• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2009.10a
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• pp.176-181
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• 2009

In this article, excitation forces due to unbalance mass in a flywheel energy storage system will be discussed, which mainly consists of a composite flywheel and active magnetic bearings and a motor/generator. Unbalance mass causes moments as well as centrifugal forces to the center of the flywheel when the flywheel rotates. The moment excites the flywheel to revolve in the shape of conical revolution and in real operation, the flywheel shows an aspect that conical revolution is a main mode when system failure occurs. Although there are several excitation sources to the flywheel including unbalance mass, an excitation from motor and control issues of the magnetic bearings, we could infer unbalance mass is the main cause of the failure from a comparison between a composite flywheel and a steel flywheel in the same condition. In this of view, excitation forces and moments induced by unbalance mass should be carefully considered in dynamics of the flywheel so that the energy storage system can be operated in more stable conditions.

• Journal of Biosystems Engineering
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• v.26 no.2
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• pp.131-140
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• 2001

This study was conducted to develop a garlic separator which could to reduce the labor in preparation of seeding. After consideration of the design criteria of a garlic separator such as no additional conveying device, simple construction and operation, enhancement of separating efficiency, reduction of damage, degree a rotating corn type garlic separator was designed. The effects of design parameters such as height and angle of the inner and outer corns, rotating speed of inner corn on the separating performance of the prototype were estimated. In performance was compared with manual work. The results are summarized as follows. 1. Garlic bulbs were separated by a spiral movement in the gap between inner rotating corn and outer fixed corn. At constant feed rate of garlic bulbs, the capacity of garlic separation increased with increase of rotating speed of inner corn. Especially, the capacity was very high at the rotating speeds of 300 and 400rpm. 2. The damage degree of separated garlics increased with rotating speed of corn within 10%. Above 300rpm, separability of Uisung garlic was about 100% and incomplete separation of Namdo garlic was within 2%. 3. The capacity of prototype garlic separator developed in this study was 30 times as large as that of human being.

• Journal of Biosystems Engineering
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• v.32 no.2 s.121
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• pp.84-90
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• 2007

This study was conducted to design and manufacture a final prototype of garlic separator and to evaluate its performance. The performance of garlic separation was compared with manual separation. The final prototype for garlic separation consists of bucked-elevator device for automatic feed of garlic, rotating cone typed device, blower, and power transmission device. The optimal condition of outlet clearance was 19 mm and in this clearance, the proportions of fragment garlic separated in the large quality of Namdo garlic and all quality of Uiseong garlic were above 95% and above 85%, respectively. All proportion of damaged garlic was below 5% for all variety and quality. The garlic separation capacities of this developed machine were 310 kg/h for Namdo garlic and 293.6 kg/h for Uiseong garlic in the large quality. Capacities of final prototype compared with human being were $12.9{\sim}19.6$ times for Namdo and $24.2{\sim}31.7$ times Uiseong garlic, respectively.

• Journal of the Korean Society of Food Science and Nutrition
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• v.19 no.6
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• pp.612-616
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• 1990

The addition of water into oil phase containing hydrophobic emulsifier while stirring forms W/O emulsions. When dispersed phase increase up to a certain extent, phase inversion into O/W emulsions occurs and just before phase inversion O/W/O emulsions exist in a mixed state with W/O emulsions. Thus this experiment was carried out to examine O/W/O emulsions formation in W/O emulsions. The viscosity of sample emulsions(water phase： $H_2O$, oil phase : TGCR-containing olive oil) was measured at the shear rate of 1.92 to 384 per second and at temperature of 25$\pm$0.1$^{\circ}C$, and the development of O/W/O emulsions evaluated from the difference between theoretical and measured values by substituting measured value for Mooney's equation. The formation of O/W/O emulsions tended to be high in sample emulsions just before phase inversion and increase with decreasing TGCR concentrations. This result suggests that high viscosity observed right before phase inversion may also be caused by the formation of O/W/O emulsions.

• The korean journal of orthodontics
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• v.37 no.1 s.120
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• pp.5-15
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• 2007

Objective: The purpose of this study was to evaluate the mechanical performance of mini-screws during insertion into artificial bone with use of the driving torque tester (Biomaterials Korea, Seoul, Korea), as well as testing of Pull-out Strength (POS). Methods: Experimental bone blocks with different cortical bone thickness were used as specimens. Three modules of commercially available drill-free type mini-screws (Type A; pure cylindrical type, Biomaterials Korea, Seoul, Korea, Type B; partially cylindrical type, Jeil Medical, Seoul, Korea, Type C; combination type of cylindrical and tapered portions, Ortholution, Seoul, Korea), were used. Results: Difference in the cortical bone thickness had little effect on the maximum insertion torque (MIT) in Type A mini-screws. But in Type B and C, MIT increased as the cortical bone thickness Increased. MIT of Type C was highest in all situations, then Type B and Type A in order. Type C showed lower POS than Type A or B in all situations. There were statistically significant correlations between cortical bone thickness and MIT, and POS for each type of the mini-screws. Conclusion: Since different screw designs showed different insertion torques with increases in cortical bone thickness, the best suitable screw design should be selected according to the different cortical thicknesses at the implant sites.

• Proceedings of the Korean Society for Agricultural Machinery Conference
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• 2017.04a
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• pp.80-80
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• 2017

국내에서 대부분 생산되는 사료(사일리지) 수확 작업은 베일 생산 및 비닐 래핑 작업이 독립적으로 수행되고 있어서 비효율적이다. 본 연구에서 개발한 조사료 수확기는 수집, 롤링, 베일 네트 생성, 래핑, 래핑 종료 및 베일 방출작업을 통합적으로 수행하도록 설계-제작하였다. 통합형 다목적 조사료수확기의 설계는 3D 디자인 툴 (CATIA V5R18)을 이용하여 실시하였으며, 기구부 23 파트 어셈블리, 전기제어 어셈블리, 유압요소기술을 통합하여 통합시작기를 제작하였다. 기초 프레임, 오거장치파트, 픽업장치파트, 하부롤러파트, 상부롤러파트, 하부 프레임 및 주행부 파트, 래핑회전파트, 롤러부 구동 동력부, 유압파트, 전기제어파트, 드로우바파트, 체결 및 컨트롤러 파트 등 25개 파트로 구성되어 있다. 본 연구에서 개발한 시작기의 견인력 및 소요동력 분석은 선행 연구에서 사용한 Brixius (1987) 제안 모델을 체택하여 분석하였다. 이 Brixius 제안 모델은 견인력 예측에서 토양변수 및 토양강도 특성을 나타내는 원추지수 (Cone Index, CI)를 이용하여 트랙터의 견인력 예측에 사용하였다. 또한 트랙터-조사료수확기 시스템의 소요 견인력을 예측하는데 있어, 트랙터-조사료수확기 시스템이 운용되는 토양조건과 트랙터의 마력에 따른 소요 견인력 특성을 분석하기 위해 대표적으로 3수준의 토양조건 (CI: 356 kPa, 543 kPa, 1,429 kPa)을 적용하였으며, 베일의 개당 최대무게는 최고 수준인 옥수수 기준으로 800 kgf를 적용하였다. 본 연구에서 적용된 3수준의 CI 조건은 연구팀에서 선행연구과정 (토양특성에 따른 최적 경운작업 시스템 개발, 2006)에서 분석한 전국 10개 지역의 33개 지점의 경반층 CI지수의 측정범위인 1,050-3,170 kPa에 대해 견인력이 많이 소요되는 열악한 조건 수준을 적용하였다. 각 작업에 사용된 소요동력은 베일 작업시 (ASABE D497.7, 2011) 그리고 래핑작업시 (Zhortuylov et al., 2013)를 사용하였으며 두 소요마력을 트랙터-조사료 수확기 시스템의 필요 소요마력의 합계로 계산하였다. 트랙터-조사료수확기 시스템의 최소 소요 동력, 차축 소요 동력과 PTO 소요 동력을 Zoz and Grisso (2003)을 이용하여 계산하였다. 연구에서는 기본적으로 ASAE의 작업속도 및 작업효율을 적용하였는데, 적용된 조사료수확기의 현장 작업효율은 60-86%의 범위이고 일반적으로 70%를 적용하고 이때 작업속도는 2.5-8.0 km/h이며 전형적으로 5.0 km/h를 기준하고 있다. 자주식 (SP; sief-propelled machine) 조사료수확기의 경우 작업속도가 2.5-10.0 km/h의 범위에서 작업효율은 60-85% 범위이다. 적용되는 조사료 수확기의 작업효율인 60-85% 범위에서 일반적으로 적용되는 작업효율인 70%를 적용하면 트랙터의 소요동력은 95hp를 적정 작업환경으로 하였다.

• Journal of Biomedical Engineering Research
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• v.22 no.5
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• pp.449-458
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• 2001

This is a test report of system efficiency for the moving-actuator type Bi-ventricular assist device (AnyHear $t^{MT}$ ) Seoul National University). $AnyHeart^{TM}$), as an energy converter. utilities a brushless DC motor(S/M 566-26A. Sierracin/ Magnedyne, Carlsbad, CA. U.S.A.) generating their pendulous motion in the epicyclic gear train. It is necessary to know about the overall efficiency of the system. The system is subdivided into three parts: motor part, actuator part and blood sac part (including valves, etc.) according to system mechanism. The motor was operated with a variable range of torque. angular speed and width of voltage Pulse In this report. $AnyHeart^{TM}$ is focused on the efficiency of the motor and actuator parts. 4 $\ell/min$ pump output. which is normal condition of $AnyHeart^{TM}$ system, the total system efficiency is 8%, which is composed of 50%, 85% and 17% efficiency (motor Part, actuator Part and blood sac Part) respectively. In the analyzed result. applied input voltage on normal condition of $AnyHeart^{TM}$ is determined. Also speed Profile with considering filling state of blood sac is Provided. In the test of the in vitro mock circulation. some experimental results are Provided to demonstrate the effectiveness of the Presented approach.

• The Journal of Korean Academy of Prosthodontics
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• v.54 no.2
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• pp.110-119
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• 2016

Purpose: This study is aimed to assess changes of stress distribution dependent on different connection lengths and placement of the fixture top relative to the ridge crest. Materials and methods: The internal-conical connection implant which has a hexagonal anti-rotation index was used for FEM analysis on stress distribution in accordance with connection length of fixture-abutment. Different connection lengths of 2.5 mm, 3.5 mm, and 4.5 mm were designed respectively with the top of the fixture flush with residual ridge crest level, or 2 mm above. Therefore, a total of 6 models were made for the FEM analysis. The load was 170 N and 30-degree tilted. Results: In all cases, the maximum von Mises stress was located adjacent to the top portion of the fixture and ridge crest in the bone. The longer the connection length was, the lower the maximum von Mises stress was in the fixture, abutment, screw and bone. The reduction rate of the maximum von Mises stress depending on increased connection length was greater in the case of the fixture top at 2 mm above the ridge crest versus flush with the ridge crest. Conclusion: It was found that the longer the connection length, the lower the maximum von Mises stress appears. Furthermore, it will help prevent mechanical or biological complications of implants.

• Journal of the korean academy of Pediatric Dentistry
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• v.40 no.4
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• pp.260-267
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• 2013

The aim of this study was to analyze the three dimensional characteristics of the size, shape and location of mesiodens and their effect on permanent teeth arrangement using Cone-beam computed tomography(CBCT). 191 patients under 15 years old who had visited the hospital between June 2006 and December 2012 and taken CBCT were investigated. Among them, 43 patients with diastema were analyzed to investigate the correlation between the amount of diastema and the mesiodens. The results showed that mesiodens were found in males 3.9 times more than females and found most in 7 years old. The mean length of mesiodens was 13 mm and the width was 6.8 mm. The conical shape comprised of 52.9%. Many mesiodens were located in the palatal side rather than the labial side and located vertically near the crown. 63.0% of mesiodens were reversed and the common complications were delayed eruption followed by diastema, and teeth rotation. And the amount of diastema had correlation with size and mesiodistal position of the mesiodens. The current study used 3D analysis to show the size and position of mesiodens and occurrence distribution of complication. Among these, the amount of diastema had shown the correlation with the size and mesiodistal position of mesiodens.