey ground using the existing methods such as the pre-loading method and the vertical drain method. Like this, when various ground improvement methods are applied on the soft clayey ground, a long-term consolidation settlement will be key issue due to low permeability coefficient of cohesive soil. According to existing research results that relate to the consolidation settlement, the loading periods for existing the standard consolidation test (Oedometer test) to obtain the consolidation parameters are needed for minimum ten days or more. Therefore, in this study, the standard consolidation test (24 hours step-loading) and constant strain rate consolidation test changed by strain rate was performed using the remolded marine clay on Gwangyang bay composed of a soft clayey ground of the south-west coast. From the laboratory test results, the characteristics of compression, strain-effective stress relations by constant strain rate and the variation characteristic of the pore water pressure by different of loading speed and the relation between consolidation parameters and constant strain rate are compared and analyzed.

• New Physics: Sae Mulli
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• v.68 no.11
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• pp.1192-1195
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• 2018

We studied the electrical properties of organic thin-film transistors (OTFTs) fabricated at different deposition rates by measuring the field-effect mobility and the threshold voltages. As the active layer, pentacene thin film with a thickness of 50 nm was deposited at a rate of $0.05{\AA}/s$ to $1.14{\AA}/s$. The thickness of the drain-source gold electrode was 50 nm. The mobility was $1.9{\times}10^{-1}cm^2/V{\cdot}s$ at a deposition rate of $0.05{\AA}/s$, the mobility increased to $5.2{\times}10^{-1}cm^2/V{\cdot}s$ when the deposition rate was increased to $0.4{\AA}/s$, and then the mobility decreased to $6.5{\times}10^{-1}cm^2/V{\cdot}s$ when the deposition rate decreased to $1.14{\AA}/s$. Thus, the mobility of pentacene OTFTs was observed to depend on the thermal deposition rate.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.7 no.2
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• pp.263-268
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• 2003

In this paper, we have investigated double gate (DG) MOSFET structure, which has main gate (NG) and two side gates (SG). We know that optimum side gate voltage for each side gate length is about 3V in the main gate 50nm. Also, we know that optimum side gate length for each for main gate length is about 70nm. DG MOSFET shows a small threshold voltage roll-off. From the I-V characteristics, we obtained IDsat=550$mutextrm{A}$/${\mu}{\textrm}{m}$ at VMG=VDS=1.5V and VSG=3.0V for DG MOSFET with the main gate length of 50nm and the side gate length of 70nm. The subthreshold slope is 86.2㎷/decade, transconductance is 114$mutextrm{A}$/${\mu}{\textrm}{m}$ and DIBL (Drain Induced Barrier Lowering) is 43.37㎷. Then, we have investigated the advantage of this structure for the application to multi-input NAND gate logic. Then, we have obtained very high cut-off frequency of 41.4GHz in the DG MOSFET.

• Journal of Korean Society of Water and Wastewater
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• v.31 no.6
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• pp.567-575
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• 2017

It is not cost effective to raise the density of catch basins in preparation for heavy rainfall in terms of construction and maintenance. Our researchers have developed the new catch basin for increasing interception capacity of runoff with internal filtration structure. To compare interception capacity of an existing catch basin with the invented catch basin, a hydraulic experiment device with 4% of road gradients and 0.2% of road gradients was constructed. For runoff conditions of 4.4 l/s, 6.7 l/s and 10.4 l/s, capability of runoff and separation capability of debris (sand and leaves) were evaluated. As the main experimental results, the effectiveness of the developed catch basin has been verified with an increase in interception rate of approximately 22% for the runoff of 6.7 l/s as heavy rainfall. However, the results of invented catch basin showed only 4.5% of settlement rate of debris regarding sand. Therefore, the authors proposed an improved tilted screen structure additionally. After reviewing the performance of improved catch basin, application of the invented catch basin is expected to drain runoff effectively when it is applied to the faulty road drainage section.

• Archives of Plastic Surgery
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• v.36 no.4
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• pp.393-396
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• 2009

Purpose: Low - molecular - weight dextran is one of the most frequently used antithrombotic agents in microvascular surgery, but there is controversy if it has the real benefit in the clinical aspects. The purpose of this study was to evaluate the effect associated with postoperative use of low - molecular - weight dextran in breast reconstruction by free TRAM flap patients. Methods: From January 2002 to October 2008, we reconstructed 88 cases of postmastectomy deformity using the free TRAM flap. The 88 cases were divided into two groups : a group with no use of dextran(66 patients, control group, Group A) and a postoperative low - molecular weight dextran loaded group(22 patients, Group B). We assessed number of flap survival, rate of complication like hematoma or seroma, total amount of drainage from operative wound, duration of drainage, and amount of transfusion in each group. Results: There was no total flap loss and every flap was survived. Total amount of drainage for post - operative 5 days were 857 ml in group A and 1101 ml in group B. Drain was kept for average of 7.3 days in group A and 8.7 days in group B. Packed red cell transfusions were made in average of 3.3 units for group A and 3.0 units for group B. Group B showed significantly higher values in former 2 comparative parameters than group A. Conclusion: There was no definitive advantage of anticoagulants in elective free - flap surgery in terms of success rate. However, groups with using anticoagulants had the increased bleeding tendency in immediate postoperative period. The routine use of anticoagulants in elective free - flap surgery should be reconsidered with postoperatively less bleeding and early recovery.

• Journal of Minimally Invasive Surgery
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• v.21 no.4
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• pp.148-153
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• 2018

Purpose: Single incision laparoscopic appendectomy (SILA) is a widely used surgical procedure for treatment of appendicitis with better cosmesis. However, many surgeons generally tend to choose conventional multiport laparoscopic appendectomy regarding with complicated appendicitis. The aim of this study is to demonstrate the safety and feasibility of SILA for treatment of complicated appendicitis by comparison with 3-ports conventional laparoscopic appendectomy (CLA). Methods: Retrospective chart review of patients diagnosed appendicitis at single hospital during January 2015 to May 2017 collected 500 patients. Among 134 patients with complicated appendicitis, we compared outcomes for 29 patients who got SILA and 105 patients who got CLA. Results: 179 and 321 patients were treated by SILA and CLA, respectively. 134 (26.8%) patients were treated for complicated appendicitis, 29 patients by SILA and 105 patients by CLA, respectively. There was no case converted to open or added additional trocar in both groups. There were no differences in demographics with regard to age, sex, body mass index (BMI), and American society of anesthesiologists (ASA) scores. There was no difference in mean operating time ($58.97{\pm}18.53$ (SILA) vs. $57.57{\pm}21.48$ (CLA), p=0.751). The drain insertion rate (6.9% vs 37.1%, p=0.001) and the length of hospital stay ($2.76{\pm}1.41$ vs. $3.97{\pm}2.97$, p=0.035) were lower in SILA group with significance. There was no significant difference in the rate of surgical site infection (6.9% vs. 6.7%, p=1.000). Conclusion: This study demonstrates that SILA is a feasible and safe procedure for treatment of complicated appendicitis.

• Archives of Plastic Surgery
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• v.48 no.2
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• pp.165-174
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• 2021

Background In recent years, implant-based breast reconstruction has been performed because of its simplicity, short operation time, and rapid recovery of patients. Several studies have reported treatment methods for implant surgery-related infection, which is a serious complication. The aim of this study was to introduce our strategy for salvaging infected implants and to evaluate its effectiveness. Methods The authors performed a retrospective study of 145 cases from 132 patients who underwent implant-based breast reconstruction from January 2012 to December 2018. Empirical antibiotics were immediately administered to patients with suspected infections. The patients then underwent salvage treatment including appropriate antibiotics, ultrasonography-guided aspiration, debridement, antibiotic lavage, and implant exchange through a multidisciplinary approach. Patient demographics, operative data, duration until drain removal, adjuvant treatment, and complications were analyzed. Results The total infection rate was 5.5% (8/145). A longer indwelling catheter period and adjuvant treatment were significantly associated with infection. The salvage treatment showed a success rate of 87.5% (7/8). Seven patients who received early aggressive salvage treatment recovered from infection. One patient with methicillin-resistant Staphylococcus aureus, who received salvage treatment 11 days after symptom onset, did not respond to drainage and antibiotic treatment. That patient subsequently underwent explantation. Conclusions In implant-based breast reconstruction, prevention of infection is of the utmost importance. However, if an infection is suspected, proactive empirical antibiotic therapy and collaboration with the necessary departments are required. Through a multidisciplinary approach and proactive early management, swift and appropriate salvage should be performed.