• 한국정밀공학회지
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• 제33권10호
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• pp.851-856
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• 2016

Planetary gear systems have several advantages over traditional gearboxes with parallel axis gear shafts. The planetary gearbox arrangement also creates greater stability due to the even distribution of mass and increased rotational stiffness. However, gears in planetary gear systems occasionally have a short-life due to wear and breakage by repetitive load during operation time. In this study, we evaluated variables of the strength design for each part and conducted structural analysis of seven cases of the planetary gear system. The result of structural analysis was applied to shape optimization method and obtaining the weight lightening designed value. Subsequently, the planetary gear system was performed to ensure the durability of gears during operation time with miner's rule.

• Biomolecules & Therapeutics
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• 제21권5호
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• pp.343-348
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• 2013

We investigated the inhibitory effects of hesperidin on melanogenesis. To find melanosome transport inhibitor from natural products, we collected the structural information of natural products from Korea Food and Drug Administration (KFDA) and performed pharmacophore-based in silico screening for Rab27A and melanophilin (MLPH). Hesperidin did not inhibit melanin production in B16F10 murine melanoma cells stimulated with ${\alpha}$-melanocyte stimulating hormone (${\alpha}$-MSH), and also did not affect the catalytic activity of tyrosinase. But, hesperidin inhibited melanosome transport in melanocyte and showed skin lightening effect in pigmented reconstructed epidermis model. Therefore, we suggest that hesperidin is a useful inhibitor of melanosome transport and it might be applied to whitening agent.

• Journal of Biosystems Engineering
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• 제23권3호
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• pp.259-270
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• 1998

An automatic seedling transplanter, employed an innovative plug-seedling feeder was developed by improving the problems of conversational feeding and transplanting mechanisms. With conventional methods, missing and damage rates of seedling were high for long seedlings over 20cm and also breaking seed-bed was frequently observed. Thus, a pushout-bucket slide-hopper type trandsplanter was devised and tested. Test results of picking and transferring accuracies of the developed transplanter are as follows : A prototype transplanter performed with 1.5% of missing rate. The deviations of horizontal feed ranged from -0.3mm to 2.8mm and averaged 0.673mm for the 128-hoe test tray : and ranged from -lmm to ＋3mm and averaged 0.785mm for the 200-hole test tray. The deviations could decrease with precise manufacturing and lightening the mechanism. The maximum and deviations of vertical feed were -2.3mm and + 1mm, respectively, for the 128-hole test tray ; and were ＋3mm and ＋2.5mm, respectively, for the 200-hole test tray. The missing rate, seeding bruise rate and seed-bed damage rate were esitmate to be 1.3％, 0.4% and 3.5％, respectively, with the developed automatic transplanter.

• 전기학회논문지P
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• 제60권2호
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• pp.91-93
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• 2011

This paper is presented for the performance of the Fluid Dynamic Bearing(FDB) by the groove design and the tooling condition. Recently, spindle motors which require smaller size, lower sound noise, lower vibration, and higher speed of the rotation have been placed in high value-added products including Digital Lightening Processors(DLP), Hard Disk Drives(HDD), and ODDs. The spindle motors using the sintered porous metal bearing have higher vibration and acoustic noise by dry contact and large tolerance of the bearing parts. The Fluid Dynamic Bearing (FDB) with grooves is appropriate for spindle motors adequate in regards to mechanical vibration and acoustic noise. The paper shows the performance comparisons of between sintered porous metal bearing and FDB, and each FDBs according to the tooling deviations of grooves by the Finite Element Analysis(FEA) of the mechanical field. This paper shows the methods to make the grooves, the groove's depth, and the prototype of the motor with the fluid dynamic bearing. The performance characteristics of the grooves with the FDB are verified by the experimental results.

• 한국응용과학기술학회지
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• 제26권2호
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• pp.171-178
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• 2009

A comparative analysis of the hindered amine light stabilizers (HALS) and UV abosrber (UVA) and their respective photostabilizing effect on wood plastic composites (WPCs) are reported in this study. The influence of accelerated weathering on the mechanical properties of the composites and the microscopic morphology of a degraded layer on the cross section and the surface were studied. UV absorbers were more efficient at preventing composite lightening than was UV stabilizer. The amount of whitening decreased with the increase of photostabilizers. With the addition of a UV absorber (Tinuvin360), the tensile modulus and strength of the composites increased slightly. However, the addition of a light stabilizer (Tinuvin770) and a UV absorber decreased the tensile modulus and strength of the composites. After 250 and 500 hr exposure, tensile modulus and strength of the un stabilized and stabilized composites decreased. The tensile strength of UV absorber (Chimassorb81)-stabilized composites was significantly greater than that of control and light stabilizer (Tinuvin770)- and UV absorber (Tinuvin360)-stabilized composites. UV absorber-stabilized samples showed less whitening and photodegradation than control and light stabilizer-stabilized samples.

• 한국통신학회논문지
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• 제35권2B호
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• pp.225-231
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• 2010

본 논문에서는 유헬스(u-Health) 서비스를 제공하는 센서 네트워크 시스템을 제안한다. 본 시스템은 거주자의 생체 정보를 수집하고 응급 상황을 자동으로 판단한다. LEID(Lighting Embedded Information Device)는 센서 네트워크에 이용 되는 장치로서 생활공간에 필요 불가결한 조명 기기에 센서 네트워크 기술을 접목시킨 장치이다. 본 논문에서 제안한 유헬스 시스템의 실용성 검증을 위해 국민대학교에 위치한 지능형 홈 센터에 설치하였고 실생활을 가정하여 시험하였다. 본 논문에서 제안한 유헬스 시스템은 지속적인 관리가 필요한 환자가 있는 기관에 사용될 수 있다.

• 대한화장품학회지
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• 제28권3호
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• pp.63-90
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• 2002

멜라닌의 정량은 인체에서 화장품의 미백효과를 평가하기 위한 가장 좋은 방법이지만 인체의 멜라닌 측정을 위한 높은 정확성을 가진 non-invasive방법은 아직 확립되지 않은 실정이다. 피부에서 화장품의 미백효과는 피부색의 밝기로 나타낼 수 있으므로 화장품의 미백효력 평가를 위한 재현성있는 방법으로는 피부색측정을 하는 것이 합리적이다 이에 colorimeter, mexameter와 전문가의 육안평가같은 여러 기기나 분석법이 사용되었다. 이 강연에서는 미백효과에 대한 평가를 위한 다양한 평가방법에 대해 자세히 보고하고 각 방법에 대하여 토의하게 될 것이다 그리고 간단히 임상시험에 대한 결과를 보고하고 마지막으로 melanocyte를 정량하는 새로운 non-invasive방법에 대한 model을 제시하려고 한다.

• 대한기계학회논문집A
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• 제24권5호
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• pp.1103-1114
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• 2000

Recent attempt to enhance the safety against collision reshaped the simple shell structures into the integrated complex shell structures. Moreover, due to various regulations continuously tightened for environment protection, weight reduction of automobiles becomes an increasingly important issue. Auto parts lightening is mainly accomplished by more reasonable design, adoption of lighter materials and miniaturization of the auto bodies. Focusing on the locally enhanced design approach among the above three ways, we here attempt to develop a patching optimization method, and also to determine the thicknesses of an integrated shell structure, both bringing a specified amount of stress relaxation. We first select a cross member as a patching optimization model. Based on the finite element stress calculations, we relieve the stress of cross member by patching in two ways-nonuniform thickness patching and optimized uniform thickness patching, the latter of which is more effective in a practical point of view for the preset amount of stress relaxation. Selecting a box type subframe as another finite element analysis model, we then determine the thickness of each part by axiomatic design approach for a preset amount of stress relaxation. The patching methodology and the axiomatic approach adopted in this work can be applied to the other complex shell structures such as center member and lower control arm.

• 동력기계공학회지
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• 제17권1호
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• pp.97-103
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• 2013

Press machine has advantages over other manufacturing machine which can produce large quantities of products in short time so it is widely used in lots of industrial sectors. To obtain the vehicle's weight lightening and rigidity of the body-frame by applying 'Hot stamping' technique is increasing in the automotive field. In this paper, to improve the irregular vibration arose by 800Ton hot stamping press, the research was continued. Bed, slide and main frame are the key part of working precision, so perform structural analysis was conducted, and based on the analyzing results, structural changes were done on the parts where structural deformation occurred.

• 한국태양에너지학회:학술대회논문집
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• 한국태양에너지학회 2012년도 춘계학술발표대회 논문집
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• pp.410-413
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• 2012

A traditional fabrication method is very difficult to make small robots using embedded sensors, actuators and connectors. Fortunately, Shape Deposition Manufacturing can provide an alternative method, and it has many benefits. Firstly, the weight of robot can be lighter, as it can be consisted of composite materials. Secondly, SDM can make simple robot structures because this approach does not need to use connectors and fasteners. Lastly, SDM gives stiffness and flexibility at the specific parts. Therefore, in this paper, we present a design of 3 segment legs organized by SDM, what the SDM approach is, and compare SDM method with 3 segment prototype legs which uses a traditional approach and made by DGIST.