• The Transactions of the Korean Institute of Electrical Engineers D
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• v.53 no.4
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• pp.235-245
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• 2004

In this paper, fault tolerant mechanisms are presented for a servo manipulator system designed to operate in a hot cell. A hot cell is a sealed and shielded room to handle radioactive materials, and it is dangerous for people to work in the hot cell. So, remote operations are necessary to handle the radioactive materials in the hot cell. KAERI has developed a servo manipulator system to perform such remote operations. However, since electric components such as servo motors may fail by radiation, fault tolerant mechanisms have to be considered. For fault tolerance of the servo manipulator system, duplication mechanism increasing the reliability of the transport's driving motors and reconfiguration algorithm accommodating the slave's motor failure have been presented. The reconfiguration algorithm recovering the end effector's motion in spite of one motor's failure is based on control allocation redistributing redundant axes. The constrained optimization method and pseudo inverse method have been adopted for control allocation. Simulation examples and real test results have been presented to verify the Proposed methods.

• Nuclear Engineering and Technology
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• v.40 no.4
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• pp.319-326
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• 2008

To transport process wastes efficiently from the Advanced Spent Fuel Conditioning Pyro-process Facility (ACPF) at the Korea Atomic Energy Research Institute (KAERI), a new hot cell cask has been designed based on an existing hot cell padirac transport cask, with not only a neutron absorber for improved shielding capability, but also a docking facility for an easy docking system. In the new hot cell cask, two kinds of materials have been considered as shielding materials, polyethylene and resin. To verify the transport compatibility of the waste and spent fuel for the ACPF, neutron and photon shielding calculations were performed using the MCNPX code. The source term was evaluated by the ORIGEN-ARP code system based on spent PWR fuel. From the calculation, it was found that the maximum surface dose rates of the hot cell cask with the two candidates were estimated within the limit (2 mSv/hr).

• Journal of the Korea Academia-Industrial cooperation Society
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• v.15 no.7
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• pp.4065-4071
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• 2014

The analysis results of the temperature distribution and deformation at the PV cell with a thickness of $200{\mu}m$ according to hot-air temperature at the soldering process of a PV cell and ribbon tend to agree somewhat with the experimental measured values. The best result of the electrical efficiency appears in the module soldered at a hot-air temperature of $390^{\circ}C$. An analysis of the soldering PV cell with a thickness of $150{\mu}m$ at a hot-air temperature of $350^{\circ}C$ confirmed that the maximum deformation was approximately 5.9mm. As the temperature of hot air is set to decrease, the deformation is reduced and it is predicted that the electrical efficiency can be improved.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1995.10a
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• pp.1182-1185
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• 1995

This paper presents a novel technology for unattented continuous monitoring of radioactive material in hot cell environments. In this monitoring system, the surveillance camera data and NDA data are time synchronized and integrated into the same dimension through data processing. The integrated information is then fed into a neural network to generate diagnostics through data processing. the integrated information of the concept is tested for a spent nuclear fuel transprotation in an operational hot cell at KAERI. The presented integral part of the multi-sensory system and the analytical paradigm may provide an effective technologyical alternative for safeguarding new conceptual hot cell facilities, namely the Dupic facility.

• ETRI Journal
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• v.28 no.3
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• pp.282-290
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• 2006

In vertically overlaid cellular systems, a temporary traffic concentration can occur in a hot-spot area, and this adversely affects overall system capacity. In this paper, we develop an adaptive hot-spot operating scheme (AHOS) to mitigate the negative effects from the nonuniform distribution of user location and the variation in the mixture of QoS requirements in orthogonal frequency division multiple access downlink systems. Here, the base station in a macrocell can control the operation of picocells within the cell, and turns them on or off according to the system overload estimation function. In order to determine whether the set of picocells is turned on or off, we define an AHOS gain index that describes the number of subcarriers saved to the macrocell by turning a specific picocell on. For initiating the picocell OFF procedure, we utilize the changes in traffic concentration and co-channel interference to the neighboring cells. According to computer simulation, the AHOS has been proved to have maximize system throughput while maintaining a very low QoS outage probability under various system scenarios in both a single-cell and multi-cell environments.

• Proceedings of the Korean Vacuum Society Conference
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• 2013.08a
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• pp.310.1-310.1
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• 2013

We show the novel hot electron based-solar energy conversion using tandem structured Schottky diode with double Schottky barriers. In this report, we show the effect of the double Schottky barriers on solar cell performance by enhancing both of internal photoemission and band-to-band excitation. The tandem structured Au/Si diode capped with TiO2 layer as second semiconductor exhibited improved ability for light harvesting. The proposed mechanisms consist of multiple reflections of hot electrons and additional pathway of solar energy conversion due to presence of multiple interfaces between thin gold film and semiconductors. Short-circuit photocurrent measured on the tandem structured Au/Si diodes under illumination of AM1.5 increased by approximately 70% from 3.1% to 5.3% and overall incident photon to electron conversion efficiency (IPCE) was enhanced in visible light, revealing that the concept of the double Schottky barriers have significant potential as novel strategy for light harvesting.

• Journal of Oriental Neuropsychiatry
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• v.19 no.3
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• pp.55-68
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• 2008

Background: Microglia produces a barrage of factors (IL-l, TNF-$\alpha$, NO, superoxide) that are toxic to neurons and playa major role in the cellular immune response associated with the pathology of Alzheimer's disease(AD). OJaJiHwangEumJa(OJJHEJ) has been usually used for the treatment of senile disorders. For enhancing efficacy and convenience, the change of the drug delivery device of oriental herbal medicine is required. Objective: This experiment was designed to investigate the effect of the OJJHEJ hot water extract & ultra-fine powder on proinflammatory cytokine of microglia and memory deficit model. Method: The effects of the OJJHEJ hot water extract on production of IL-1$\beta$, IL-6, TNF-$\alpha$, in BV2 microglial cell line treated by lipopolysacchaide(LPS) were investigated. The effects of the OJJHEJ hot water extract & ultra-fine powder on the behavior of the memory deficit mice induced by scopolamine and AChE in serum of the memory deficit mice induced by scopolamine were investigated. Results: 1. The OJJHEJ hot water extract suppressed the production of IL-1$\beta$, IL-6, TNF-$\alpha$ in BV2 microglial cell line and the production of IL-6 was suppressed significantly. 2. The OJJHEJ hot water extract & ultra-fine powder decreased AChE significantly in the serum of the memory deficit mice induced by scopolamine. 3. The OJJHEJ hot water extract & ultra-fine powder groups showed significantly inhibitory effect on the scopolamine-induced impairment of memory in the experiment of Morris water maze. Conclusions: This experiment shows that the OJJHEJ hot water extract & ultra-fine powder might be effective for the prevention and treatment of memory impairment diseases. Investigation into the clinical use of the OJJHEJ hot water extract & ultra-fine powder for Alzheimer's disease is suggested for future research.

• Proceedings of the Korean Radioactive Waste Society Conference
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• 2005.06a
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• pp.74-75
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• 2005

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.21 no.1
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• pp.12-17
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• 2008

In this paper, an I-V characteristics of bypass diode has been studied by counting the shading effect in photovoltaic module. The shadow induces hot spot phenomenon in PV module due to the increase of resistance in the current path. Two different types of PV module with and without bypass diode were fabricated to expect maximum output power with an increasing shading rate of 5 % on the solar cell. Temperature distribution is also detected by shading the whole solar cell for the outdoor test. From the result, the bypass diode works properly over 60 % of shading per cell with constant output power. Maximum power generation in case of solar cell being totally shaded with bypass diode decreases 41.3 % compared with the one under STC(Standard Test Condition). On the other hand, the maximum output power of the module without bypass diode gradually decreases by showing hot spot phenomenon with the increase of shading ratio on the cell and finally indicates 95.5 % of power loss compared with the output under STC. Finally the module temperature measured increases around $10^{\circ}C$ higher than that under STC due to hot-spots which come from the condition without bypass diode. It has been therefore one of the main reasons for degrading the PV module and shortening the durability of the PV system.

• Journal of KIISE:Information Networking
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• v.32 no.3
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• pp.404-414
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• 2005

In the packet data network systems beyond 3G, the service quality of current users is affected by traffic load due to the packet burstiness. There also exists a hot cell problem, a well-known problem of cellular systems, caused by traffic centraliBation. Hot cell problem is one of the major reasons of degrading system performance because hot cell increases the call drop rate without fully utilization of system resource. Therefore, it is very important to distribute the traffic on the several neighboring cells so that system uses its resource effectively and maintains the quality of service. In this paper, we propose the adaptive handoff algorithms for distributing traffic in the packet data network systems. In addition, we propose a new load estimation method with MAC state diagram suitable for packet data network systems. Through the simulation results, we could find that proposed algorithm is able to improve efficiency of system resource and to assure the service quality of users through traffic distribution.