• Physical Therapy Korea
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• v.19 no.3
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• pp.61-71
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• 2012

In daily activities, people often perform two or more tasks simultaneously. This is referred to as dual-tasking or multi-tasking. The purpose of this study was to examine the effects of performing dual tasks while using a mobile phone on static and dynamic postural stability. Twenty-four subjects were asked to stand on a force plate and then instructed to perform a balance task only (BT), a balance task while listening to music (BTL), a balance task while talking on the mobile phone (BTT), and a balance task while sending text messages (BTS). We used the BioRescue$^{(R)}$ to measure postural sway and limit of stability for static and dynamic postural stability. Also the star excursion balance test (SEBT) was used to measure dynamic postural stability. A one-way ANOVA with repeated measures was used to compare the effects of the BT, BTL, BTT, and BTS. The Bonferroni's post hoc test was used to determine the differences among four tasks. Carrying out the BTS significantly decreased the limit of stability compared with carrying out the BT, BTL, and BTT (p<.05). In limit of stability, total surface area of BTT was more significantly decreased than that of BT and total surface area of BTS was more decreased than that of BT, BTL and BTT (p<.05). In the SEBT, the BTS displayed significantly smaller reach distance values compared with the BT or BTL (p<.05). These findings suggest that performing the balance task while sending text message on the mobile phone decreases dynamic postural stability, whereas performing the same task while listening to music using the mobile phone does not. Therefore, it requires more attention to maintain dynamic balance while sending text messages.

• Transactions of the Korean Society of Automotive Engineers
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• v.22 no.3
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• pp.210-219
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• 2014

The MPI dual injection engine can enhance the fuel efficiency and engine power. By using one injector per one intake port, MPI dual injection engine has an excellent fuel atomization and targeting injection. As the basic research for the MPI Dual injection engine design, this research was investigated in order to understand the characteristic of the in-cylinder flow and fuel behavior according to engine temperature condition and the fuel type in the MPI dual injection engines. The 3D unsteady CFD simulation for the MPI Dual injection engine was performed using STAR-CD. The engine operating condition was 2,000 rpm/WOT. The parameters for this study were fuel types, fuel temperatures and wall temperatures. As a result, the intake air amount, evaporated fuel in the cylinder and the fuel film on the wall were presented according to parameters that depend on the fuel properties and engine wall temperature. Also, the results were influenced by in-cylinder flow such as the intake flow, back flow and so on.

• Transactions of the Korean Society of Automotive Engineers
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• v.23 no.2
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• pp.221-229
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• 2015

The PFI dual injection engine using one injector per an intake port was developed for solving the DISI engine cost problem. Excellent fuel atomization and targeting of the PFI dual injection engine made enhancement on the fuel efficiency and engine power. In order to develop a PFI dual injection engine, characteristics of the in-cylinder flow and fuel behavior with respect to fuel injection angle and cone angle of the PFI dual injection engine was investigated. Numerical calculation was conducted to analyze 3D unsteady in-cylinder flow and fuel behavior using STAR-CD. The engine operating condition was 2,000rpm at WOT. As a result, the amount of intake air, evaporated fuel and fuel film according to injection angle and cone angle were presented. The results were influenced by interaction between injected fuel and intake port wall.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2002.11b
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• pp.57-61
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• 2002

In this paper, the structural and thermal integrity of a Dual Mass Flywheel (DMFW) being developed by HMC is assessed with conventional FEM code. Some parts were modified in order to satisfy the SAE and RICARDO's assessment limit, and we found that FEM was valuable tools in developing new DMFW system.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2002.11a
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• pp.313.2-313
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• 2002

본 논문은 현대자동차에서 개발중인 이중질량플라이휠(DMFW)의 구조적, 열적 특성을 FEM code를 사용하여 평가하였다. DMFW의 몇몇 단품들은 SAE와 RICARDO에서 제시하는 평가기준을 만족시키기 위해서 일부 수정되었으며, 새로운 DMFW 시스템을 개발하는데 있어서 FEM을 사용한 방법은 매우 유용함을 알 수 있다.

• Journal of Sensor Science and Technology
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• v.29 no.4
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• pp.270-274
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• 2020

In this study, a read-out integrated circuit (ROIC) that can be applied to a colorimetry-based optical sensor for analyzing total phosphorus and total nitrogen was developed and characterized. The proposed ROIC minimizes the effect on temperature fluctuation, improves sensitivity, and extends the dynamic range by utilizing a dual optical path and feedback control circuit. Using a dual optical path makes it possible to calibrate the output signal of the optical sensor automatically, along with the temperature fluctuation. The calibrated voltage is fed back into the measurement stage; thus, the output current of the measurement is adaptively controlled. As a result, the sensitivity and dynamic range of the proposed ROIC are improved. Finally, a total-phosphorus analysis was conducted by utilizing the ROIC. The ROIC was found to operate stably over a wide temperature range.

• Transactions of the Korean Society of Automotive Engineers
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• v.21 no.5
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• pp.15-24
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• 2013

Numerical studies were conducted to investigate the internal flow field and combustion characteristics of DISI engine with methanol blended in gasoline. Dual injection was applied and the characteristics were compared to single injection strategy. The amount of the fuel injection was corresponded to air-fuel ratio of each fuel for complete combustion. The preforming model in this study, software STAR-CD was employed for both modeling and solving. The operating speed condition were at 4000 rpm/WOT (Wide open throttle) where the engine was fully warmed. The results of single injection with M28 showed that the uniformity, equivalence ratio, in-cylinder pressure and temperature increased comparing to gasoline (M0). When dual injection was applied, there was no significant change in uniformity and equivalence ratio but the in-cylinder pressure and temperature increased. When M28 fuel and single injection was applied, the CO (Carbon monoxide) and NO (Nitrogen oxides) emission inside the combustion chamber increased approximately 36%, 9% comparing with benchmarking case in cylinder prior to TWC (Three Way Catalytic converter). When dual stage injection was applied, both CO and NO emission amount increased.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.33 no.3
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• pp.93-98
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• 2005

STSAT-2 will be launched on December 2007 by the first Korean launch vehicle KSLV-1, and its one of the main instruments is DREAM (Dual Channel Radio Frequency and Environment Atmosphere Monitoring) which detects a signal for atmosphere from the Earth by using micro-wave signal. The STSAT-2 has many units for technology demonstration such as FDSS (Fine Digital Sun Sensor) and DHST (Dual Head Star Tracker) including PPT (Pulsed Plasma Thruster) for attitude control and momentum dumping in the space. In this paper, the power budget analysis for STSAT-2 will be studied and provided for supporting the whole mission life time during the mission of its spacecraft.

• The Transactions of the Korea Information Processing Society
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• v.2 no.1
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• pp.95-105
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• 1995

An appendix to the MAP 3.0 specification notes that there are primary advantages to use of fiber optics : noise immunity, ability to run in difficult electrical environments, safety and high data rates. All of these may be quite useful in various manufacturing environments. In this paper, we study on construction schmes for a fiber-based 802.4 MAP system including the use of both bus and star topologies. We suggest passive star network and FDDI network for manufacturing environment. And then, we propose the FDDI protocol including the use a dual ring topology running at 100 Mbps to physical and datalink layer of MAT specification and analysis it's protocol and topology for abilities in manufacturing environments, We evaluate about applications service, time-critical processing and topology of two models in manufacturing environment.

• The Bulletin of The Korean Astronomical Society
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• v.45 no.1
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• pp.38.2-38.2
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• 2020

Horizon Run 5 (HR5) is a cosmological hydrodynamical simulation which captures the properties of the Universe on a Gpc scale while achieving a resolution of 1 kpc. This enormous dynamic range allows us to simultaneously capture the physics of the cosmic web on very large scales and account for the formation and evolution of dwarf galaxies on much smaller scales. Inside the simulation box. we zoom-in on a high-resolution cuboid region with a volume of 1049 × 114 × 114 Mpc3. The subgrid physics chosen to model galaxy formation includes radiative heating/cooling, reionization, star formation, supernova feedback, chemical evolution tracking the enrichment of oxygen and iron, the growth of supermassive black holes and feedback from active galactic nuclei (AGN) in the form of a dual jet-heating mode. For this simulation we implemented a hybrid MPI-OpenMP version of the RAMSES code, specifically targeted for modern many-core many thread parallel architectures. For the post-processing, we extended the Friends-of-Friend (FoF) algorithm and developed a new galaxy finder to analyse the large outputs of HR5. The simulation successfully reproduces many observations, such as the cosmic star formation history, connectivity of galaxy distribution and stellar mass functions. The simulation also indicates that hydrodynamical effects on small scales impact galaxy clustering up to very large scales near and beyond the baryonic acoustic oscillation (BAO) scale. Hence, caution should be taken when using that scale as a cosmic standard ruler: one needs to carefully understand the corresponding biases. The simulation is expected to be an invaluable asset for the interpretation of upcoming deep surveys of the Universe.