• Korean Journal of Computational Design and Engineering
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• v.15 no.6
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• pp.460-466
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• 2010

These days, it is getting important to have more chances to visit natural environment for the wellbeing life. The advancement of digital technologies allows us to get useful information regardless of time and location. In this paper, we investigate a way of improving user experience in the natural green environment using the digital technologies. This paper proposes a system called Green-UX-Story which supports users to create and share their story through the online and offline green experience. The system consists of two main systems: the "Story-Field" and the "Story-Tree". The Story-Field consists of a certain number of the Story-Trees allocated to a certain green site. In the Story-Field, users can see the Story-Trees that are owned by other users and share their stories. The Story-Tree contains the user-story in each branch and green information that are captured by the user on the web. The Story-Tree is generated using the L-system algorithm as the user adds stories. The main purpose of the system is to enable users to write their green stories from the both online and offline experiences. This paper describes the system configuration and the user scenario of the Green-UX-story.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.27 no.9
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• pp.1607-1613
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• 2003

An experimental method to measure Q-parameter in-situ is described. The basic idea comes from the fact that the side necking near a crack tip indicates the loss of stress triaxiality, which can be scaled by Q. From the out-of-plane displacement and the in-plane strain near the surface of side necking, stress field averaged through the thickness is calculated and then Q is determined from the difference between the stress field and the HRR field corresponding to the identical J-integral. To prove the validity, three-dimensional finite element analysis has been performed for a CT configuration with side-groove. Q-value which was calculated directly from the near-tip stress field is compared with that determined by simulating the experimental procedure according to the proposed method, that is, the Q-value determined from the lateral displacement and the in-plane strain. In addition, the effect of location where the displacement and strain are measured is explored.

• Journal of the Korean Society of Systems Engineering
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• v.15 no.1
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• pp.16-24
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• 2019

In this study, an improved method of setting the RAM goals for surveillance system using OMS/MP and field operations data of similar systems is suggested and a case study of surveillance system A is given. Newly suggested methods for setting the RAM goals consist of the procedures such as On/Off time analysis of configuration equipment based on OMS/MP, field operations data analysis of similar systems, adjustment of preventive maintenance time, the number of corrective maintenances, and TALDT in wartime, introducing new subsystem to reliability structure of surveillance system, and reflecting expert's opinion. A case study of surveillance system A shows that newly suggested method in this study for setting the RAM goals is reasonably acceptable and practically applicable to other similar systems.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.68 no.3
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• pp.471-479
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• 2019

This research proposes a indoor magnetic map matching algorithm that improves the position accuracy by employing multiple magnetic sensors and probabilistic candidate weighting function. Since the magnetic field is easily distorted by the surrounding environment, the distorted magnetic field can be used for position mapping, and multiple sensor configuration is useful to improve mapping accuracy. Nevertheless, the position error is likely to increase because the external magnetic disturbances have repeated pattern in indoor environment and several points have similar magnetic field distortion characteristics. Those errors cause large position error, which reduces the accuracy of the position detection. In order to solve this problem, we propose a method to reduce the error using multiple sensors and likelihood boundaries that uses human walking characteristics. Also, to reduce the maximum position error, we propose an algorithm that weights according to their importance. We performed indoor walking tests to evaluate the performance of the algorithm and analyzed the position detection error rate and maximum distance error. From the results we can confirm that the accuracy of position detection is greatly improved.

• Journal of Sensor Science and Technology
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• v.32 no.4
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• pp.232-237
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• 2023

This paper presents a system for estimating the position of a magnet using a magnetic sensor. An algorithm is presented to analyze the waveform and output voltage values of the magnetic field generated at each position when the magnet moves and to estimate the position of the magnet based on the analyzed data. Here, the magnet is sufficiently small to be inserted into a blood vessel and has a micro-magnetic field of hundreds of nanoteslas owing to the small size and shape of the guide wire. In this study, a highly sensitive magneto-impedance (MI) sensor was used to detect these micro-magnetic fields. Nine MI sensors were arranged in a 3×3 configuration to detect a magnetic field that changes according to the position of the magnet through the MI sensor, and the voltage value output was polynomially regressed to specify a position value for each voltage value. The accuracy was confirmed by comparing the actual position value with the estimated position value by expanding it from a 1D straight line to a 3D space. Additionally, we could estimate the position of the magnet within a 3% error.

• Journal of the Korea Society for Simulation
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• v.28 no.2
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• pp.81-88
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• 2019

Since the AESA radar scans and tracks a distant targets or ground, it requires a test field which meets far-field condition before flight test. In order to test beam foaming, targeting, and availability from cluttering and jamming, it is general to build a outdoor roof-lab test site at tens of meters high. However, the site is affected by surrounding terrain, weather, and noise wave and is also requires time, space, and a lot of costs. In order to solve this problem, theoretical near-field beam foaming method has proposed. However, it requires modification of associated hardware in order to construct near-field test configuration. In this paper, we propose near-field beam foaming method which use single LUT in order to calibrate the variation of TRM(transmit-receive module) which consists AESA radar without modification of associated hardware and software. It requires less costs than far-field test and multiple LUT based near-field test, nevertheless it can derives similar experimental results.

• Proceedings of the KSME Conference
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• 2007.05b
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• pp.2378-2383
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• 2007

Direct Numerical Simulation was carried out to predict mass transfer in turbulent flow around a rotating stepped cylinder. This investigation is a follow-up study of Nesic et al. [Corrosion, Vol. 56, No. 10, pp. 1005 - 1014] The original motivation of this work stemmed from the efforts to design a simple device which can generate flows of high turbulence intensity at low cost for corrosion researchers. Two cases were considered; Sc=1 and 10 both at Re=335. Here, Sc and Re stand for Schmidt number and Reynolds number, respectively, based on the step height and the surface speed of the cylinder upstream the step. Main focus was placed on the correlation between turbulent fluctuation and concentration field. The spatio-temporal evolution of concentration field is discussed. The numerical results are qualitatively compared with those of the experiment conducted with the same flow configuration.

• Journal of computational fluids engineering
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• v.16 no.2
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• pp.56-61
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• 2011

Numerical study is conducted to design the high temperature heat exchanger of Stirling engine by using the commercial CFD solver, FLUENT. The Fin-tube type of heat exchanger is designed as a reference model by considering the type of engine which is ${\beta}$-configuration. To find the optimal design of heat exchanger in heat transfer capacity numerical calculation is conducted by changing the shape, the number, and material of reference model in three-dimensional combustion field. Adjusted one-way constant velocity of working fluid that is helium is considered as the representative velocity of oscillating flow. The optimal design of heat exchanger considering the heat transfer capability is suggested by using the calculation results.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.15 no.11
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• pp.2301-2306
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• 2011

Current general-purpose electromagnetic field simulators have been widespread applied, and is being used to electromagnetic problems such as antenna design, EMC design, measurement, and microwave device design, etc. This paper is to solve various electromagnetic problems in X-band region for utilizing multi-core-based PC available network resources more efficiently. The electromagnetic field simulator based on TCP / IP-based network topology, configuration, and its framework design is proposed and its availability is examined.

• Bulletin of the Korean Chemical Society
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• v.35 no.5
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• pp.1491-1494
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• 2014

High-crystallinity poly(3-hexylthiophene) (P3HT) thin films were prepared by aging the precursor solutions, prepared using a good solvent, chloroform, at low temperatures prior to spin-casting. Lower solution temperatures significantly improved the molecular ordering in the spin-cast P3HT films and, therefore, the electrical properties of field-effect transistors prepared using these films. Solution cooling enhanced the electrical properties by shifting the P3HT configuration equilibrium away from random coils and toward more ordered aggregates. At room temperature, the P3HT molecules were completely solvated in chloroform and adopted a random coil conformation. Upon cooling, however, the chloroform poorly solvated the P3HT molecules, favoring the formation of ordered P3HT aggregates, which then yielded more highly crystalline molecular ordering in the P3HT thin films produced from the solution.