• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.37 no.6
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• pp.644-648
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• 2024

Human-centric lighting (HCL) aims to enhance well-being and performance by tailoring lighting to human needs. However, LED flicker-rapid brightness changes-remains a critical issue, causing discomfort and reduced productivity. This paper addresses flicker problems in living and industrial spaces with LED lighting. We propose solutions to mitigate flicker by examining causes like power supply variations and LED driver design. Techniques such as high-quality LED drivers, advanced dimming methods, and digital control systems are explored. Our findings show these techniques can significantly reduce flicker, achieving less than 1% flicker performance while meeting HCL's diverse requirements. Implementing flicker-free lighting in residential spaces enhances comfort and reduces eye strain, while in industrial settings, it improves productivity and safety. This paper emphasizes the importance of control circuits that maintain sub-1% flicker performance while integrating various HCL solutions, enhancing indoor lighting quality, and promoting better health and performance.

• Journal of Society of Preventive Korean Medicine
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• v.19 no.1
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• pp.109-116
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• 2015

Objective : Solar ultraviolet (UV) light can cause photoaging of human skin. Many researchers have focused on effective prevention to mitigate the aging process. This study was aimed to investigate anti-wrinkle effects of pomegranate concentration solution (PCS) using photoaged hairless mouse model. Method : To clarify the protective effect of PCS against UVB-induced photo-damage, water capacity was measured with transepidermal water loss (TEWL) in SKH-1 hairless mice. In addition, image of skin replicas was analyzed. Results : Our results showed that the PCS treatment protects skin against UVB-induced photoaging, based on the parameters including moisture capacity and TEWL. According to visual assessment of skin replica, application of 1 ml/kg PCS inhibited UV-induced wrinkle formation in mice skin as compared to the vehicle-applied control mice. Conclusion : Taken together, these results indicated that PCS could improve skin wrinkle formation induced by UVB irradiation in SHK-1 hairless mice. PCS could be applied as an anti-wrinkle agent.

• Journal of Korean Society of Forest Science
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• v.98 no.4
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• pp.458-463
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• 2009

The purpose of this study was to evaluate the changes of surface runoff by comparisons between burned and unburned area after forest fire. The amount of surface runoff in burned area was more high 1.72 times in the year of fire, 1.44 times in one year later, 1.38 times in five years later and 1.16 times in ten years later than those of unburned area. Therefore, surface runoff in the burned area almost tended to be stabilized like unburned area ten year later after forest fire. The most affecting factors on the amount of surface runoff in burned and unburned area were number of unit rainfall, number of rainfall accumulated and unit rainfall. But coverage was shown to mitigate the amount of surface runoff in burned and unburned area.

• Corrosion Science and Technology
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• v.8 no.2
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• pp.74-80
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• 2009

The high alkaline property in the concrete pore solution protects the embedded steel in concrete from corrosion due to aggressive ions attack. However, a continuous supply of those ions, in particular, chlorides altogether with a pH fall in electrochemical reaction on the steel surface eventually depassivate the steel to corrode. To mitigate chloride-induced corrosion in concrete structures, finely grained mineral admixtures, for example, pulverized fuel ash (PFA), ground granulated blast furnace slag (GGBS) and silica fume (SF) have been often advised to replace ordinary Portland cement (OPC) partially as binder. A consistent assessment of those partial replacements has been rarely performed with respect to the resistance of each binder to corrosion, although the studies for each binder were extensively looked into in a way of measuring the corrosion rate, influence of microstructure or chemistry of chlorides ions with cement hydrations. The paper studies the behavior of steel corrosion, chloride transport, pore structure and buffering capacity of those cementitious binders. The corrosion rate of steel in mortars of OPC, 30% PFA, 60% GGBS and 10% SF respectively, with chloride in cast ranging from 0.0 to 3.0% by weight of binder was measured at 7, 28 and 150 days to determine the chloride threshold level and the rate of corrosion propagation, using the anodic polarization technique. Mercury intrusion porosimetry was also applied to cement pastes of each binder at 7 and 28 days to ensure the development of pore structure. Finally, the release rate of bound chlorides (i.e. buffering capacity) was measured at 150 days. The chloride threshold level was determined assuming that the corrosion rate is beyond 1-2 mA/$m^3$ at corrosion and the order of the level was OPC > 10% SF > 60% GGBS > 30% PFA. Mercury intrusion porosimetry showed that 10% SF paste produced the most dense pore structure, followed by 60% GGBS, 30% PFA and OPC pastes, respectively. It was found that OPC itself is beneficial in resisting to corrosion initiation, but use of pozzolanic materials as binders shows more resistance to chloride transport into concrete, thus delay the onset of corrosion.

• The Journal of the Acoustical Society of Korea
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• v.23 no.4
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• pp.288-295
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• 2004

Detection and localization of a slow and quiet target in shallow water environments is a challenging problem for which it is well known that snapshot is deficient because of a fast and strong interferer. This paper presents waveguide interference filtering technique that mitigate strong interferer problems in adaptive matched field processing. MCM (multiple constraint method) based on NDC (null direction constraint) has been proposed for new spatial interferer filter. MCM-NDC using replica force a interferer component to be filtered through CSDM (cross-spectral density matrix). This filtering have an effect on sidelobe reduction and restoring of signal gain of a quiet target. This technique was applied to a simulation on Pekeris waveguide and vertical array data from MAPLE03 (matched acoustic properties and localization experiment) in the East Sea and was shown to improve SBNR (signal-to-background-and-noise ratio) over the standard MVDR (minimum-variance distortionless response) and NSP (null space projection) technique.

• Journal of Arbitration Studies
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• v.15 no.2
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• pp.93-123
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• 2005

As the international commercial transaction has drastically grown up with the mainland China, commercial disputes that are required to settle through ADR have tremendously increased during the last decade. Since China has not been fully exposed to the Free World for a long period of time, there would have been a great amount of misunderstanding about their competency and integrity to deal with internationally oriented commercial transactions with a view to internationally acceptable manner. This arbitration case was related to the contract in dispute of C&A Inc. as the importer v. China XX Importation Co. as the exporter for the sale of Silicon Metal. But after the contract were formed, exporter(respondent) declined to deliver the goods under the contracts because the market price of Silicon Metal increased according to the argument of the importer(claimant). Importer had to purchase alternative goods from other companies to substitute for the goods subject to the contracts in dispute. Importer purchased silicon metal of the same quality as under the contracts from two other Chinese companies as the necessary measure to mitigate the loss, paying prices higher than the contract price. Since exporter had breached the contracts, importer's loss should be compensated by the exporter as the Arbitration Tribunal decided for supporting importer's claim of loss for the substitute goods. This study is aiming at analyzing the rationale of the arbitral awards made by the Shanghai Commission in terms of (l)Place of Arbitration, (2)Applicable Law, (3)Validity of the Contracts, (4)Doctrine of Frustration, (5)Responsibility for the Mitigation of Damage by the Importer.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.29 no.8A
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• pp.859-867
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• 2004

To provide high-quality media streaming service over the best-effort Internet, a streaming methodology is required to response to the dynamic fluctuation of underlying networks. In this paper, we implement the MPEG-4 streaming system with adaptive transport based on priorities of media packets. The implemented system is composed of the common MPEG-4 streaming components such as elementary stream provider, sync and DMIF layer, and adaptive transport module including data prioritization and FEC control. More specifically, the prioritized sync layer packets (based on object level) are delivered to the transport module and then are encoded by an adaptive FEC encoder to help reliable transport. The FEC combination is dynamically adjusted by the feedback information from the receiver. In addition, low priority packets are selectively dropped to meet the limitation of available bandwidth. The experimental results over the emulation-based testbed show that the Proposed system can mitigate the impact of network fluctuation and thus improve the quality of streaming.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.30 no.5A
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• pp.382-388
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• 2005

An OFDM system may be a good candidate for a next-generation wireless communication system which requires high-speed and high-rate data transmission. In OFDM systems, guard intervals are inserted to mitigate the effects of ISI (Inter-Symbol Interference). But guard interval insertion degrades the system performance from the standpoint of data rate and bandwidth efficiency. In this paper, a new method to improve the performance of an OFDM system without guard interval. First, PIC (Parallel Interference Cancellation) scheme which can reduce ISI by subtracting the estimated multi-path components from the received signal will be considered. And the proposed system with Pseudo-Decorrelator estimates transmitted signals by using the inverse matrix of cross-correlation matrix relating to interference components. The performance of the proposed system is evaluated through computer simulations and compared with that of the PIC system and an OFDM system without guard interval.

• Journal of Energy Engineering
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• v.17 no.3
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• pp.145-152
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• 2008

Approaching to the era of high energy price and energy sources scarcity, the demand for governmental intervention to mitigate the short-term shocks is highly increasing. When any energy policy is implemented, double-side effects would be derived. To begin with positive aspect, by decreasing energy import, unnecessary currency outflow can be prevented and the resultant saved money will be appropriately allocated. Furthermore, industrial competitiveness will be assured by reducing use of expensive energy. On the contrary, inappropriate energy saving policy may lead to unexpected negative effects that would hinder improvement in productivity due to indiscreet replacing energy by equipments. In order to enhance effectiveness of energy policy, efforts should be made in advance to understand the energy use pattern of each industry sector which composes the economy. Therefore, in this study, an energy input-output method, one of the macroscopic approaches, is applied to analyze energy use patterns of each industry sector in Korea. Using this method, a quantitative assessment is performed to obtain the energy use intensity and the amount of energy uses with respect to energy types.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.34 no.5
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• pp.605-609
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• 2010

In modern surveillance equipment, infrared (IR) sensors are essential for detection and observation. The IR sensor is connected to a miniature cryogenic cooler to maintain the temperature at very low levels, i.e., temperatures as low as 77 K. However, the quality of the image captured by the sensor is degraded by the transmission of vibration disturbances from the cooler. Therefore, to maintain high image quality, the compressor vibration and the force transmitted to the sensor have to be mitigated. For the compressor vibration isolating system, a tuned dynamic vibration absorber, combined with a passive isolator, is proposed. A cryogenic compressor bracket and springs are designed to allow the absorber mass to mitigate the vibration jitter in the axial direction. The system design is analyzed and evaluated in terms of the dynamic suppression of the harmonic force at the operating frequency of the cooler.