• Proceedings of the KIEE Conference
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• 2006.10a
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• pp.137-138
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• 2006

In this paper, we study the algorithm for the multiport measurements using the 2port VNA(Vector network Analyzer). We explain the conversion algorithm which the open impedance to the matched impedance(50 ohm), and then we apply this algorithm to the 4 port VNA measurement. Finally, we discuss the reliability of this algorithm.

• Journal of Yeungnam Medical Science
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• v.35 no.2
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• pp.150-155
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• 2018

Recently, an increasing interest in less invasive surgery has led to the advent of laparoendoscopic single-site surgery (LESS) and natural orifice transluminal endoscopic surgery (NOTES). LESS and NOTES could be technically challenging, but available literature has demonstrated the feasibility and safety of LESS for benign gynecologic diseases. However, the evidence is not strong enough to recommend the use of LESS over that of conventional multiport laparoscopic surgery (MLS). As per the results of the most recently published meta-analysis, the majority of surgical outcomes are equivalent between LESS and MLS, except for the longer operative time in LESS for both adnexal surgery and hysterectomy. Although an increasing number of studies have reported on robotic LESS, NOTES, and LESS for gynecologic malignancy, definite conclusions have not been drawn owing to the lack of sufficient information.

• Water Engineering Research
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• v.3 no.2
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• pp.93-111
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• 2002

In this paper, mixing characteristics and dilution of the merging buoyant discharges from array of multiple jets has been extensively studied in the hydraulic model experiments. New equations for dilution, which include the merging effects correctly, were derived. Experiments were constructed in a 20-m long, 4.9-m wide and 0.6-m deep flume, and the model diffuser was manufactured to indicate the typical characteristics of the existing ocean wastewater outfall in South Korea. Buoyant discharge from the diffuser was reproduced using heated water. Water temperature was measured using CC-Type thermocouple sensors, which were connected to a 40-channel data logger. Experimental results show that merging between ports in a particular riser is dependent upon the discharge densimetric Froude number, whereas merging between two ports which are facing each other at 90$\circ$ at the adjacent risers is dependent upon the discharge densimetric Froude number and distance from the port and port spacing. Centerline dilution increase with distance from the port outlet until two plumes has merged. However, after merging occurs, increase of the centerline dilution almost stops. Further distance from the position where merging occurs, centerline dilution increases again.

• Journal of electromagnetic engineering and science
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• v.16 no.4
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• pp.199-205
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• 2016

We present a novel schematic using a 3-dB coupler to transmit radiofrequency (RF) power to two receivers selectively. Whereas previous multiple receiver supporting schemes used hardware-switched methods, our scheme uses a soft power-allocating method, which has the advantage of variable power allocation in real time to each receiver. Using our scheme, we can split the charging area and focus the RF power on the targeted areas. We present our soft power-allocating method in three main points. First, we propose a new power distribution hardware structure using a FPGA (field-programmable gate array) and a 3-dB coupler. It can reconfigure the transmitting power to two receivers selectively using accurate FPGA-controlled signals with the aid of software. Second, we propose a power control method in our platform. We can variably control the total power of transmitter using the DC bias of the drain input of the amplifier. Third, we provide the possibility of expansion in multiple systems by extending these two wireless power transfer systems. We believe that this method is a new approach to controlling power amplifier output softly to support multiple receivers.

• Ocean and Polar Research
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• v.22 no.2
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• pp.69-80
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• 2000

A 3-D particle tracking model with normalized characteristic equations has been developed to predict the variation of near-field mixing characteristics and the far-field transport of the effluent plumes discharged from sea outfalls. The model was applied to the case study on the Masan sea outfall plumes discharged through a submerged multiport-diffuser. Numerical simulations of the effluent transport for 15 days which cover neap and spring tidal cycles in Masan Bay were conducted using fall velocities of the solid wastes and the initial plume characteristics obtained from normalized near-field characteristic equations. The results showed that time variations in near-field minimum dilutions with tidal ambient flow conditions are about $45{\sim}49$. Most of the heavy particles in the effluent plumes were settled and deposited in the vicinity of the outfalls immediately, and the finer particles were transported eastwards 3 km away from the outfalls for 15 days. A similar depositional trend of contaminated sediment was also found during a recent field survey.

• Proceedings of the KIEE Conference
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• 1997.07c
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• pp.878-879
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• 1997

본 논문에서는 전자기 과도현상 해석을 위한 다단자 회로망 등가표현법을 제안한다. 이 방법은 M개의 경계모선을 가진 축약대상 계통의 과도특성을 시간 영역에서 분석하며 이를 이용해 M 개의 노톤형 이산시간 등가 어드미턴스 필터꼴의 등가시스템을 구현한다. 이 때 각각의 등가 어드미턴스 필터 모델들은 해당 경계모선에서의 구동점 어드미턴스 특성을 나타내는 부분과 나머지 M-1 개의 등가 종속전류원으로 구성된다. 또한 이 등가 종속전류원들은 각 경계모선을 연결하는 분포정수 회로요소들로 인한 시지연 효과를 명확하게 반영할 수 있는 구조를 갖는다. 완성된 M 단자쌍 모델을 해석대상 시스템에 대한 이산시간 표현형과 쉽게 결합하여 원하는 전자기 과도현상 모의해석을 수행할 수 있다. 축약대상 시스템과 2 개의 경계모선을 통해 연결된 시험계통을 대상으로 모선지락 사고시 과전압과 스위칭 써지를 모의해석한 결과 제안하는 방법이 타당함을 확인할 수 있었다.

• Journal of Gastric Cancer
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• v.17 no.3
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• pp.193-203
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• 2017

The implementation of national cancer screening has increased the detection rates of early gastric cancer (EGC) in Korea. Since the successful introduction of laparoscopic gastrectomy for gastric cancer in the early 1990s, this technique has demonstrated improved short-term outcomes without compromising long-term oncologic results. It is associated with reduced pain, shorter hospitalization, reduced morbidity rates, better cosmetic outcomes, and equivalent mortality rates as those for open surgery. Laparoscopic gastrectomy improves patients' quality of life (QOL) and provides favorable prognosis. Single-incision laparoscopic gastrectomy (SILG) is one extremely minimally invasive method, theoretically offering improved cosmetic results, less postoperative pain, and earlier recovery after surgery than conventional multiport laparoscopic gastrectomy. In this context, SILG is thought to be an optimal method to promote and maximize patients' QOL in the acute postoperative phase. However, the technical difficulties of this procedure have limited its use. Since the first report describing single-incision distal gastrectomy in 2011, only 16 studies to date have evaluated SILG. Most of these studies have focused on the technical feasibility and safety of SILG because its long-term outcomes have not been reported. This article reviews the advantages and limitations of SILG.

• Proceedings of the Optical Society of Korea Conference
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• 2000.08a
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• pp.60-61
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• 2000

표면 형상을 측정하는 방법은 샘플표면의 평평도, 곡률, 거칠기, 깊이 측정등의 수많은 상업적 응용을 위해 광범위하게 개발되어왔다. 이중에서도 특히 간섭현상을 이용한 광 표면 프로파일러는 표면의 3차원 구조를 측정하는데 있어서 subangstrom의 매우 높은 깊이 분해능을 가지므로 샘플 표면의 정밀 진단에 많이 사용되어 왔다. [1,2] 광 간섭 현미경은 기본적으로 광위상 변화를 검출하여 그것을 표면구조변화로 바꾸어주는 역할을 한다. 그러나 광위상 변화는 샘플 표면의 구조뿐만 아니라 물질 변화와 박막두께 변화에도 민감하므로 순수한 표면구조측정은 샘플이 단일물질인 경우에만 달성된다는 문제점이 있다. 따라서 이러한 광위상 측정과 관련된 ambiguity를 해결하기 위해서는 일반적인 광 간섭 현미경에서 얻어지는 위상데이터와 더불어 물질변화를 분석할 수 있는 다른 추가적인 데이터가 필요하다. 이러한 필요성 때문에 우리는 광위상 뿐만 아니라 반사율 분포도 동시에 측정할 수 있는 새로운 방식의 다출력단 호모다인 간섭계(Homodyne I/Q Interferometer; HIQI)를 구성하였으며[3], 그 실험장치도는 [Fig. 1]과 같다. HIQI는 in-phase and quadrature 검출방식에 기반을 두며, 이 검출방식은 PBS에서 반사되는 빛살과 투과되는 빛살 사이의 위상차가 $\pi$/4라는 실험결과로부터 달성된다. HIQI는 샘플 표면의 3차원 구조 뿐만 아니라 광학적 특성의 2차원 분포도 동시에 얻을 수 있다. (중략)

• Archives of Plastic Surgery
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• v.48 no.6
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• pp.577-582
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• 2021

Robot-assisted surgery is evolving to incorporate a higher number of minimally invasive techniques. There is a growing interest in robotic breast reconstruction that uses autologous tissue. Since a traditional latissimus dorsi (LD) flap leads to a long donor scar, which can be an unpleasant burden to patients, there have been many attempts to decrease the scar length using minimally invasive approaches. This study presents the case of a patient who underwent a robot-assisted nipple-sparing mastectomy followed by immediate breast reconstruction with an LD flap using a single-port robotic surgery system. With the assistance of a single-port robot, a simple docking process using a short and less visible incision is possible. Compared to multiport surgery systems, single-port robots can reduce the possibility of collision between robotic arms and provide a clear view of the medial border of the LD where the curvature of the back restricts the visual field. We recommend the use of single-port robots as a minimally invasive approach for harvesting LD flaps.

• Journal of Gastric Cancer
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• v.12 no.3
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• pp.173-178
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• 2012

Purpose: To report the initial clinical experience with single-incision laparoscopic gastric wedge resection for submucosal tumors. Materials and Methods: The medical records of 10 patients who underwent single-incision laparoscopic gastric wedge resection between July 2009 and March 2011 were reviewed retrospectively. The demographic data, clinicopathologic and surgical outcomes were assessed. Results: The mean tumor size was 2.5 cm (range, 1.2~5.0 cm), and the tumors were mostly located on the anterior wall (4/10) or along the greater curvature (4/10), of the stomach. Nine of ten procedures were performed successfully, without the use of additional trocars, or conversion to laparotomy. One patient underwent conversion to multiport laparoscopic surgery, to get simultaneous cholecystectomy safely. The mean operating time was 66.5 minutes (range, 24~132 minutes), and the mean postoperative hospital stay was 5 days (range, 4~7 days). No serious perioperative complications were observed. Of the 10 submucosal tumors, the final pathologic report revealed 5 gastrointestinal stromal tumors, 4 schwannomas, and 1 heterotopic pancreas. Conclusions: Single-incision laparoscopic gastric wedge resection for gastric submucosal tumors is feasible and safe, when performed by experienced laparoscopic surgeons. This technique provides favorable cosmetic results, and also short hospital stay and low morbidity, in carefully selected candidates.