• Journal of the Korean Society for Precision Engineering
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• v.13 no.5
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• pp.95-103
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• 1996

This paper describes a computer aided design system for spur and helical gears. To establish the appropriate program, an integrate approach based on a rule-base system was adopted. This system is implemented on the personal computer and its environment is a commercial CAD package called AutoCAD. This system includes a main program and five sub-modules such as data input module, tooth profile drawing module, strength calculation module, and drawing edit module. In the main program, all the sub-modules are loaded and the type of gear and tooth profile are selected. In the data input module, the variables which are necessary to the design of gear are selected from the database. In the drawing module, from the calculated results, the required gear tooth is produced on the screen. The developed system that aids gear designer provides powerful capabilities for gear design.

• The Journal of the Acoustical Society of Korea
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• v.25 no.8
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• pp.389-394
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• 2006

Mid-Frequency bistatic reverberation level is modeled using ray theoretic algorithms. The algorithm assumes multiple forward/backward scatter along with reciprocity in the Propagation paths. The environments modeled are assumed to be range independent in bathymetry, bottom scattering and surface scattering. Mid-Frequency bistatic scattering algorithm is used as a scattering model. A comparison of predicted reverberation versus time with measured data is presented to verify the bistatic reverberation model. The result demonstrates that it is possible to obtain reasonable reverberation Predictions in experimental site.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.37 no.8
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• pp.1029-1033
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• 2013

Elliptical gear is used as a rotor of oval flowmeter. The elliptical gear can assist water flow-rate measurement by the space of the elliptical shape. Presently, elliptical gears have been processed using hob tool imported from Japan. But if it were not for the technical cooperation with Japan company, the Elliptical gears can't be processed. The purpose of this study is developing a domestic technology for elliptical gears and overcoming the dependence of foreign technical skills. It will bring the import substitution effect. In case of pressure angle $20^{\circ}$, the elliptical gears have an interference of tooth. The increase of pressure angle makes the root of a tooth thick and the top of tooth thin. By results of this study, tooth of elliptical gear was designed and verified through the 2D and 3D simulation.

• Journal of the Korean Operations Research and Management Science Society
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• v.36 no.4
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• pp.91-107
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• 2011

The importance of service industries is growing as the portion of the service sector increases fast in the recent decades. This research deals with service prototyping and testing in a service laboratory. While products are generally tested through prototyping in new product development processes, services are difficult to test because of the characteristic of service, intangibility. A service laboratory, named s-Scape, is the experiment environment which has been developed to test services in virtual space for the purpose of analysis and improvement of real-world services such as hospitals and automobile show rooms. In this research, we present a service prototyping tool and language to support service test in the service laboratory. We first analyze key elements of service prototypes, and then design the service prototype diagram (SPD) and the service prototype description language (SPDL). SPD, which is a variant of the service blueprint, is a graphical tool to be used to generate SPDL. SPDL is an executable language of describing a service prototype of a real-world service in extensible markup language (XML) to experiment the service environment in virtual space. SPD reflects the control and interface of virtual reality devices, as well as key elements of service modeling. SPD represents a service process in which service providers and customers interact with each other in a service scape.

• Proceedings of the Plant Resources Society of Korea Conference
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• 2010.05a
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• pp.8-8
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• 2010

자원식물을 소재로 이용하는 생물산업은 21세기 경제성장을 주도할 핵심기간산업이며, 미래형 고부가가치산업이다. 현재 지구상에는 약 55만종의 식물이 존재하는 것으로 알려져 있으나, 인간의 손길이 닿지 않은 천연 강우림 등의 미개척지가 상당수 존재하고 있어 더욱 많은 종들이 존재할 것으로 추정된다. 자원식물들 중에는 작물로의 개발이 가능하거나, 개발할 필요성이 높은 식물들이 많이 있다. 자원식물들은 예로부터 식용, 약용, 관상용, 유지용, 기호용, 밀원용, 섬유용, 향신료용, 향료용, 당료용, 호료용, 염색용, 수지용, 탄닌용 등으로 구분되어 이용되어 왔다. 자원식물은 종에 따라 꽃, 줄기, 잎, 뿌리 및 종자 등 부위별로 다양하게 산업적 소재로 활용되어 왔다. 최근에는 건강에 관한 관심이 급증하면서 다양한 건강 기능성 상품이 개발되고 있으며, 관련 시장이 급속하게 성장하고 있다. 특히 자원식물 등 천연물을 소재로 한 건강 기능성 상품은 안전성이 보장되며 우수한 생리활성이 있는 것으로 밝혀지면서, 자원식물을 소재로 한 건강 기능성 상품의 개발에 대한 수요가 증가하고 있는 실정이다. 따라서 다양한 자원식물을 대상으로 이들의 활용가치를 분석하여 상품화할 수 있는 방법의 개발이 절실히 필요하다. 또한 주 5일제 실시 및 여가활용에 관한 관심이 급증하면서 농촌 경관산업에 대한 수요가 증가하고 있다. 농촌 경관산업은 국민의 여가선용 및 복지향상에 효과적일 뿐 아니라 지역주민과 관광객이 함께 즐길 수 있는 관광산업으로써 지역 이미지 강화를 통한 지역 홍보, 지역 내 일자리 창출 및 경관산업에 사용된 생물소재를 이용한 바이오산업의 활성화 등의 장점을 지니고 있다. 또한 농촌 경관산업은 자연과 농촌을 활용한 자연 친화형 관광단지를 조성하여 친환경, 고부가가치형 종합산업을 추구하는 추세이다. 그러므로 경관산업 및 이를 활용한 바이오산업의 소재로써 자원식물의 역할은 매우 클 것으로 생각된다. 특히 각 지역에 자생하는 고유의 자원식물을 활용하면 지역 특화 경관산업 및 바이오산업의 발전에 크게 이바지 할 수 있으며, 이로 인하여 지역 경제 활성화 및 친환경 건강 기능성 상품에 대한 수요를 충족시킬 수 있을 것으로 기대된다. 따라서 친환경 건강 기능성 소재 개발과 농촌 경관산업을 활용한 생물산업에 적용할 수 있는 산업적 가치가 우수한 자원식물의 다양한 기능을 분석하고, 각 자원식물별로 특성에 맞는 개발 방안을 구축하여 다양한 산업화의 소재로 활용하여야 할 것으로 생각된다.

• Journal of the Korean Society for Precision Engineering
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• v.23 no.9 s.186
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• pp.54-60
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• 2006

Fitting process carried out in automobile transmission assembly line is classified into three classes; heat fitting, press fitting, and their combined fitting. Heat fitting is a method that heats gear to a suitable range under the tempering temperature and squeezes it toward the outer diameter of shaft. Its stress depends on the yield strength of gear. Press fitting is a method that generally squeezes gear toward that of shaft at room temperature by press. Another method heats warmly gear and safely squeezes it toward that of shaft. Warm shrink fitting process for automobile transmission part is now gradually increased, but the parts (shaft/gear) assembled by this process produced dimensional changes of gear profile in both radial and circumferential directions. So that it may cause noise and vibration between gears. In order to solve these problems, we need an analysis of warm shrink fitting process, in which design parameters are involved; contact pressure according to fitting interference between outer diameter of shaft and inner diameter of gear, fitting temperature, and profile tolerance of gear. In this study, an closed form equation to predict contact pressure and fitting load was proposed in order to develop optimization technique of warm shrink fitting process and verified its reliability through the experimental results measured in the field and FEM, that is, thermal-structural coupled field analysis. Actual loads measured in the field have a good agreement with the results obtained by theoretical and finite element analysis and also the expanded amounts of the gear profile in both radial and circumferential directions are within the limit tolerances used in the field.

• Journal of Korean Foot and Ankle Society
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• v.17 no.1
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• pp.28-33
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• 2013

Purpose: In previous study, the frequency of osteoarthritis and discomfort were high in ankle fracture-dislocation but detail results about ankle fracture-dislocation has rarely been investigated. In this study, we retrospectively analyze the outcome of the operative treatment of ankle fracture with dislocation for over-2 years follow up. Materials and Methods: There were 47 cases of ankle fracture-dislocation in our hospital from March 2007 to May 2010. We investigated 20 patients who underwent operation and were possible for over-2 years follow up. The result was estimated with the direction of dislocation, fracture type, the time of bone union and post-traumatic osteoarthritis with plain radiologic images. In clinical assessment, we statistically evaluated the function and pain through AOFAS score and Olerud & Molander scoring system. Results: By Lauge-Hansen classification, there were 13 cases(65%) of pronation-external rotation and 6 cases(30%) of supination-external rotation, 1 case(5%) of supination-adduction. AOFAS score was 85.5, and Olerud & Molander score was "excellent" in 8 cases, "good" in 5 cases, "fair" in 3 cases and "poor" in 4 cases. Postoperative complications in 4 cases revealed post-traumatic arthritis. All kinds of lateral dislocation of ankle fracture was 15 cases and the most common. Of these, all 3 cases, anterolateral dislocation showed post-traumatic osteoarthritis. Conclusion: In ankle fracture-dislocation, post-traumatic osteoarthritis occurred in 4 of 20 patient(20%). Especially, the possibility of post-traumatic osteoarthritis was more in cases of anterolateral or lateral dislocation. So, it must be needed that deliberate examination, for example, preoperative MRI and sufficient explanation to patient. Also, we have to follow up the patients carefully.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.35 no.11
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• pp.1453-1459
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• 2011

A roller pinion gear (RPG) system composed of either a pin or a roller and its conjugated cam gear can improve the gear endurance from that of a conventional gear system by reducing the sliding contact while increasing the rolling motion. In this paper, we first proposed the exact cam gear profile and the self-intersection condition obtained when the profile shift coefficient is introduced. Then, we investigated the Hertzian contact stresses and the load stress factors while the varying the shape design parameters to predict the gear surface fatigue life, which is strongly related to the gear noise and vibration at the contact patch. The results show that the pitting life can be extended significantly by increasing the profile shift coefficient.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.15 no.2
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• pp.66-71
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• 2016

For the manual transmission gearbox used in the automotive industry, gear meshing transmission error is the main source of noise known as gear whine, and radiated gear whine noise plays an important role in the whole gearbox. Therefore, in order to keep competitive in the automotive market, the NVH performance of transmission gearboxes is increasingly important for automotive manufacturers when a new product is developed. In this paper, in order to achieve an optimized tooth contact pattern, gear tooth modification is applied to make up for the deformation of the teeth owing to load. A five-speed MT gearbox is firstly modeled in RomaxDesign software and the prediction of transmission error under the loaded torques is studied and compared. From the simulation, the transmission error and maximum contact stress are also simulated and compared after tooth modification of the loaded torques. Finally, the simulation results are used to optimize the whole gearbox design and the final gearbox prototype is testified to obtain NVH performance in a semi-anechoic room.

• Korean Journal of Food Science and Technology
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• v.10 no.1
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• pp.57-62
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• 1978

The morphology and chemical properties of bracken (Pteridium aquilinum) root starch were investigated. The starch granules were mainly sphere and cocoon with the diameter of $5-12\mu$. Polarized micrograph indicated that the starch granule had a hilum at the center of granule, showing a crossed-birefringence. X-ray diffraction pattern demonstrated that the granules showed B-type. The density of the starch was 1.49 and the amylose content was 22%. The ferricyanide number and alkali number were 0.292 and 11.03, respectively. Proximate analysis showed that the starch contained 0.52% lipid, 0.63% ash and 150ppm phosphorus of which over 80% were found in the amylopectin fraction. The iodine affinity and molecular weight of amylose were 16.1 and 83,000 respectively. The degree of branching and glucose units per segment of amylopectin were 3.7% and 27, respectively.