• 한국기계가공학회지
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• 제11권2호
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• pp.1-6
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• 2012

Recent ultra-precision machining systems have nano-scale resolution, and can machine various shapes of complex structures using five-axis driven modules. These systems are also multi-functional, which can perform various processes such as planing, milling, turning et al. in one system. Micro machining technology using these systems is being developed for machining fine patterns, hybrid patterns and high aspect-ratio patterns on large-area molds with high productivity. These technology is and will be applied continuously to the fields of optics, display, energy, bio, communications and et al. Domestic and foreign trends of micro machining technologies for flat molds were investigated in this study. Especially, we focused on the types and the characteristics of ultra-precision machining systems and application fields of micro patterns machined by the machining system.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2005년도 춘계학술대회 논문집
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• pp.1223-1227
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• 2005

Fine microgroove is the key component to fabricate micro-grating, micro-grating lens and so on. Conventional groove fabrication methods such as etching and lithography have some problems in efficiency and surface integrity. This study deals with the creation of ultra-precision micro grooves using non-rotational diamond tool and CNC machining center. The shaping type machining method proposed in the study allows to produce V-shaped grooves of $40\mu{m}$ in depth with enough dimensional accuracy and surface. For the analysis of machining characteristics in micro V-grooving, three components of cutting forces and AE signal are measured and processed. Experimental results showed that large amplitude of cutting forces and AE appeared at the beginning of every cutting path, and cutting forces had a linear relation with the cross-sectional area of uncut chip thickness. From the results of this study, proposed micro V-grooving technique could be successfully applied to forming the precise optical parts like prism patterns on light guide panel of TFT-LCD.

• 한국정밀공학회지
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• 제8권3호
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• pp.55-63
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• 1991

Transforming small ultrasonic energy into large mechanical energy is the essential feature of ultrasonic vibration in various application fields. This energy amplification can be obtained by achieving resonance condition between booster or tool horn and transducer. When it has uniform section with small sectional area, one dimensional analysis provides good estimation of the natural frequency of the horn. But, for arbitrary shape of horn, one dimensional analysis can no longer be applied. At present, designing tool horn whose natural frequency is identical to that of transducer requires serveral stages of trial and error in actual manufacturing process. In this paper, frequency analysis program is developed to easily predict the natural frequency of ultrasonic vibration cutting tool with axisymmetry and 3- dimensional shape using finite element method.

• International Journal of CAD/CAM
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• 제6권1호
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• pp.193-198
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• 2006

Plunge milling is the fastest way to mill away large volumes of metal in the axial direction. The residual volume (inaccessible volume by the plungers) is minimized when selecting a specific direction of filling. This direction is known as the optimal inclination angle for filling of the plunged area. This paper proposes a new algorithm to calculate the optimal inclination angle of filling and to fill the plunged area with multi-plungers sizes. The proposed algorithm uses the geometry of the 2D area of the shape that being cutting to estimate the optimal inclination angle of filling. It is found that, the optimal inclination angle for filling of the plunged area is the same direction as the longer width of the equivalent convex polygon of the boundary contour. The results of the tested examples show that, the residual volume is minimized when comparing the proposed algorithm with the previous method.

• 한국분말재료학회지
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• 제20권5호
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• pp.355-358
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• 2013

Micro trench structures are applied in gratings, security films, wave guides, and micro fluidics. These micro trench structures have commonly been fabricated by micro electro mechanical system (MEMS) process. However, if the micro trench structures are machined using a diamond tool on large area plate, the resulting process is the most effective manufacturing method for products with high quality surfaces and outstanding optical characteristics. A nonferrous metal has been used as a workpiece; recently, and hybrid materials, including polymer materials, have been applied to mold for display fields. Thus, the machining characteristics of polymer materials should be analyzed. In this study, machining characteristics were compared between nonferrous metals and polymer materials using single crystal diamond (SCD) tools; the use of such materials is increasing in machining applications. The experiment was conducted using a square type diamond tool and a shaper machine tool with cutting depths of 2, 4, 6 and 10 ${\mu}m$ and a cutting speed of 200 mm/s. The machined surfaces, chip, and cutting force were compared through the experiment.

• 공업화학
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• 제33권2호
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• pp.133-144
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• 2022

Fast-paced industrial and agricultural development generates large quantities of hazardous heavy metals (HMs), which are extremely damaging to individuals and the environment. Research in both academia and industry has been spurred by the need for HMs to be removed from water bodies. Advanced materials are being developed to replace existing water purification technologies or to introduce cutting-edge solutions that solve challenges such as cost efficacy, easy production, diverse metal removal, and regenerability. Water treatment industries are increasingly interested in activated carbon because of its high adsorption capacity for HMs adsorption. Furthermore, because of its huge surface area, abundant functional groups on surface, and optimal pore diameter, the modified activated carbon has the potential to be used as an efficient adsorbent. Metal-organic frameworks (MOFs), a novel organic-inorganic hybrid porous materials, sparked an interest in the elimination of HMs via adsorption. This is due to the their highly porous nature, large surface area, abundance of exposed adsorptive sites, and post-synthetic modification (PSM) ability. This review introduces PSM methods for MOFs, chemical modification of activated carbons (ACs), and current advancements in the elimination of Pb²⁺, Hg²⁺, and Cd²⁺ ions from water using modified MOFs and ACs via adsorption.

• 한국초지조사료학회지
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• 제13권4호
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• pp.257-267
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• 1993

본 시험은 여름철 고온기간중 예취시기와 예취높이가 orchardgrass의 목초 재생과 저장탄수화물 함량 및 수량에 미치는 영향을 구명하기 위하여 실시되었다. 시험설계는 3차 예취시기(7월 15일, 7월 25일, 8월 5일)를 주구, 3차 예취시 예취높이(3, 6. l0cm)를 세구로 하여 분할구 배치 3 반복으로 하여 1988년 장성실업고등학교 포장에서 수행되었다. 1. 고온기의 예취높이별 지표 및 지중(l0cm) 온도는 7월 15일 예취구와 7월 25일 예취구에서는 뚜렷한 차이를 보이지 않고 있는데 이는 장마의 영향으로 보이며, 8월 5일 예취구에 있어서 지표 및 지중온도는 여름철 예취높이가 높을수록 낮아지는 경향을 보였다. 2. 고온기 예취높이별 토양수분 함량의 변화는 예취높이가 높아질수록 토양수분 함량은 낮아지는 경향을 보였다. 3. 고온기 예취높이별 재생초장, 재생엽장 및 재생엽면적의 변화는 예취높이가 높을수록 생육속도가 빨라졌다. 4. 고온기 예취시기와 예취높이가 그루터기의 저장탄수화물 함량에 미치는 영향은 7월 15일과 7월 25일 예취구가 8월 5일 예취구에 비해 저장탄수화물이 예취전 상태로 회복되는 일수가 빨랐으며 저장탄수화물 축적량도 많았다. 5. 고온기 건물수량은 3차 예취시 8월 5일 예취구가 7월 15일과 7월 25일 예취구 보다 더 많았고 예취높이 3cm구가 6cm구와 l0cm구 보다 더 많았다. 그러나 4차 및 5차 예취시 건물수량은 7월 15일 예취구가 7월 25일과 8월 5일 예취구에 비하여 현저히 많았다. 본 시험의 결과를 종합하여 볼 때 여름철 고온기의 유리한 초지관리를 위해서는 예취시기에 관계없이 고온기 예취높이가 l0cm인 시험구가 재생, 탄수화물 축적 및 건물 생산량에서 바람직한 결과를 나타냈다.에 관계없이 무처리에 비해 발아율이 향상되었다. 평균발아 소요일수에 있어서도 Kinetin 과 NAA는 무처리보다 지연되는 경향이었으나 GA$_3$는 100 ppm 전처리시 무처리 대비 2.0일이 단축되었다. 6. PEG나 GA3의 종자 전처리는 수분장애 조건에서 공히 무처리에 비해 발아율이 향상되었고 평균발아 소요일수도 단축되어, 수분장애시 오차드그라스의 균일한 발아 유도와 발아속도를 개선하는데 효과가 있을 것으로 생각되나, 어떠한 처리에 있어서도 대조구의 무처리구 발아율(79.0%)을 능가하지 못하여 오차드그라스의 발아에 관한 수분장애 요소를 완전히 극복할 수는 없었다.>, $C_{l8:2}$, $C_{l8:1}$, $C_{18:2}$ 등이 주요 지방산으로 조직에 따라 약간씩 다른 경향을 보였다. 그리고 카테킨은 특히 혈청에서 $C_{20:5}$, $C_{22:6}$과 같은 고도불포화지방산의 함량을 유지시키는데 효과적임을 알 수 있었다. 이상의 결과를 미루어 볼 때 과산화된 지질의 섭취는 생체내 대사 이상을 유발할 가능성이 인식되었고 카테킨의 투여는 신선한 어유를 섭취한 경우 뿐만 아니고 이미 과산화된 어유를 섭취한 경우 뿐만 아니고 이미 과산화된 어유를 섭취한 경우에도 생체내에서 과산화 억제작용을 어느 정도 효과적으로 수행하는 것으로 나타나 앞으로 이의 효과적인 활용이 기대된다.다.nsidered to be due to the different food habits and environmental condition of the invertebrates.재강조될 필요가 있다. 이 두 역할개념 들을 교육을 통하여 효과적으로 가르칠

• 한국정밀공학회지
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• 제30권12호
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• pp.1303-1312
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• 2013

We report an ultra-precision lathe designed to machine micron-scale features on a large-area roll mold. The lathe can machine rolls up to 600 mm in diameter and 2,500 mm in length. All axes use hydrostatic oil bearings to exploit the high-precision, stiffness, and damping characteristics. The headstock spindle and rotary tooling table are driven by frameless direct drive motors, while coreless linear motors are used for the two linear axes. Finite element method modeling reveals that the effects of structural deformation on the machining accuracy are less than $1{\mu}m$. The results of thermal testing show that the maximum temperature rise at the spindle outer surface is approximately $0.5^{\circ}C$. Finally, performance evaluations of the error motion, micro-positioning capability, and fine-pitch machining demonstrate that the lathe is capable of producing optical-quality surfaces with micron-scale patterns with feature sizes as small as $20{\mu}m$ on a large-area roll mold.

• 한국의류산업학회지
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• 제23권2호
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• pp.237-246
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• 2021

This study aims to analyze short sleeve cycling tops from three brands for a change in garment fit and pressure depending on the static and cycling postures. To this end, it used a 3D virtual garment system to virtualize the garments. Further, a cross-section of the 3D virtual garment data was obtained, and the space length was measured in the design-X program to prove the objectivity of the 3D virtual garment. The results indicated that three brands had a large space length at the front than the back because of the bent posture in cycling. Therefore, appropriate ease was required for the waist and abdomen. Although there were various cutting lines of the bodice panel by brand, the design of the cutting lines should consider the changes in the surface to reflect the bent posture in cycling. The results of this experiment confirmed that the wrinkles present in the 3D virtual garment were reflected in the cross-section and that the space length was small in the high-stress area, as shown in red. Therefore, it was proven the stress of the 3D virtual garment could be used for 3D virtual garment evaluation.

• 한국환경복원기술학회지
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• 제15권6호
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• pp.79-89
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• 2012

This study was compared to the differences in the habitat, species composition and community structure of revegetation and nature area in Korea. Plant number in plot of revegetation and nature area was 10.3 and 15.0 taxa, respectively, and coverage was 90.6 and 88.1%, respectively. Revegetation and nature area was very heterogeneous, due to low similarity index (0.38) and less common plants. Festuca arundinacea frequency (56.7%) was highest in revegetation area, and Oplismenus undulatifolius frequency (66.7%) was highest in nature area. Plant appearing of revegetation and nature area was 111 and 136 taxa, respectively. Herb appearing of revegetation and nature areas was 93 (83.3%) and 72 (52.9%) taxa, respectively, tree was 18 (16.2%) and 64 (47.1%) taxa, respectively. Plant communities of revegetation area was classified into Lespedeza bicolor, Indigofera amblyantha, Alnus sibirica, Festuca arundinacea, Eragrostis curvula, Miscanthus sinensis, Humulus japonicus, Setaria faberii, Rudbeckia bicolor, Pueraria lobata community. Plant communities of nature area was classified into Pinus densiflora, Quercus aliena, Quercus acutissima, Quercus variabilis, Quercus serrata, Castanea crenata, Pinus rigida, Robinia pseudoacacia, Populus tomentiglandulosa, Phyllostachys bambusoides community. Habitat, species composition and community structure of revegetation and nature area showed a large difference.