• Korean Chemical Engineering Research
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• v.58 no.2
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• pp.286-292
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• 2020

This study presents an angular-based measurement on three-dimensional paper-based analytical devices (3D-PADs) for quantitative detection of albumin without using an image analyzer. We demonstrate a simple quantitative and straightforward approach based on the angle of the discolored area as detection criteria. 3D-PADs are rapidly fabricated by the wax-printing and laminating process. The 3D-PADs are treated with citrate buffer and tetrabromophenol blue to react with albumin in a sample solution. Dropping sample solution into sample pad in the 3D-PAD, fluid flows toward the assay zone laterally and vertically by capillary action. We find that the change of angle of the discolored area correctly reflects the concentration of albumin and is reliable determinant for the measurement of the albumin concentration. It is the first demonstration of angular-based detection as a simple, inexpensive, and equipment-free approach for point-of-care diagnosis.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.28 no.8 s.227
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• pp.921-928
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• 2004

Measurements of local heat/mass transfer coefficients in rotating two-pass ducts are presented. Ducts of three different aspect ratios (W/H), 0.5, 1.0 and 2.0, are employed with a fixed hydraulic diameter ($D_h$) of 26.7 nm. $90^{\circ}$-rib turbulators are attached on the leading and trailing walls symmetrically. The rib height-to-hydraulic diameter ratio ($e/D_h$) is 0.056, and the rib pitch-to-rib height ratio (p/e) is 10. The experimental conditions are the same as those of the previous part of the study. As the rib height-to-duct height ratio (e/H) increases, the core flow is more disturbed and accelerated in the midsections of ribs. Therefore, the obtained data show higher heat/mass transfer in the higher aspect ratio duct. Dean vortices also augment heat/mass transfer in the turn and in the upstream region of the second pass. However, the effect becomes less significant for the higher aspect ratio because the surface area increases in the present geometric condition. The effect of rotation produces heat/mass transfer discrepancy.

• Proceedings of the KSME Conference
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• 2004.11a
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• pp.1104-1109
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• 2004

The present study has been conducted to investigate convective heat/mass transfer inside the cooling passage with bleed holes. The rotating square channel has 40.0 mm hydraulic diameter and the bleed holes on the leading surface of the channel. The hole diameter of bleed hole is 4.5 mm and its spacing (P/d=4.9) is about five times of hole diameter. Mass flow rate through bleed holes is 10% of the main flow rate and rotation number is changed form 0.0 to 0.4. A naphthalene sublimation technique is employed to determine the detailed local heat transfer coefficients using the heat and mass transfer analogy. The cooling performance is influenced by mass flow rate through bleed holes and Coriolis force of rotating channel for fixed reynolds number. The heat transfer is enhanced around holes on the leading surface because of trapping flow by bleeding. However heat transfer on the leading surface is decreased due to Coriolis force.

• The Journal of the Korea institute of electronic communication sciences
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• v.11 no.7
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• pp.685-692
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• 2016

In this paper, we not only take advantage of the SIFT features in banknote recognition, which has robustness to illumination changes, geometric rotation as well as scale changes, but also propose the hierarchical banknote recognition algorithm, which comprised of feature vector extraction from the frame grabbed image of the banknotes, and matching to the prepared data base of multinational banknotes by ANN algorithm. The images of banknote under the developed UV, IR and white illumination are used so as to extract the SIFT features peculiar to each banknotes. These SIFT features are used in recognition of the nationality as well as face value. We confirmed successful function of the proposed algorithm by applying the proposed algorithm to the banknotes of Korean and USD as well as EURO.

• Current Industrial and Technological Trends in Aerospace
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• v.4 no.1
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• pp.34-43
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• 2006

헬기는 비행에 필요한 추력, 모멘트 및 조종력을 회전하는 로터시스템에서 발생시키기 때문에 근본적으로 진동이 많이 생기는 항공기이다. 로터시스템의 회전에 의해 발생되는 진동소스를 제어함으로써 헬기 동체에 전달되는 진동을 감소시키고자 하는 연구들이 지금까지 수많이 진행되었다. 이러한 연구들을 크게 두 가지로 분류하면, 수동적 진동제어 방법과 능동적 진동제어 방법으로 나눌 수 있다. 수동적 진동제어 방법은 그간 오랫동안 연구되어 현재 운용 헬기에 실제적으로 적용되고 있으나 능동적 진동제어 방법은 최근까지 활발한 연구가 진행되고 있는 상태이다. 본 논문의 서론에서는 헬기 진동제어를 위한 일반적인 방법에 대한 개요를 소개하였다. 본문은 로터시스템 진동제어 기술 중 최근까지 연구가 진행되고 있는 능동적 진동제어 방법을 중심으로 기술하였다. 특히 최근 비행시험에 성공하여 거의 실용화 단계에 이르고 있는 PZT를 이용한 Trailing Edge Flap 기술, Active Twist Rotor 등을 중점적으로 소개하였다. 마지막으로 유로콥터 BK117의 ADASYS 로터 시스템 성공사례 및 향후 해결해야 할 기술적 제한사항 등을 간략하게 기술하였다.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.28 no.12
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• pp.1549-1556
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• 2004

We have deigned, fabricated and compared four different types of static chaos microfluid mixers, including the mixers using straight channel flow, microblock-induced alternating whirl flow, microchannel-induced lamination flow, and combined alternating whirl-lamination flow. Among them, the alternating whirl-lamination (AWL-type) mixer, composed of 3-D rotationally arranged microblocks and dividing microchannels fabricated by conventional planar lithography process, is effective to reduce the mixing length over wide flow rate ranges. We characterize the performance of the fabricated mixers, through the flow visualization technique using phenolphthalein solution. We verify that the AWL-type microfluid mixer shows the shortest fluid mixing length of 2.8mm∼5.8mm for the flow rate range of Re=0.26∼26 with the pressure drop lower than 5kPa. Compared to the previous mixers, requiring the mixing lengths of 7∼17mm, the AWL-type microfluid mixer results in the 60% reduction of the mixing lengths. Due to the reduced mixing lengths within reasonable pressure drop ranges, the present micromixers have potentials for use in the miniaturized Micro-Total-Analysis-Systems($\mu$TAS).

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.46 no.1
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• pp.52-58
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• 2018

A Study on the dynamic characteristics of a rotor driven by a tipjet system in hovering condition was carried out. The sectional modeling was performed for the tipjet blade in which the flow path was inserted, and the dynamic characteristics analysis was conducted by modeling the components of the proposed rotor system. The analysis was conducted with respect to the rotational speed and the collective pitch. As a result of the analysis, it was checked that the proposed tipjet rotor did not have aeroelastic instability within the designed operating range. The tipjet test equipment was constructed in order to verify the analysis approach. It was confirmed that the proposed rotor was driven normally by tipjet. The non-rotating eigenmode measurement test and the rotation test were performed, and the validity was proved by comparing the test results and the analysis results.

• Journal of Advanced Marine Engineering and Technology
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• v.39 no.1
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• pp.28-31
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• 2015

Electromotive forces (EMF) are generated by electrical equipment and engine shafting with a number of reasons. The shaft and bearing which is insulated by lubricating oil acts as a condenser, being able to store this EMFs. The electromotive force on the hull and shaft, with very few exceptions, has anode voltage on it. Electrical spark of the anode voltage on the shaft may lead to corrosion. Hence, in order to prevent ship's shaft and propeller corrosion, shaft grounding system are installed and operated. The shaft EMF voltage measurement methods was measured using 24bit 2 channels A/D converter of NI company and Labview software. 1 channel was propeller shaft's voltage and the other was M/E engine rpm gauge. In this paper, the generated electromotive force was analyzed and modeled with result of the analysis. As a result, the main shaft's electromotive force was in direct proportion to the main engine's revolution. However, over the specific R.P.M., it was reduced gradually. In addition, higher electromotive force on the shaft was identified during engine's ahead direction than the astern direction. The generated electromotive force is only minor compared to the shaft grounding system.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.17 no.10
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• pp.898-906
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• 2005

The present study has been conducted to investigate convective heat/mass transfer in the cooling passage with bleed holes. The rotating square channel has 40.0 mm hydraulic diameter and the bleed holes on the leading surface of the channel. The hole diameter of bleed hole is 4.5mm and its spacing is ( p/d:4.9) about five times of hole diameter. Exit mass flow rate through bleed holes is $10\%$ of the main mass flow rate and relation number is changed form 0.0 to 0.4. A naphthalene sublimation technique is employed to determine the detailed local heat transfer coefficients using the heat and mass transfer analogy The cooling performance is influenced by exit mass flow rate through bleed holes and Coriolis force of rotating channel for fixed Reynolds number. The heat transfer on the leading surface is decreased due to Coriolis force. However the total heat transfer is enhanced around holes on the leading surface because of trapping flow by bleeding.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2008.11a
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• pp.424-426
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• 2008

A parametric study was carried out to find the fuel lubrication performance of high speed small rolling element bearings. Both MIL-PRF-7808 turbine oil and JP-8 aircraft fuel were used as the lubricant to compare the operational characteristics. 17 mm inner diameter deep groove ball bearing and 20 mm cylindrical roller bearing were used. A high speed bearing test rig was developed and the testing was done with varying applied load, cooling air temperature, lubricant flow rate, and speed. Fuel caused more cage wear than oil for ball bearing with increasing axial load and rotational speed. The bearing temperature using fuel was lower than that using oil, and this seems to be the result of the high cooling capacity of fuel. According to various tests, the fuel lubrication is applicable for the lubrication on the main shaft bearings of expendable small gas turbines.