• 한국한의학연구원논문집
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• 제12권1호
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• pp.39-48
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• 2006

The Following is a list of specific external and internal morphology of Rheum palmatum L. and R. undulatum L. in Rhei Rhizoma. 1. For the original plants of Rhei Rhizoma in the literatures. 18 plants are reported. 2. The external characteristics of original plant : R. palmatum has a large palmate leaf, its petiole of radical leaf has a simple bristle and its flower is purple and pink color. Whereas R. undulatum has a medium ovate leaf, its petiole of radical leaf is purphish, its stem leaf surrounds a half of stem and its flower is yellowish white color. 3. The character of herbal states : a. diameter and size-- R. palmaum is bigger and heavier than R. undulatum. b. in section--R. palmatum is dark brown color, R. undulatum is bright brown color Fibrovascular bundle is arranged in circle shape in R. patmatum. R. undulatum shows a distingushed wheel shape. 4. The internal characteristics : R. palmatum has a large intercellular space of cork layer, its cambium is clear and a xylem medullary ray is comparatively tight, Whereas R. undulatum has a tight intercettular space of cork layer., its cambium is a few clear and xylem medullary ray is verty tight. As these results, additional study is required to distinguish herbs and their effect among many kinds of same genus-degree of relatedness.

• 한국기계가공학회지
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• 제8권2호
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• pp.46-52
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• 2009

Drilling operation is such an important machining process, which has been wildly applied to the industry, occupied over 30% of whole industry. However, there are many aspects of drilling process should be improved, such as increases of thrust force, surface roughness, and roundness, ect. In this study, we are aiming to reduce the thrust force, surface roughness, and roundness in drilling process. For this purpose, multi facet drills (MFD) of three types that are modified from standard drill (STD) are developed. The first type is multi stair drill (MSD) with shape of stair on relief plane. The second type is rough facet drill (RFD) with shape of round on relief plane. The third type is rough flute drill (RFLD) with shape of round on flute plane. For three types of MFD, we were carried out performance evaluation from the perspective of thrust force, surface roughness and roundness of machined hole. From obtained result, we could confirmed that performance of rough flute drill (RFLD) type is most excellent.

• 한국정밀공학회지
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• 제26권5호
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• pp.87-95
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• 2009

This research introduces the efficient modeling and manufacturing method using reverse engineering combined with rotational simulation of a pair of screw and mill-turn machining realized a proposed NC program. Because previously developed model had insufficient flow measuring accuracy, we considered that matter in the aspect of method of modeling and performance test. For that reason we modified the modeling which could minimize a gab between male and female screw, and developed precise tester which consists of constant tank, flowmeter and load cell, etc., and then conducted the test for defining characteristic and accuracy of flowmeter and repeated same test 5-times. Consequently we could obtain satisfied measuring accuracy and reproducibility indicated in the catalog of master model. Hence we give our conclusion as to the validity of developing accurate screw type flowmeter using the proposed process such as reverse engineering, mill-turn machining and precise performance test.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2009년도 제40회 하계학술대회
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• pp.101_102
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• 2009

KSTAR(Korea Superconducting Tokamak Advanced Reseach)장치는 차세대핵융합연구장치로써 30개의 초전도자석으로 구성된다. 이 초전도자석에 전원을 공급하게 되는 PF (Poloidal Field) MPS(Magnet Power Supply)는 12상 Pulse 운전을 하게 되는데 이때 $h=kp{\pm}1$의 특성고조파와 90%에 가까운 무효전력이 발생되어 KSTAR 전력계통과 인근 부하장치에 치명적인 영향을 줄 수 있어 고조파와 무효전력을 동시에 보상할 수 있는 최적의 무효전력보상장치의 도입은 필연적이다. 본 논문에서는 KSTAR 1st Plasma 실험시의 무효전력과 고조파를 저감하기 위해 설치했던 즉, 1단계 기계식 스위칭에 의한 RPC(Reactive power compensator)의 보상특성의 평가결과를 기반으로 KSTAR 2009년 Plasma 실험에 대비하여 이의 운전특성과 설치 공간에 따르는 제약 등을 고려하여 최적의 RPC 설계를 도출하기 위해 실시한 TSC(Thyristor Switch Capacitor)기반의 RPC[1] 모의해석 결과와 기술적 사항을 소개하고자 한다.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2009년도 제40회 하계학술대회
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• pp.85_86
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• 2009

핵융합반응은 초고온의 플라즈마 상태에서 가벼운 원자핵들이 융합하여 무거운 원자핵으로 바뀌는 현상으로, 이 과정에서 감소된 질량이 막대한 에너지로 변환되는데 이를 핵융합에너지라고 한다. 핵융합에너지는 인류의 에너지 위기를 극복할 수 있는 최적의 대체에너지이며, 무한, 청정, 고효율에너지이다. 이에 국가핵융합연구소(NFRI)는 Green Energy 의 개발과 핵융합에너지 상용화 기술을 개발하기 위해 핵융합연구장치인 KSTAR(Korea Superconducting Tokamak Adavanced Research)를 제작하여 장치의 운전연구 및 기술 확보에 힘을 쏟고 있다. 또한 핵융합 관련 파생기술을 활용한 첨단 신사업 창출에 기여하고 있다. 본 논문에서는 KSTAR 1st Plasma 실험 시 KSTAR 장치에 전력을 공급하기 위한 전력설비 현황, 전력품질분석, 전력사용량 분석을 통해 향후 KSTAR 장치 운전을 위해 필요한 수전설비 증설, 무효전력보상장치 증설 등과 같은 전력계통의 효율화와 안정화를 위한 개선사항에 대해 기술하였다.

• 한국정보과학회논문지:컴퓨팅의 실제 및 레터
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• 제14권7호
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• pp.713-717
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• 2008

최근 플래시 메모리 용량이 증가함에 따라 대용량의 데이타를 빠르게 검색하기 위한 효율적인 인덱싱 방법의 필요성이 증가하였다. 플래시 메모리는 기존 저장매체와 다른 여러 가지 하드웨어적인 특성이 있다. 특히, 쓰기 연산과 소거 연산은 비용이 매우 크고, 덮어쓰기 연산이 불가능하다. 본 논문에서는 플래시 메모리에 저장되는 데이타에 대해여 발생하는 잦은 쓰기 연산을 감소시켜 다양한 연산을 효율적으로 처리하는 인덱스 구조를 제안한다. 본 논문에서는 성능 평가를 통해 제안하는 인덱싱 방법의 우수성을 보인다.

• 한국기계가공학회지
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• 제14권1호
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• pp.123-129
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• 2015

In general, recent critical studies of five-axis machine have tended to center on the question of effective machining to realize complex shape parts. However, the hydrostatic bearing and journal bearing, both of which are involved in the complex process of dividing the processing of internal precision-shape machining, must be optimized. Although the angle head is designed to machine the internal shape as it approaches the inner diameter of the work piece, research on the angle head in five-axis machining has received only minimal attention in domestic industries. In this study, an angle head which is optimized for effective internal shape machining is developed. In pursuit of this purpose, 3D and 2D designs of the angle head for five-axis machining are devised. Reliability is secured through static performance tests and machining accuracy evaluations of the angle head in keeping with the machining accuracy standard of 0.2mm for hydrostatic bearings.

• 한국환경과학회지
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• 제25권4호
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• pp.589-601
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• 2016

This study aims to analyze the priority of regional climate change policy utilizing AHP (analytic hierarchy process) at the area of Metropolitan City of Incheon. It derives four factors at first hierarchical level, at which level the analysis of pair-wise comparison indicates that industrial sector, energy sector, climate change response, and green culture policy are considered important in that order. It also ends up with sixteen factors at second level. The result of comparison analysis between all factors reveals that investment promotion in green technology R&D is considered the most significant factor of all, followed by establishment of green enterprise support system, electricity-efficiency enhancement support project and build-up of green culture policy governance. The result implies that diverse promotional policies have to incorporate business, institutional, and cultural aspects for sustainable climate change policy of regions. The contribution of this study is that it highlights the need to include regional characteristics in deciding priority among policy options for them to be effective.

• 한국기계가공학회지
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• 제19권4호
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• pp.71-78
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• 2020

The rotary feed axes of a 5-axis machine tool can increase the freedom of the tool posture, while reducing feed speed and rigidity. In addition, as a ball-end mill is inevitably used during machining by rotational feed, the step-over length is reduced compared to the flat-end mill, thereby reducing the material removal rate. Therefore, this study attempts to improve the material removal rate, feed speed, and machining stability using the corner radius flat-end mill and a fixed controlled machining method for the rotary feed axes during roughing. In addition, the tapered ball-end mill and simultaneously controlled machining method for the rotary feed axes were used for finishing to improve the propeller's 5-axis machining efficiency by enhancing the surface quality. In order to create the tool path effectively and easily, we propose a specific approach for using the propeller's geometric properties and evaluate the effectiveness of the proposed method by comparing it with the method of the dedicated module.

• 한국공작기계학회논문집
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• 제15권3호
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• pp.53-58
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• 2006

This study deals with the method of post-processing in the automatic tool path generation for 5-axis NC machining. The 5-axis NC machining cannot only cope with the manufacturing of complicated shapes, but also offers numerous advantages such as reasonable tool employment, great reduction of set-up process and so on. Thus 5-axis NC machining has been used for aircraft parts, mold and die as well as for complicated shapes such as impeller, propeller and rotor. However, most of the present CAM systems for 5-axis NC machining have limited functions in terms of tool collision, machine limits and post-processing. Especially 5-axis machine configurations are various according to the method which the rotational axes are adapted with the table and spindle. For that reason, In many cases the optimal numerical control (NC) data cannot be obtained or considerable time is consumed. To solve this problem, we applied a general post-processor for 5-axis NC machining. The validity of this post-processor should be experimentally confirmed by successfully milling to a helix shaped workpiece.