• 대한전자공학회논문지
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• 제17권5호
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• pp.48-55
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• 1980

고스트제거용 안테나의 구함을 목적으로 동일한 복사패턴의 안테나 2개를 일정한 간격으로 나란히 설치하고 정면방향이외에서 도래하는 방해파에 대해서 두 안테나의 수신전계의 합 출력과 착출력사이에 radian의 위상차가 있는 것에 착목하여 착 신호의 출력을 + 또는 radian 만큼 이상하고 그 진폭을 조정한 다음 합신호와 합성함으로서 종합출력에 나오는 방해파를 제어할 수 있음을 알고 이에 대한 회로를 시작하여 이 회로의 동작으로 방해파가 약 20dB 감소되는 결과를 얻었다.

• Preventive Nutrition and Food Science
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• 제1권1호
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• pp.41-45
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• 1996

This study was conducted to develop the fermentation kinetic model for the prediction of acidity and pH changes in Kimchi as a function of fermentation temperatures. The fitness of the model was evaluated using traditional two-step method and an alternative non-linear regression method. The changes in acidity and pH during fermentation followed the pattern of the first order reaction of a two-step method. As the fermentation temperature increased from 4$^{\circ}C$ to 28, the reaction rates of acidity and pH were increased 8.4 and 7.6 times, respectively. The activation energies of acidity and pH were 16.125 and 16.003kcal/mole. The average activation energies of acidity and pH using a non-linear method were 16.006 by the first order and 15.813 kcal/mole by the zero order, respectively. The non-linear procedure had better fitting 개 experimental data of the acidity and pH than two-step method. The shelf-lives based on the time to reach the 1.0% of acidity were 33.1day at 4$^{\circ}C$ and 2.8 day 28$^{\circ}C$.

• 한국광학회지
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• 제14권3호
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• pp.244-248
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• 2003

공초점 렌즈의 조합으로 사용되는 두 렌즈의 초점거리의 비율에 해당하는 비율 만큼 입사되는 광의 입사각을 줄일 수 있다. 이 결과로 CCD상의 간섭 패턴의 공간 주파수가 낮아진다. 따라서 CCD의 구성 화소들의 간격에 의해 한정되는 기록 가능한 공간 주파수 보다 높은 공간 주파수의 간섭 패턴을 기록할 수 있어 보다 큰 물체의 간섭 패턴을 기록할 수 있다. 또한 이러한 광학계로 기록한 간섭 패턴의 수치적 재생(Numerical Reconstrction) 결과에서는 0-차 회절광의 면적이 초점거리 비율의 역수의 제곱에 해당하는 만큼 축소되는 장점이 있다.

• 한국분무공학회지
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• 제28권2호
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• pp.62-67
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• 2023

Recently, the global automobile industry is aiming for a transition from internal combustion locomotives to zero-emission vehicles. Electric vehicles powered by battery energy can operate at peak performance and improve fuel economy by applying multiple motors or multi-speed transmissions. In order to design a two-speed transmission, it is necessary to evaluate and analyze the application system and performance of electric vehicles. In this study, control performance optimization of a twostage battery electric vehicle equipped with an AMT-based automatic transmission was performed and performance according to control pattern changes was analyzed. In order to improve the operating efficiency of the motor, the shift control that sets the optimal operating point according to the vehicle speed and required torque was derived from the motor efficiency map. The performance of battery energy consumption and transmission loss energy according to the hysteresis interval was analyzed and optimized. The hysteresis interval applied to the optimal shift map acted as a factor in reducing the frequency and loss of shifts. It has been shown that keeping the hysteresis interval at about 4 km/h can reduce energy consumption while reducing the number of shifts.

• Steel and Composite Structures
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• 제47권5호
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• pp.633-644
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• 2023

Taking a look at the previously published papers, it is revealed that there is a porosity index limitation (around 0.35) for the mechanical behavior analysis of the functionally graded porous (FGP) structures. Over mentioned magnitude of the porosity index, the elastic modulus falls below zero for some parts of the structure thickness. Therefore, the current paper is presented to analyze the vibrational behavior of the FGP Timoshenko beams (FGPTBs) using a novel refined formulation regardless of the porosity index magnitude. The silica aerogel foundation and various hydrothermal loadings are assumed as the source of external forces. To obtain the FGPTB's properties, the power law is hired, and employing Hamilton's principle in conjunction with Navier's solution method, the governing equations are extracted and solved. In the end, the impact of the various variables as different beam materials, elastic foundation parameters, and porosity index is captured and displayed. It is revealed that changing hygrothermal loading from non-linear toward uniform configuration results in non-dimensional frequency and stiffness pushing up. Also, Al - Al2O3 as the material composition of the beam and the porosity presence with the O pattern, provide more rigidity in comparison with using other materials and other types of porosity dispersion. The presented computational model in this paper hopes to help add more accuracy to the structures' analysis in high-tech industries.

• 패션비즈니스
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• 제27권5호
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• pp.108-120
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• 2023

Recently, interest in eco-friendliness and sustainability has been increasing due to the rapid progress of fast fashion and the crisis of sudden environmental changes after COVID-19. This study aims to develop upcycling textiles and express product design using digital 3D to realize a sustainable fashion industry and present environmental aspects, diversity, creativity, and new directions in fashion industry design. The research method is to develop and pattern upcycling textile designs by applying weaving techniques with waste materials. It uses the developed upcycling textile design in digital 3D to incorporate it into clothing fashion and shows the utility and practicality of upcycling textile design. As a result of the study, the appearance is realistic when outputting DTP of upcycling textile design. It endures without loosening or tearing, making it a durable and creatively expressive fashion item. Texpro 3D mapping reduces the time and cost of making actual sample fabric. Upcycling textile design and 3D CLO virtual clothing are combined to produce actual clothing samples, resulting in zero waste reduction due to cutting and sewing. This study anticipates actively and continuously advancing the development of upcycling textile design and digital 3D in terms of ethics and the environment.

• Wind and Structures
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• 제39권1호
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• pp.31-45
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• 2024

This paper examines the flow characteristics around an inclined prism with a U-shaped cross-section ("U-profile") and investigates the connection between the flow and flow-induced vibrations. The study employs a combined approach that involves wind tunnel experiments and computational fluid dynamics (CFD) using an unsteady Reynolds-averaged Navier-Stokes (RANS) turbulence model. Distinct vortex formation patterns are observed in the flow field surrounding the stationary inclined profile. When the cavity of the profile faces away from the incoming flow, large vortices develop behind the profile. Conversely, when the cavity is oriented towards the oncoming flow, these vortices form within the cavity. Notably, due to the slow movement of these large vortices through the cavity, the frequency at which vortices are shed in the negative inclination case is lower compared to the positive inclination, where they form in the wake. Wind tunnel experiments reveal an intermittent transition between the two vortex formation patterns at zero inclination. Large vortices sporadically emerge both in the cavity and behind the profile. The simulation results demonstrate that when these large vortices occur at a frequency close to the structure's natural frequency, they induce prominent pitch vibrations. This phenomenon is also sought after and presented in coupled vibration experiments. Additionally, the simulations indicate that when the natural frequency of the structure is considerably lower than the vortex shedding frequency, this type of vibration can be observed.

• 한국병원경영학회지
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• 제10권1호
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• pp.48-70
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• 2005

The purpose of this study was to make an analysis of the impact of the DRG payment system on medical care pattern and cost of cataract surgery in a general hospital. The subjects were 173 patients whose DRG severity grade was zero, selected from among the hospitalized who underwent cataract surgery before and after the joining to the demonstrational operation of the third year DRG payment system. Their medical records and the details of their medical bills were examined to find out the length of hospital stay, medical care pattern provided to them, the cost of medical care, and the quality of medical care. The length of stay and the amount of medical care supplied during being in hospital dropped significantly for both single-eye and double-eyes cataract surgery groups. The amount of antibiotic use went down during the hospitalization and upon discharge from the hospital, but decreased after discharge. The total medical bills and the rate of basic examination implementation increased in the OPD before hospitalization but after discharge dropped. For double-eyes cataract patients, the rate of double-eyes cataract surgery went down. The total medical bills of DRG payment system converted into the fee-for-service system was greater by 113.3% for the single-eye cataract surgery group and by 102.9% for the doble-eyes cataract surgery group, compared to that by the fee-for-service. The contribution shared by the insurance corporation increased for both single-eye and double-eyes cataract surgery groups, but the copayment by the insured went down. Regarding the treatment outcome, no difference was found in complication rate, resurgery rate and mortality rate before and after the joining to the DRG payment system was implemented. The use of special lens lessened significantly. The amount of medical care supplied during hospitalization decreased but the complication rate didn't increase. But the increased use of low-price artificial cataract and the avoidance of double-eyes cataract surgery was observed. The phenomenon decreased number of OPD visit and the decreased total medical bills of OPD care after discharge in this hospital required further evaluation.

• 대한토목학회논문집
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• 제32권4B호
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• pp.243-251
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• 2012

국립해양조사원의 해운대 부이로 부터 관측된 자료와 CCTV 영상자료를 분석하고 수치실험을 수행하여 해운대 해변에서 발생하는 이안류의 특성을 연구하였다. CCTV 영상자료를 분석한 결과로 부터 이안류가 발생할 때 규칙파에 가깝고 진행방향이 약간 다른 파랑이 중첩되어 입사되고 있는 것을 관찰할 수 있었으며, 부이 관측자료의 웨이브릿 분석으로부터 한 주기에 파랑에너지가 집중된 협대역 스펙트럼을 확인할 수 있었다. 이로부터 이미 알려진 이안류 발생 메커니즘가운데 하나인 벌집구조의 절점선 영역을 통한 이안류의 발생이 해운대 이안류의 주요한 발생 메커니즘임을 추론할 수 있었다. 이러한 이안류 발생 메커니즘은 다음과 같이 설명할 수 있다. 진행방향이 약간 다른 규칙파가 해안으로 전파될 때 서로 중첩되어 비선형 상호작용으로 파봉선이 벌집구조 형상으로 변형된다. 여기서, 파고가 영(zero)인 절점선이 해안선에서 외해방향으로 발달하게 된다. 파고가 상대적으로 작은 이 절점선 영역을 향하여 연안류의 질량수송이 집중되며 일시에 외해로 이안류를 발생시키게 된다. 벌집구조 파봉형상 입사파에 의한 이안류 발생을 재현하기 위해 완전 비선형 Boussinesq 방정식 모형을 이용해 수치모의를 수행하였다. 이 수치모의로부터 진행방향이 서로 다르므로, 그리고 일방향 파랑이 수중천퇴에 의하여 변형되므로 발생된 벌집구조 현상에 의하여 이안류가 잘 발생함을 확인하였다.

• 폴리머
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• 제27권1호
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• pp.9-16
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• 2003

골다공증 치료제 이프리플라본 (IP)은 조골세포의 분화와 증식을 자극하고 에스트로겐의 존재로 칼시토닌 분비를 강화한다. 조절 가능한 생분해성과 생체적합성으로 인하여 락타이드-글라이콜라이드 공중합체 (PLGA)는 약물방출조절을 연구하는데 가장 적합한 고분자중의 하나이다. 본 연구에서 IP가 함유된 PLGA 미립구는 일반적인 O/W 용매 증발법으로 제조하였으며, 미립구의 크기는 5~200 $mu extrm{m}$의 범위에 있었다. 미립구의 형태는 SEM으로 관찰하였고, 생체외 방출실험에서 IP 방출량은 HPLC로 분석 하였다. 젤라틴 및 PVA등의 유화제 사용으로 가장 높은 약물 포접율을 얻을 수 있었다. 미립구의 형태, 크기 및 약물 방출 패턴은 PLGA의 분자량 (8, 20, 33 및 90 kg/mol), 고분자용액의 농도 (2.5, 5, 10 및 20%), 유화제의 종류 (PVA, gelatin 및 Tween 80), 초기 약물 함유량 (5, 10, 20 및 30%) 및 교반속도 (250, 500 및 1000 rpm) 등과 같은 여러 제조 변수들에 의하여 조절할 수 있음을 알 수 있었다. 생체외 방출실험에서 IP 방출은 제조조건을 조절함으로써 거의 영차방출 형태로 30일 이상으로 지속적이었다 또한, XRD와 DSC로 IP 함유 PLGA 미립구의 물리화학적인 성질을 조사하여 방출메카니즘을 고찰하였다.