• Proceedings of the KIEE Conference
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• 2003.07e
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• pp.166-170
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• 2003

This paper deals with the power loss analysis of voltage source type space voltage vector modulated soft switching inverter, and proposed the new voltage vector correction principle during one sampling period on realize high quality cutput voltage waveforms for two soft-swiching approches. The operating pinciple of a single active auxiliary resonant DC link snubber circuit is described. Moreover, the effectiveness of soft switching inverter operating under the corrected voltage pattern is proved on the basis of simulation and experimental results.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.20 no.2
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• pp.191-198
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• 2010

The noise by the construction activities is one of the main issues in Korea. To prevent the noise from construction site, construction company installs temporary noise barriers along the construction site boundary. Normally sound insulation performance ($R_w$) of the temporary noise barriers made by metal or plastic is between 18 and 31 dB and metallic noise barriers are around 5 dB higher than plastic noise barriers. Sound absorption performance (NRC) of the temporary noise barriers are between 0.20 and 0.59 so it's difficult to characterize their acoustic performance. In this study, it has founded that sound insulation performance of the temporary noise barrier has been improved about 3dB by stick the high density acoustic sheet and insertion loss of noise barrier is getting increased as the source and receiver approached the temporary noise barriers.

• Proceedings of the KIEE Conference
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• 1996.07a
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• pp.501-503
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• 1996

In this paper, a novel control strategy for PWM current source converter and inverter is proposed, applying a multivariable state feedback control. The PWM converter controls line current to be sinusoidal and make input power factor unity. In addition, the modulation index control of dc link current is carried out, which produces lower loss of switching devices. Since the voltage control of inverter output filter capacitor is performed a decoupling of the d-q current of the induction motor is well retained. With the proposed algorithm, both high dynamic responses and satisfactory static performance can obtained.

• Journal of the Korean earth science society
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• v.26 no.2
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• pp.114-128
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• 2005

Fuzzy information representation of multi-source spatial data is applied to landslide hazard mapping. Information representation based on frequency ratio and non-parametric density estimation is used to construct fuzzy membership functions. Of particular interest is the representation of continuous data for preventing loss of information. The non-parametric density estimation method applied here is a Parzen window estimation that can directly use continuous data without any categorization procedure. The effect of the new continuous data representation method on the final integrated result is evaluated by a validation procedure. To illustrate the proposed scheme, a case study from Jangheung, Korea for landslide hazard mapping is presented. Analysis of the results indicates that the proposed methodology considerably improves prediction capabilities, as compared with the case in traditional continuous data representation.

• Journal of Power Electronics
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• v.18 no.5
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• pp.1325-1335
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• 2018

This paper presents a discontinuous pulse width modulation (DPWM) method to reduce switching losses in an indirect matrix converter (IMC) drive. The IMC has a number of power semiconductor switches. In other words, it consists of a rectifier stage and an inverter stage for AC/AC power conversion, which are composed of 12 and 6 switching devices, respectively. Therefore, the switching devices of the IMC suffer from high switching losses in the IMC drives. Various topologies to reduce switching losses have been studied by eliminating a number of switches from the rectifier stage. In this study, in contrast to prior research, a DPWM method is presented to reduce the switching losses of the inverter stage. The effectiveness of the proposed method to reduce switching losses in IMC drives is verified by simulations and experimental results.

• Journal of Power Electronics
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• v.10 no.1
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• pp.43-50
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• 2010

This paper proposes a new harmonic elimination PWM (HEPWM) scheme for voltage source inverters (VSI) based on the curve fittings of certain polynomials functions. The resulting equations to calculate the switching angle of the HEPWM require only the addition and multiplication processes; therefore any number of harmonics to be eliminated and the fundamental amplitude of the pole switching waveform (NP1) can be controlled on-line. An extensive angle error analysis is carried out to determine the accuracy of the algorithm in comparison to the exact solution. To verify the workability of the technique, an experimental single phase VSI is constructed. The algorithm is implemented on a VSI using a 16-bit microprocessor. The results obtained from the test rig are compared to the theoretical prediction and the results of the MATLAB simulations.

• Journal of Electrochemical Science and Technology
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• v.7 no.2
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• pp.139-145
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• 2016

The electrochemical performance of carbon-coated LiMn₂O₄ nanoparticles was reported. The polydopamine layer was introduced as a new organic carbon source. The carbon layer was homogeneously coated onto the surface of the LiMn₂O₄ nanoparticles because the polymerization process from the dopamine solution (in a buffer solution, pH 8.5) easily and uniformly formed a polydopamine layer. The phase integrity of LiMn₂O₄ deteriorated during the carbon-coating process due to oxygen loss, although the main structure was maintained. The carbon-coated sample led to improved rate capability because of the effect of the conductive carbon layer. Moreover, the carbon coating also enhanced the cyclic performance. This indicates that the carbon layer may suppress unwanted side reactions with the electrolytes and compensate for the low electronic conductivity of the pristine LiMn₂O₄.

• Proceedings of the KIPE Conference
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• 1998.10a
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• pp.341-345
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• 1998

This paper presents performance and loss analysis of Auxiliary Resonant Commutation Snubber-linked (ARCS) three phase voltage source soft switching inverter which is operated under a condition of Zero Voltage Switching (ZVS). The system performances of this ARCS soft switching inverter which is controlled on optimal type I digital servo scheme are illustrated and evaluated on the basis of experimental results.

• Proceedings of the IEEK Conference
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• summer
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• pp.57-60
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• 2004

Next generation wireless network is evolving toward IP-based network that can various provide multimedia services. A challenge in wireless mobile Internet is support of quality of service over wireless access networks. DiffServ architecture is proposed for evolving wireless mobile Internet. In this paper we propose an algorithm for optimal buffer partitioning which requires the minimal channel capacity to satisfy the QoS requirements of input traffic. We used a partitioned buffer with size B to serve a layered traffic at each DiffServ router. We consider a traffic model with a single source generates traffic having J $(J\geq2)$ quality of service (QoS) classes. QoS in this case is described by loss probability $\varepsilon_j$. for QoS class j. Traffic is admitted or rejected based on the buffer occupancy and its service class. Traffic is generated by heterogeneous Markov-modulated fluid source (MMFS).

• KIEAE Journal
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• v.13 no.2
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• pp.61-66
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• 2013

This study is to eliminate the need for conventional high density plant factory's artificial light source such as LED to reduce the initial investment of the light source installation as well as the operation cost. Use of solar light could enhance the quality of the vegetables similar to those grown in the natural environment. Provision of solar light into the multilayer vegetable cultivation facilities and collecting maximum and sustainable sunlight without too much loss by tracing solar path and properly distributing it through careful control during daytime are crucial for realizing the investigated rooftop light shelf system for multi-layered vegetable cultivation. In this study, we developed an innovative way of effectively allocating sunlight inside even to otherwise shaded zone of a multi-layer vegetable cultivation facility. To prove the effectiveness of the system's sunlight collection and distribution capability, both simulation and experiment in Daejeon are performed and the outcome is analyzed.