• 한국정보통신설비학회:학술대회논문집
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• 한국정보통신설비학회 2004년도 하계학술대회
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• pp.386-389
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• 2004

This thesis complemented the weak points that the existing theses did not represented a phase characteristic as the equivalent circuit by applying 4-port simulation to DGS (Defected Ground Structure) characteristic and an equivalent circuit, which are the transmission line structure that has the defect made in the ground surface. We used a distribute device and a lumped device, obtained the equivalent circuit by applying the structure of balun to a discontinuous part. An indicated DGS (Defected Ground structure) is a dumbbells-shaped single defect, we indicated satisfying a magnitude and phase characteristics by applying this equivalent circuit.

• 한국자동차공학회논문집
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• 제9권2호
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• pp.19-27
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• 2001

This paper is the first of 3 companion papers which investigate axial stratification process. In-cylinder fuel behavior has been investigated in the port injected SI engine by visualization for the purpose of understanding stratification. Planar laser light sheet from an Nd:YAG laser has been illuminated through the transparent quartz cylinder of the single cylinder optical engine and the Mie scattered light has been replaced with an air-ethanol mixture to utilize atomized fuel spray for the visualization purposes. This results have been compared with steady flow concentration measurement. For no swirl port, the axial penetration depends on the fuel injection timing. The fuel tends to remain in the upper region of the cylinder far from the spark plug and the distribution is not affected by the injection timing except 90 ATDC.

• 한국시뮬레이션학회논문지
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• 제11권3호
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• pp.1-12
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• 2002

Experimental design in simulation provides an efficient way of economizing simulation runs since a considerable number of simulation runs that originally were planned can be reduced by this approach. This experimental design method is an active area of research together with the output analysis and so no single panacea seems to exist so far. Thus, selection of techniques of experimental design and output analysis more likely depends upon the objective of simulation analysis, budget constraint and sometimes the analyst's subjective judgment. This paper attempts to describe an experimental design methodology for port investment analysis using a case study in a bulk terminal in Korea. Detailed display will be focused on simulation period, warm-up period, the number of replications needed in production runs after brief explanation on the system configuration.

• International Journal of Control, Automation, and Systems
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• 제6권2호
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• pp.278-281
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• 2008

Linear motor (LM) based shuttle cars will play an important role in the future transportation systems of marine terminals to cope with increasing container flows. These systems are known as agile port terminals because of their significant advantages. However, routing for multiple shuttle cars is still an open issue. We present a network model of a container yard and propose constrained dynamic programming (DP) for its routing strategy with collision avoidance. The algorithm is a modified version of typical DP which is used to find an optimal path for a single traveler. We evaluate the new algorithm through simulation results for three shuttle cars in a mesh-type container yard.

• 한국항만학회지
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• 제8권1호
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• pp.65-74
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• 1994

There are some turn maneuvers, such as hard Round Turn, Turning Short Round, Williamson Turn and Single Turn, of effectively returning a ship back close to the original track in case of emergency situations of man-overboard and intentional delay of port entrance time, and so forth. But the author developed the new turn maneuvers of Double 30 (woo) Turn originally by means of simulation experiments of Full-Mission Shiphandling Simulator. The conclusions of this study are as follows: 1) By comparison of existing Williamson Turn and Turning Short Round this Double 30(woo) Turn is all-weather multipurpose turn maneuvers in some respects, 2) According to simulation experiments this Double 30 (woo) Turn saved approximately 20-35% of total turning time to the original position and reduced maximum advances by 8-10% approximately in comparison to that of Williamson Turn, 3) Except for emergency men-overboard the Reverse Williamson Turn was proposed as a new reverse maneuver of returning a ship back to the original track.

• 전자공학회논문지D
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• 제34D권10호
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• pp.14-23
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• 1997

An MMIC downconverting mixer for cellular phone application has been successfully developed using an MMIC process including $1 \mu\textrm{m}$ ion implanted gaAs MESFET and passive lumped elements consisting of spiral inductor, $Si_3N_4$ MIM capacitor and NiCr resistor. The configuration of the mixer presented in this paper is single-ended dual-gate FET mixer with common-source self-bias circuits for single power supply operation. The dimension of the fabricated circuit is $1.4 mm \times 1.03 mm $ including all input matching circuits and a mixing circuit. The conversion gian and noise figure of the mixer at LO powr of 0 dBm are 5.5dB and 19dB, respectively. The two-tone IM3 characteristics are also measured, showing -60dBc at RF power of -30dBm. Allisolations between each port show better than 20dB.

• Journal of Gastric Cancer
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• 제18권2호
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• pp.172-181
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• 2018

Purpose: This study aimed to evaluate the surgical outcomes and investigate the feasibility of reduced-port laparoscopic gastrectomy using learning curve analysis in a small-volume center. Materials and Methods: We reviewed 269 patients who underwent laparoscopic distal gastrectomy (LDG) for gastric carcinoma between 2012 and 2017. Among them, 159 patients underwent reduced-port laparoscopic gastrectomy. The cumulative sum technique was used for quantitative assessment of the learning curve. Results: There were no statistically significant differences in the baseline characteristics of patients who underwent conventional and reduced-port LDG, and the operative time did not significantly differ between the groups. However, the amount of intraoperative bleeding was significantly lower in the reduced-port laparoscopic gastrectomy group (56.3 vs. 48.2 mL; P<0.001). There were no significant differences between the groups in terms of the first flatus time or length of hospital stay. Neither the incidence nor the severity of the complications significantly differed between the groups. The slope of the cumulative sum curve indicates the trend of learning performance. After 33 operations, the slope gently stabilized, which was regarded as the breakpoint of the learning curve. Conclusions: The surgical outcomes of reduced-port laparoscopic gastrectomy were comparable to those of conventional laparoscopic gastrectomy, suggesting that transition from conventional to reduced-port laparoscopic gastrectomy is feasible and safe, with a relatively short learning curve, in a small-volume center.

• 한국항만경제학회지
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• 제34권4호
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• pp.191-208
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• 2018

본 논문은 부산항 경쟁력 강화를 위한 운영체제 개선방안 도출을 위해 운영사 통합 측면에 집중하여 그 대안을 모색하였다. 그 결과 통합에 따른 가치평가 기준과 통합시기에 대한 로드맵 마련, BPA의 통합 참여여부, 범위와 역할 설정 및 북항 신항 운영사 통합과정의 분리와 연계 추진을 그 대안으로 제시하였다. 구체적으로 살펴보면 다음과 같다. 첫째, 통합에 따른 가치평가 기준은 국제기준을 적용하되, 참여기업의 재무상황, 영업실적, 수익성과 같은 양적 요소와 경영능력, 기술력, 노사관계 등과 같은 질적 요소를 동시에 고려해야 한다. 둘째, 통합시기는 북항과 신항을 분리하여 추진할 수 있지만 단기적으로 북항 운영사 통합을 우선적으로 고려하되 신항 2-4, 2-5, 2-6단계 개장 시기와 연계하여 추진하고 신항 운영사 통합은 비교적 장기적 관점을 가지고 추진할 수 있는 로드맵을 제시하는 것이 바람직하다. 셋째, BPA의 통합운영사 참여는 각 터미널간 정책적 조정자로서 공공성과 K-GTO(Korean global terminal operator) 육성을 통한 해외사업 진출이라는 수익성 추구라는 2가지 측면에서 함께 고려하되, 출자지분의 제한과 국적, 외국적 운영사 구분에 구애받지 않고 터미널 운영사업의 경험과 기술을 최대한 확보할 수 있도록 참여범위와 역할을 제시하였다. 넷째, 북항 신항 운영사 추진방안으로 북항 운영사의 단일법인 형태로의 물리적 통합이 어렵기 때문에, 초기에는 특수목적법인(Specail Purpose Company, SPC)을 설립하여 통합운영의 효과를 기대하고 참여 운영사들이 국가나 부산항만공사와 체결한 부두임대 계약기간의 종료시기 등을 감안하여 지주회사 형태로 전환한 후 최종적으로는 단일법인으로 합병해 나가는 방안을 제시하였다. 끝으로 본 연구에서 제시한 운영사 통합 추진이 부산항 운영상의 문제를 모두 해결할 수 있는 대안이 될 수는 없지만 최소한 근본적인 문제 해결을 위한 접근으로는 평가될 수 있으며, 물리적 통합에 집착하지 않고 현실적으로 실현가능한 통합방안을 모색하는 것이 필요하다고 사료된다.

• 한국항해항만학회지
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• 제48권3호
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• pp.232-238
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• 2024

본 연구는 현재 감천항에 입항하는 선박교통 특성을 반영하여 감천항 도등의 효용성을 검토하였다. 감천항 도등은 1996년 4,000TEU 컨테이너선 출입항을 위해 감천항 항로표지 보완 기본설계과정에서 제안되어 설치되었다. 이후 부산지방해양수산청의 감천항 정온도 향상을 위한 기존 외곽 시설 재배치 검토 연구를 통해 50,000DWT급 일반 화물선 입항 대응 및 한진 부두의 크레인 높이를 반영한 도등으로 개선되었다. 그러나 현재 감천항의 해상교통 특성을 보면 해상교통 혼잡도도 원활하고 대형선박 보다는 10,000톤 이하의 중소형 선박 비중이 높아 대형선박 입항을 대응하기 위해 개선된 도등의 효율성은 감소되었다고 볼 수 있다. 그러나 입항선박의 규모에 따른 변화 추이를 보면 30,000톤 이상선박의 입항비율의 연평균증가율(CAGR)이 8.45%로 증가되고 있어 향후 대형선박의 입항비중 증가에 대한 대비를 위해서는 감천항 도등을 필수 등화로 유지하는 것이 필요하다. 따라서 도등을 철거할 경우 감천항 항로의 협소한 공간 특성상 입출항 선박이 조우하는 경우에는 충돌의 위험이 증가하여 항해자에게 큰 부담이 될 수 있기 때문에 도등의 기능은 유지하는 대신 전도등을 이전설치 하여 유지보수에 대한 부담을 경감시키는 방법과 도등의 기능 대신 지향등을 설치하는 방법을 고려해 볼 수 있다. 지향등 설치 시 인근 부산북항에 설치된 Single Sector Lights가 명확한 중시선을 제공하지 못하여 지점에 따라 명확한 구분이 어려움에 따라 이용자 만족도가 떨어지는 부분을 개선할 수 있는 Double Sector Lights를 설치를 고려해볼 수 있다.

• Journal of electromagnetic engineering and science
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• 제3권2호
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• pp.86-90
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• 2003

A flat conversion loss in microwave mixer is hard to achieve if integrating with an image rejection filter(IRF). This is due to the change of termination condition with respect to the LO and IF frequency at RF port where the filter has 50 ohm termination property only in the RF band. This paper describes a flatness maintenance in the down mixer concerning a diode matching condition as well as an electrical length of embedding line at RF port. The implemented single balance diode mixer is suitable for a 23 ㎓ European Terrestrial Radio. RF, LO and fixed IF frequency chosen in this paper are 21.2∼22.4 ㎓, 22.4∼23.6 ㎓ and 1.2 ㎓, respectively. The measured results show a conversion loss of 8.5 ㏈, flatness of 1.2 ㏈ p-p, input P1㏈ of 7㏈m, IIP3 of 15.42 ㏈m with nominal LO power level of 10㏈m. The return loss of RF and LO port are less than - 15 ㏈ and - 12 ㏈, respectively and IF port is less than - 6 ㏈. LO/RF and LO/IF isolation are 18 ㏈ and 50 ㏈, respectively. This approach would be a helpful reference for designing up/down converter possessing a filtering element.