• Transactions of the Korean Society of Automotive Engineers
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• v.11 no.6
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• pp.127-133
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• 2003

NSD(No Spin Differential) has been developed fer a military truck. A benchmarking study for USA and Russian NSD has been carried out. Axiomatic approach has been applied for improving the design. A test code for NSB has been developed and applied to the developed sample. In the test results of comparing the developed sample with the USA imported sample, three major characteristics-the noise, mobility and steerability - are in the range of the intended target. A practical process for the evolution design is proposed.

• Transactions of the Korean Society of Automotive Engineers
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• v.13 no.4
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• pp.32-38
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• 2005

Two No Spin Differential(NSD) models were benchmarked for a project of Dual-Use Technology The Axiomatic approach was utilized to evaluate two models and to derive an evolutionary design from the evaluated results. Test methodology is developed and used to evaluate the mobility, steerability, durability and noise of the newly developed sample. The test results of NSD sample on the test methodology are very positive regarding functional performances.

• Tribology and Lubricants
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• v.16 no.6
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• pp.415-424
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• 2000

The use of magnetoresistive (MR) head requires much tighter control of particle contamination in a drive since loose particles on the disk surface will generate thermal asperities (TA). In this study, a spinoff test was performed to investigate the adhesion and removal capability of a particle to disk surface. Numerical simulation was also performed to investigate dominant factor of particle detachment and to support experimental results. It was shown that particles are detached from the disk surface by the moment derived from the centrifugal force and the drag force and that the centrifugal force and capillary force are the dominant force, which determines spin-off of a particle on the disk surface. Removal of particles smaller than several micrometers, which are the main source of TA generation, is extremely difficult since the adhesion forces exceed the centrifugal force. Lubricant types and manufacturing process also influence the particle removal. Lower bonding ratio and lower viscosity of the lubricant will help to increase the removal rate of the particles from the disk surface.

• The Transactions of the Korean Institute of Electrical Engineers C
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• v.49 no.5
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• pp.315-320
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• 2000

This paper presents the fabrication and test of a micropump with an electromagnetic actuator and a pair of aluminum flap valves. The actuator consists of a solenoid coil, a permanent magnet and an actuator diaphragm. The actuator diaphragm is fabricated by the spin coating of silicone rubber. The valve are passive ones and are fabricated by micromachining. The deflection of the fabricated actuator diaphragm is measured with a laser vibrometer. The deflection of the actuator diaphragm is proportional to the input current. The measured deflection of the fabricated diaphragm is $400 \mum$,/TEX> when the input is 118 mApp, and the cut-off frequency is 50 Hz. The maximum flow rate of the fabricated micropump with the electromagnetic actuator is about 5$0 \muell/min$ at 5 Hz when the input current and the duty ratio of the square was are 118 mApp and 50%, respectively.

• Journal of the Korean Magnetics Society
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• v.8 no.6
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• pp.362-368
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• 1998

The magnetic properties, thermal stability and anti-corrosion properties of $Cr_86Al_14$ spin valves multilayers were studied. It was found that the magnetic properties of $Cr_86Al_14$ spin valves depend on the thickness of antiferromagnetic, ferromagnetic and non-ferromagnetic layers. Exchange coupled field ($H_{ex}$) and magnetoresistance ratio (%) showed the largest value of 20 Oe, 2 % in $glass/Cr_{86}Al_{14}(600 $\AA$)/Ni_{81}Fe_{19}(50$\AA$)/Cu(40 $\AA$)/Ni_{81}Fe_{19}(40 $\AA$)$ spin valves. The $H_{ex}$ MR ratios (%) of CrAl and FeMn spin valves were decreased with increasing annealing temperatures and were lost at 150 $^{\circ}C$, 250 $^{\circ}C$ respectively. Based on these result, it was elucidated that CrAl is more thermally stable than FeMn. It was also shown that there was no change of $H_{ex}$ MR ratios in CrAl, while FeMn was changed and lost 15 days later in corrosion resistance test under 35 $^{\circ}C$, 90 % humidity condition. FeMn was found to be pitted and peeled off 15 days later by SEM micrographic analysis.

• The Bulletin of The Korean Astronomical Society
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• v.41 no.1
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• pp.54.2-54.2
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• 2016

Korea Microlensing Telescope Network (KMTNet) is the first optical survey system of its kind in a way that three KMTNet observatories are longitudinally well-separated, and thus have the benefit of 24-hour continuous monitoring of the southern sky. The wide-field and round-the-clock operation capabilities of this network facility are ideal for survey and the physical characterization of small Solar System bodies. We obtain their orbits, absolute magnitudes (H), three dimensional shape models, spin periods and spin states, activity levels based on the time-series broadband photometry. Their approximate surface mineralogy is also identified using colors and band slopes. The automated observation scheduler, the data pipeline, the dedicated computing facility, related research activity and the team members are collectively called 'DEEP-South' (DEep Ecliptic Patrol of Southern sky). DEEP-South observation is being made during the off-season for exoplanet search, yet part of the telescope time is shared in the period between when the Galactic bulge rises early in the morning and sets early in the evening. We present here the observation mode, strategy, software, test runs, early results, and the future plan of DEEP-South.

• Journal of Industrial and Engineering Chemistry
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• v.68
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• pp.399-405
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• 2018

We report the fabrication of organic field-effect transistors (OFETs) via spray coating of electrochemically exfoliated graphene (EEG) and conducting polymer hybrid as electrodes. To reduce the roughness and sheet resistance of the EEG electrodes, subsequent coating of conducting polymer (poly(3,4-ethylenedioxythiophene)-poly(styrenesulfonate) (PEDOT:PSS)) and acid treatment was performed. After that, active channel layer was developed by spin coating of semiconducting poly(3-hexylthiophene) on the hybrid electrodes to define the bottom gate bottom contact configuration. The OFET devices with the EEG/PEDOT:PSS hybrid electrodes showed a reasonable electrical performances (field effect mobility = $0.15cm^2V^{-1}\;s^{-1}$, on/off current ratio = $10^2$, and threshold voltage = -1.57V). Furthermore, the flexible OFET devices based on the Polydimethlsiloxane (PDMS) substrate and ion gel dielectric layer exhibited higher electrical performances (field effect mobility = $6.32cm^2V^{-1}\;s^{-1}$, on/off current ratio = $10^3$, and threshold voltage = -1.06V) and excellent electrical stability until 1000 cycles of bending test, which means that the hybrid electrode is applicable to various organic electronic devices, such as flexible OFETs, supercapacitors, organic sensors, and actuators.

• Korean Journal of Radiology
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• v.2 no.4
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• pp.210-215
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• 2001

Objective: To investigate the efficacy of gadobenate dimeglumine (GdBOPTA) enhanced MR imaging for the detection of liver lesions in patients with primary malignant hepatic neoplasms. Materials and Methods: Thirty-one patients with histologically proven primary malignancy of the liver were evaluated before and after administration of GdBOPTA at dose 0.05 or 0.10 mmol/kg. T1-weighted spin echo (T1W-SE) and gradient echo (T1W-GRE) images were evaluated for lesion number, location, size and confidence by three off-site independent reviewers and the findings were compared to reference standard imaging (intraoperative ultrasound, computed tomography during arterial portography or lipiodol computed tomography). Results were analyzed for significance using a two-sided McNemar's test. Results: More lesions were identified on Gd-BOPTA enhanced images than on unenhanced images and there was no significant difference in lesion detection between either concentration. The largest benefit was in detection of lesions under 1 cm in size (7 to 21, 9 to 15, 16 to 18 for reviewers A, B, C respectively). In 68% of the patients with more than one lesion, Gd-BOPTA increased the number of lesions detected. Conclusion: Liver MR imaging after Gd-BOPTA increases the detection of liver lesions in patients with primary malignant hepatic neoplasm.