• Publications of The Korean Astronomical Society
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• v.32 no.1
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• pp.359-361
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• 2017

We report our research on aluminum mirror optics for future infrared astronomical satellites. For space infrared missions, cooling the whole instrument is crucial to suppress the infrared background and detector noise. In this aspect, aluminum is appropriate for cryogenic optics, because the same material can be used for the whole structure of the instrument including optical components thanks to its excellent machinability, which helps to mitigate optical misalignment at low temperatures. We have fabricated aluminum mirrors with ultra-precision machining and measured the wave front errors (WFEs) of the mirrors with a Fizeau interferometer. Based on the power spectral densities of the WFEs, we confirmed that the surface accuracy of all the mirrors satisfied the requirements for the SPICA Coronagraph Instrument. We then integrated the mirrors into an optical system, and examined the image quality of the system with an optical laser. As a result, the total WFE is estimated to be 33 nm (rms) from the Strehl ratio. This is consistent with the WFEs estimated from the measurement of the individual mirrors.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.24 no.8
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• pp.798-804
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• 2013

In this paper, conducted emission from the LDC(Low-Side DC/DC Converter) of a HEV/EV was analyzed using high-frequency circuit modeling in system-level approach. The conducted emission by PWM process(100 kHz; Switching Frequency) can cause RFI(Radio-Frequency Interference) problems in the AM/FM frequency range. In order to mitigate this conducted emission, a high-frequency equivalent circuit model is proposed by analyzing the fundamental circuits, parasitic components in their parts and connections and non-linear characteristics of MOSFETs, high-power capacitors, inverters, motors, high-power cables, and bus bars which are composed of the LDC. Using these circuit models, results of both simulation and measurement were compared and similarities between them were verified. We are looking forward that this approach can be effectively used in the EMC design of HEV/EV.

• Journal of Environmental Health Sciences
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• v.42 no.6
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• pp.375-384
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• 2016

Objectives: This paper analyzes the intersection of tort law and environmental health in a recent court decision. Methods: This paper analyzes Supreme Court Decision 2011Da7437, Decided on September 4, 2014 and related lower court decisions. Results: The plaintiffs sought financial compensation from the defendants, arguing that air pollutants in gases emitted by vehicles produced by the defendants had caused them to acquire respiratory diseases. The district court highlighted the need to mitigate the burden of proof for the plaintiffs, but proceeded to review whether the plaintiffs proved the actual toxicity levels of the air pollutants, whether the defendant's vehicles were the main source of the emissions, the plaintiff's level of exposure to the pollutants, and causation between the emissions and the injury. By doing so, the district court required the plaintiffs to prove both indirect and direct facts of causation, increasing burden of proof for plaintiffs. The appellate court upheld the district court's decision, adding that the defendant's conduct did not constitute an illegal act because it did not violate the emissions standards set by environmental law. The Supreme Court upheld the appellate court's decision, reasoning that the epidemiological evidence cannot establish a direct causation for diseases that lack specificity. Conclusion: This case demonstrates that discussions in environmental health have significance in tort lawsuits. For each fact that the plaintiffs and defendants attempted to prove, environmental health research studies were offered as evidence. In addition, the courts decided the legality of the defendant's conduct based on emission standards set by environmental law.

• Asian-Australasian Journal of Animal Sciences
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• v.26 no.1
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• pp.90-96
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• 2013

Effects of dietary Scutellaria baicalensis extract (SBE) on growth, feed utilization and challenge test of olive flounder (Paralichthys olivaceus) were determined. Six hundred thirty fish averaging 5.0 g were distributed into 18, 180-L tanks. Six experimental diets were prepared in triplicate: SBE-0, SBE-0.5, SBE-1, SBE-2, SBE-3 and SBE-5 diets containing SBE at the concentrations of 0, 0.5, 1, 2, 3 and 5%, respectively. Fish were hand-fed to apparent satiation twice a day for 8 wks. At the end of 8-wk feeding trial, ten fish from each tank were infected by Edwardsiella tarda for challenge test. Survival and weight gain of fish were not affected by dietary concentrations of SBE. However, specific growth rate of fish fed the SBE-2 diet was higher than that of fish fed the SBE-0, SBE-1, SBE-3 and SBE-5 diets. Neither feed efficiency nor serum chemical composition of fish was affected by dietary concentrations of SBE. The cumulative mortality of fish fed the SBE-0 diet was 100% at 96 h after E. tarda infection, but 77 to 87% for fish fed the other diets. Dietary inclusion of 2% SBE appears to be recommendable to improve specific growth rate of fish and SBE had the potential to mitigate mortality of fish at E. tarda infection.

• ETRI Journal
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• v.36 no.3
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• pp.352-360
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• 2014

This paper presents a 900 MHz zero-IF RF transceiver for IEEE 802.15.4g Smart Utility Networks OFDM systems. The proposed RF transceiver comprises an RF front end, a Tx baseband analog circuit, an Rx baseband analog circuit, and a ${\Delta}{\Sigma}$ fractional-N frequency synthesizer. In the RF front end, re-use of a matching network reduces the chip size of the RF transceiver. Since a T/Rx switch is implemented only at the input of the low noise amplifier, the driver amplifier can deliver its output power to an antenna without any signal loss; thus, leading to a low dc power consumption. The proposed current-driven passive mixer in Rx and voltage-mode passive mixer in Tx can mitigate the IQ crosstalk problem, while maintaining 50% duty-cycle in local oscillator clocks. The overall Rx-baseband circuits can provide a voltage gain of 70 dB with a 1 dB gain control step. The proposed RF transceiver is implemented in a $0.18{\mu}$ CMOS technology and consumes 37 mA in Tx mode and 38 mA in Rx mode from a 1.8 V supply voltage. The fabricated chip shows a Tx average power of -2 dBm, a sensitivity level of -103 dBm at 100 Kbps with PER < 1%, an Rx input $P_{1dB}$ of -11 dBm, and an Rx input IP3 of -2.3 dBm.

• Journal of the Institute of Electronics and Information Engineers
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• v.50 no.6
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• pp.3-8
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• 2013

Bit patterned media (BPM) storage is one of the promising technologies to overcome the limitations of the conventional magnetic recording. However, there are some problems in a high areal density BPM storage, inter-track interference, inter-symbol interference and noise which are severely degrading performance of the system with reducing the bit error rate. In this paper, we present a simple iterative two-dimensional equalizer based on the contraction mapping theorem to mitigate these adverse effects. Furthermore, we examine that the channel characteristics of the proposed two-dimensional equalizer satisfies the convergence conditions. In the simulation we demonstrate the bit separation characteristics of the one-dimensional equalizer and the two-dimensional equalizer and evaluate the BER performance of the proposed equalizer comparing with the conventional equalizers. According to the results of experiments, the proposed equalizer is an promising equalizer with maintaining proper complexity for a high areal density BPM storage.

• Journal of the Institute of Electronics and Information Engineers
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• v.50 no.8
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• pp.121-127
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• 2013

Memory devices including SRAM and DRAM are very susceptible to high energy radiation particles in the space. Abnormal operation of the devices is caused by SEE or TID. This paper presents a method to estimate proton SEU cross section representing the susceptibility of the latch circuit that the unit cell of the SRAM and proposes a new latch circuit to mitigate the SEU. 50b shift register was fabricated by using the conventional latch and the proposed latch in $0.35{\mu}m$ process. Irradiation experiment was conducted at KIRAMS by using 43MeV proton beam. It was found that the proposed latch-shift register is not affected by the radiation environment compared to the conventional latch-shift register.

• Journal of the Korea society of information convergence
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• v.7 no.2
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• pp.41-48
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• 2014

Capitalism of altitude in modern society has brought a brilliant development of human civilization. But there is a side effect of capitalism. It is just such as alienation of labor, polarization. The need to consider the worker's equal rights to share profits of private companies in the first Korean Constitution of 1948 is to mitigate the adverse effects of this capitalism. It is considered that the present government aims at "economic democracy" slogan and also be matched. The worker's equal rights to share profits of private companies means the distribution rights of workers to receive excess profits of the company. The review of these worker's equal rights to share profits of private companies is thought very meaningful.

• Journal of Hydrogen and New Energy
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• v.31 no.4
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• pp.337-344
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• 2020

Worldwide, there is a significant surge in the efforts for addressing the issue of global warming; the use of renewable energy is one of the solutions proposed to mitigate global warming. However, severe volatility is a critical disadvantage, and thus, power-to-gas technology is considered one of best solutions for energy storage. Hydrogen is a popular candidate from the perspective of both environment and economics. Accordingly, a hydrogen production system based on renewable energy sources is developed, and the economics of the system are assessed. The result of the base case shows that the unit cost of hydrogen production would be 6,415 won/kg H₂, with a hydrogen production plant based on a 100 MW akaline electrolyzer and 25% operation rate, considering renewable energy sources with no electricity cost payment. Sensitivity study results show that the range of hydrogen unit cost efficiency can be 2,293 to 6,984 Won/kg H₂, depending on the efficiency and unit cost of the electrolyzer. In case of electrolyzer operation rate and electricity unit cost, sensitivity study results show that hydrogen unit cost is in the range 934-26,180 won/kg H₂.

• Journal of computational fluids engineering
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• v.10 no.3 s.30
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• pp.9-18
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• 2005

During a hypothetical severe accident in a nuclear power plant (NPP), hydrogen is generated by the active reaction of fuel-cladding and steam in the reactor pressure vessel and released with steam into the containment. In order to mitigate hydrogen hazards possibly occurred in the NPP containment, hydrogen mitigation system (HMS) is usually adopted. The design of the next generation NPP (APR1400) designed in Korea specifies 26 passive autocatalytic recombiners and 10 igniters installed in the containment for the hydrogen mitigation. in this study, the analysis of the hydrogen and steam behavior during a total lose of feed water (TLOFW) accident in the APR1400 containment has been conducted by using the CFD code GASFLOW. During the accident, a huge amount of hot water, steam, and hydrogen is released in the in-containment refueling water storage tank (IRWST). The current design of the APR1400 includes flap-type dampers at the IRWST vents which are operated depending on the pressure difference between inside and outside of the IRWST. it was found that the flaps strongly affects the flow structure of the steam and hydrogen in the containment. The possibilities of a flame acceleration and transition from deflagration to detonation (DDT) were evaluated by using Sigma-Lambda criteria. Numerical results indicate the DDT possibility could be heavily reduced in the IRWST compartment when the flaps are installed.