• Proceedings of the Korean Geotechical Society Conference
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• 2004.03b
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• pp.475-482
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• 2004

The purpose of this paper is to study on the investigation of abandoned waste landfill for rehabilitation. The geotechnical and environmental field and laboratory tests for wastes dumped at municipal site were carried out. Testing wastes were sampled at the illegal landfill site The various samples such as waste. soil, groundwater, gas, leachate were taken in the landfill site. As a result of this study, the engineering properties and concentration of samples were investigated The result of this study was used for introduction the rehabilitation method and treatment of unregulated closed landfill.

• Journal of Power Electronics
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• v.11 no.4
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• pp.551-560
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• 2011

This paper proposes a grid-tied power conditioning system for the fuel cell power generation, which consists of a 2-stage DC-DC converter and a 3-phase PWM inverter. The 2-stage DC-DC converter boosts the fuel cell stack voltage of 26-48V up to 400V, using a hard-switching boost converter and a high-frequency unregulated LLC resonant converter. The operation of the proposed power conditioning system was verified through simulations with PSCAD/EMTDC software. Based on the simulation results, a laboratory experimental set-up was built with a 1.2kW PEM fuel-cell stack to verify the feasibility of hardware implementation. The developed power conditioning system shows a high efficiency of 91%, which is a very positive result for the commercialization.

• Proceedings of the IEEK Conference
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• 2006.06a
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• pp.897-898
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• 2006

This paper proposes a new power-stage circuit that can be available for modularization of the power regulator which is used at the software-controlled unregulated bus system. And we analyze the proposed power-stage operation according to its operating modes and verify it by performing software simulation and hardware experiment using prototype. By constructing a parallel-module converter which is composed of proposed power-stages, we verify the operations and usefulness of the proposed power-stage.

• Journal of Power Electronics
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• v.11 no.6
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• pp.811-818
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• 2011

Modulation strategies for multilevel inverters have typically focused on synthesizing a desired set of sinusoidal voltage waveforms using a fixed number of dc voltage sources. This makes the average power drawn from different dc voltage sources unequal and time varying. Therefore, the dc voltage sources are unregulated and require that corrective control action be incorporated. In this paper, first two new selections are proposed for determining the dc voltage sources values for asymmetric cascaded multilevel inverters. Then two modulation strategies are proposed for the dc power balancing of these types of multilevel inverters. Using the charge balance control methods, the power drawn from all of the dc sources are balanced except for the dc source used in the first H-bridge. The proposed control methods are validated by simulation and experimental results on a single-phase 21-level inverter.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 1999.11a
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• pp.110-115
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• 1999

The emergence of portable information terminals in work and living environments is accelerating introduction of wireless digital links and local-area networks(LANs). Transmission using infrared radiation recently become a viable option. As a transmission medium, infrared offers several advantage over radio. The infrared spectral region offers a virtually unlimited bandwidth that is unregulated worldwide. In this paper we examine the performance of several modulation schemes on the wireless infraredcommunication system. We compare the power and bandwidth efficiency of several schemes.

• KIEE International Transaction on Electrical Machinery and Energy Conversion Systems
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• v.3B no.3
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• pp.139-146
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• 2003

In this paper, the steady-state operating performance analysis for the three-phase squirrel cage rotor self-excited induction generator (SEIG) driven by a variable-speed prime mover (VSPM) in addition to a constant-speed prime mover (CSPM) is presented on the basis of an effective algorithm based on its frequency-domain equivalent circuit. The operating characteristics of the three-phase SEIG coupled by a VSPM and/or a CSPM are evaluated on line processing under the condition of the electrical passive load parameters variations with simple and efficient computation processing procedure in unregulated voltage control loop scheme. A three-phase SEIG prototype setup with a VSPM as well as a CSPM is implemented for the small-scale clean renewable and alternative energy utilizations. The experimental operating characteristic results are illustrated and give good agreements with the simulation ones.

• Transactions of the Korean Society of Automotive Engineers
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• v.6 no.6
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• pp.218-225
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• 1998

FTIR spectroscopy, useful technology for simultaneous and continuous measurement of the various components of the automotive exhaust gas, is utilized to investigate catalytic reaction charactristics of methane and a few unregulated exhaust emissions of NGV. Major findings are (1) catalytic reaction characteristics of methane measured in unsteady states of varying temperature are similar to those measured in steady states, (2) about 24 % of NO was oxidized to $NO_2$ as soon as they encounter catalysts, (3) study of formaldehyde suffers from difficulties in measurement due to the proximity in wavenumber of formaldehyde and methane, and requires an analyzer of higher resolution and accuracy than used in this study.

• Proceedings of the KIEE Conference
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• 2005.07b
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• pp.1438-1440
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• 2005

A power control and distribution unit(PCDU) plays roles of protection of battery against overcharge by active control of solar array generated power, distribution of unregulated electrical power via controlled outlets to bus and instrument units, distribution of regulated electrical power to selected bus and instrument units, and provision of status monitoring and telecommand interface allowing the system and ground operate the power system, evaluate its performance and initiate appropriate countermeasures in case of abnormal conditions. In this work, we perform the preliminary design of a PCDU scheme for the small LEO Satellite applications. The main constitutes of the PCDU are the battery interface module, the auxiliary supply modules, solar array regulators with maximum power point tracking(MPPT) technology, heater power distribution modules, internal converter modules for regulated bus voltage generation. and instrument power distribution modules.

• International Journal of Computer Science & Network Security
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• v.22 no.2
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• pp.185-192
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• 2022

Forecasting and time series modelling plays a vital role in the data analysis process. Time Series is widely used in analytics & data science. Forecasting stock prices is a popular and important topic in financial and academic studies. A stock market is an unregulated place for forecasting due to the absence of essential rules for estimating or predicting a stock price in the stock market. Therefore, predicting stock prices is a time-series problem and challenging. Machine learning has many methods and applications instrumental in implementing stock price forecasting, such as technical analysis, fundamental analysis, time series analysis, statistical analysis. This paper will discuss implementing the stock price, forecasting, and research using prophet and LSTM models. This process and task are very complex and involve uncertainty. Although the stock price never is predicted due to its ambiguous field, this paper aims to apply the concept of forecasting and data analysis to predict stocks.

• Journal of the Korean Applied Science and Technology
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• v.34 no.1
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• pp.12-24
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• 2017

The main purpose of this research is for the investigation on the impact of engine oil aging on PM and DPF. It is widely known that lubricant specifications and consumption from an ICE have significantly influenced on the regulated and unregulated harmful emissions as the engine operating conditions. Considering DPF clogging phenomena with lubricant-derived soot/ash components, simulated aging mode for the DPF was newly designed for engine dynamometer testing. PM/ash accumulation cycle were developed in reflecting real-world engine operating conditions for the increment of engine oil consumption and natural DPF regeneration for the ash accumulation. The test duration for DPF aging reached around 100hrs with high- and low-SAPS engine oils, respectively. Using high SAPs engine oil made more PM/ash accumulation compared with low SAPs engine oils and it could accelerate fouling of EGR in engine. Fouling of EGR made effects on more harmful exhaust gases emissions. The test results on engine lubricant under engines operating conditions will deliver for the establishment of regulated and unregulated toxic emissions policy, lubricant quality standard.