• Journal of the Institute of Electronics Engineers of Korea SD
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• v.37 no.7
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• pp.36-42
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• 2000

Some polarization characteristics of reflection type photopolymer are investigated. Photopolymer on a Mylar substrate alters an incoming linearly polarized laser beam to an elliptical polarization. Due to the rotation of the polarization, the recording gratings show different diffraction efficiencies. The rotation angle is of order of 10-50% for the tested samples. It is found that the polymer layer does not changes the polarization direction but the Mylar substrate alone distorts the incoming polarization to a comparable degree. As align the polarization states of photopolymers to be parallel with a laser using a He-Ne laser(633nm), which is not sensitive to that material, it was possible to make high diffraction efficiency gratings.

• Transactions of the Korean Society of Mechanical Engineers
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• v.16 no.9
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• pp.1711-1721
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• 1992

A nonlinear dissipative dynamical system can often have multiple attractors. In this case, it is important to study the global behavior of the system by determining the global domain of attraction of each attractor. In this paper we study the global behavior of a forced beam with two mode interaction. The governing equation of motion is reduced to two second-order nonlinear nonautonomous ordinary differential equations. When .omega. /=3.omega.$_{1}$ and .ohm.=.omega $_{1}$, the system can have two asymptotically stable steady-state periodic solutions, where .omega./ sub 1/, .omega.$_{2}$ and .ohm. denote natural frequencies of the first and second modes and the excitation frequency, respectively. Both solutions have the same period as the excitation period. Therefore each of them shows up as a period-1 solution in Poincare map. We show how interpolated mapping method can be used to determine the two four-dimensional domains of attraction of the two solutions in a very effective way. The results are compared with the ones obtained by direct numerical integration.

• Proceedings of the Korea Information Processing Society Conference
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• 2012.11a
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• pp.1311-1314
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• 2012

최근에는 LED 조명으로 인해 조명 제어의 유연성이 높아짐에 따라 가정이나 사무공간에서 해당 공간의 목표 조도를 설정하고 현재 내부조도의 상황에 따라 자동으로 조명을 디밍하는 형태로 연구가 이루어지고 있다. 그러나 이러한 제어방식이 현재 주택용 요금제도로 운영 중인 고정요금제에서는 에너지 비용을 감소시키나, 스마트그리드에서 운영될 RTP(Real Time Pricing)에서는 요금 단계에 따라 오히려 에너지 비용이 증가될 수 있다. 이에 본 논문은 실시간 요금 단계에 따라 LED 조명의 목표 조도를 가변적으로 변화시켜 조명 에너지 비용을 최소화하고 사용자의 작업에 적합한 상황별 조도를 자동으로 제어하여 작업자에게 편리함을 제공하고자 한다. 이때 요금 단계에 따른 상황별 최저 및 최고 조도기준은 KSA 3011 및 IES를 참조하며, 최소한의 조명 에너지 사용을 위해 외부 광량을 최대한 활용하여 현재의 시간에 따라 블라인드의 Open/Close를 자동으로 서비스한다. 사용자의 상황은 PIR, Electric Powermeter, Piezoelectric 센서로부터 사용자의 위치, 가전기기 사용 유무, 착석 여부 등을 파악하고, RTP 요금에 따라 하루동안의 조명에 사용된 전력요금을 시뮬레이션한다.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.36 no.6
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• pp.625-632
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• 2012

The objective of this paper is to demonstrate the cathode channel flooding effects at different stoichiometries in proton exchange membrane (PEM) fuel cells by using visualization techniques. The phenomena of liquid water formation and removal caused by current variations were also examined experimentally. Tests were conducted at cathode stoichiometries of 1.5 and 2.0, and the anode stoichiometry was fixed at 1.5. It is found that at an air-side stoichiometry of 2.0, liquid water begins to form and the flooding occurs faster than at an air-side stoichiometry of 1.5. Also, when the air-side stoichiometry of 1.5 is maintained, the dry-out phenomena is observed in the dry-out area 7.8 A following the field of flooding. Thus, a stoichiometry of 1.5 produced better performance in terms of membrane electrode assembly (MEA) durability and hydrogen ion conductivity than did a stoichiometry of 2.0, in which dry-out occurs beyond 8A.

• Journal of the Korean Chemical Society
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• v.40 no.8
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• pp.542-548
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• 1996

Electrodes modified with threonine, methionine and serine as ligands, which are incorporated by ion exchange into a polycationic film of electropolymerized $[Ru(v-bpy)_3]^{2+}$, have been employed in the determination of mercury in solution. The redox response of the surface-immobilized mercury/ligand complex was used as the analytical signal. When the polymeric film was electropolymerized, the supporting electrolytes were TBAP and $KPF_6$ to compare the morphology and anodic stripping of resulted polymer electrodes. At the case of the latter, the film had high porosity to give an easy incorporation of dopant anions into polymeric film matrix and a high sensitivity in determination of mercury ion. Especially, this polymer modified electrode exhibited possibility of multiple use in mercury determination over ten times. In all cases, calibration curves which were plotted by log of the surface coverage-normalized redox response vs. log[Hg] exhibited an excellent correlation (r=0.99) for mercury concentrations ranging from 1.0{\times}10^{-8}{\sim}1.0{\times}10^{-2}M$. At these curves relative standard deviation was 5∼8% and saturation response was not observed at high concentration region. Serine of the employed ligands had the best sensitivity in analytical application, which had greater stability constant in forming a complex with mercury than others as $pK_{Hg}=8.54$. The formation constants of threonine and methionine were respectively 7.04 and 7.80.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.17 no.10
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• pp.548-553
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• 2016

This study analyzed the effect of the operation system of human resource management. First, the primary operating direction of the goal, talent selection system, and personnel management personnel management affected almost all the performance variables. More than one primary goal of personnel management in the loyalty inspired workers more than the fixed labor costs, and external recruitment of short-term hiring favored internal training scheme for long-term employment, employee training, and development in the long term more than short-term performance improvement the more weight to quality and innovation in the productivity of labor, product and services, employee-driven innovation, reduce turnover, had a positive impact on labor relations. On the other hand, the primary goal of personnel management and personnel selection methods had a positive impact on financial performance. Personnel management operating direction did not significantly affect the financial results. Second, the main type of employee utilization affected the quality of products and services, and labor relations. Trying to take advantage of temporary workers more than regular workers had a positive impact on the quality of products and services, and labor relations. Third, the operating unit of Personnel Management had an impact on the degree of innovation of products and services. Both personal achievements and the performance of the operating units had a positive impact on the degree of innovation of products and services, more than teamwork and personnel management. This study provided practical implications for verifying the effect of detailed characteristics of human resource management on financial/non-financial business performance.

• Journal of the Institute of Electronics Engineers of Korea SC
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• v.42 no.5 s.305
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• pp.1-12
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• 2005

A Mobile manipulator - a serial connection of a mobile robot and a task robot - is a very useful system to achieve various tasks in dangerous environment. because it has the higher performance than a fixed base manipulator in regard to the size of it's operational workspace. Unfortunately the use of a mobile robot introduces non-holonomic constraints, and the combination of a mobile robot and a manipulator generally introduces kinematic redundancy. In this paper, first a method for estimating the position of object at the cartesian coordinate system acquired by using the geometrical relationship between the image captured by 2-DOF active camera mounted on mobile robot and real object is proposed. Second, we propose a method to determine a optimal path between current the position of mobile manipulator whose mobile robot is non-holonomic and the position of object estimated by image information through the global displacement of the system in a symbolic way, using homogenous matrices. Then, we compute the corresponding joint parameters to make the desired displacement coincide with the computed symbolic displacement and object is captured through the control of a manipulator. The effectiveness of proposed method is demonstrated by the simulation and real experiment using the mobile manipulator.

• Korean Chemical Engineering Research
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• v.48 no.4
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• pp.470-474
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• 2010

In this study, we presents a simple microfluidic approach for generating uniform Poly(ethylene glycol)(PEG) microfiber. Elongated flow pattern of monomer induced by sheath flow of immiscible oil as continuous phase is generated in Y-shape junction and in situ polymerization by UV exposure. For uniform microfiber, we investigate the optimized flow condition and draw phase diagram as function of Ca and Qd. At the region for stable elongated flow pattern, the microfiber generated in microfluidic chip is very uniform and highly reproducible. Importantly, the thickness of microfibers can be easily controlled by flow rate of continuous and disperse phase. We also demonstrate the feasibility for biological application as encapsulating FITC-BSA in PEG microfiber.

• Journal of the Korean Institute of Telematics and Electronics
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• v.26 no.6
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• pp.7-14
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• 1989

A trajectory control method being capable of singularity avoidance is proposed for a robot and positoner (R-P) system. In the proposed method, the damping factor of the Damped Least Square (DLS) method is adjusted by gradients of trajectory following errors so that the singularity avoidance can be achieved while mimimizing the errors. Two numerical examples are given by employing a Rhino robot with five degrees-of-freedom (d.o.f.) and two d.o.f's, where the method of maximizing the manipulagility the DLS method with a fixd damping factor and the proposed method are compared in terms of trajectory following errors, manipulabilities and joint velocities.

• Journal of Digital Contents Society
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• v.16 no.6
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• pp.917-925
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• 2015

WebRTC is one of the most recent technologies that supports browser-to-browser for voice calling, video chat, and P2P file sharing without the need of either internal or external plugins. However, there has some limitation which lets our development deal with many problems. This research will focus just on a small field of that problem which is bandwidth. While the bandwidth for downloading and uploading is fixed by service providers, but the number of users in a certain area is increasing largely by the time. In this paper, we propose a model to overcome the limitation of the bandwidth based on fuzzy control to adjust utilized bandwidth by changing frame rate and resolution of streaming video in the client itself.