• Korean Journal of Materials Research
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• v.8 no.2
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• pp.126-130
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• 1998

Aluminum sulfate, $AI_{2}(SO_4)_3\cdot18H_2O$ was prepared by adding of kaolin-dissolved sulphuric acid into ethanol and its thermal decomposition behavior was discussed. As-synthesized high purity precipitate particles were platelike shapes of $2\mu\textrm{m}$ size. With increasing drop rate of leach liquor into ethanol, the crystallite sizes of the precipitate decreased. The apparent activation energies for dehydration and sulfate decomposition of the precipitate were $11.9Kcal mol^{-1}$ and $48.2kcal mol^{-1}$ respectively.

• Journal of the Mineralogical Society of Korea
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• v.23 no.3
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• pp.251-265
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• 2010

A column bioleaching experiment at room temperature with no addition of sulfuric acid was effectively carried out to leach the valuable elements from pyrite, which is common mine waste. The Fe concentration of pyrite leachate from bioleaching column was 14 times higher than that of the control leachate, and secondary minerals were not formed. The $SO_4^{2-}$ concentration of the pyrite leachate was 2.99 times higher. The XRD intensity of the (111), (200), (220), (311), (222), (230) and (321) planes of pyrite decreased, whereas the intensity of (210) and (211) increased after column bioleaching.

• Proceedings of the IEEK Conference
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• summer
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• pp.193-198
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• 2004

In variety of environments for applications, wireless sensor networks have received increasing attention in the recent few years. But, sensor nodes have many limitations including battery power and communication range. These networks require robust wireless communicant protocols that are energy efficient and provide low latency. In this paper, we propose new protocol as is defined SCP. The key idea of SCP is that only one node which is defined as a Super-Cluster Header sends the combined data to the BS. We evaluated the effectiveness of SCP through experiments which have several parameter violations. Simulation results shows that performance of SCP is through better than other legacy protocol within the framework of energy cost, life time of the sensor network and fair distribution of the energy consumption.

• Nuclear Engineering and Technology
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• v.25 no.1
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• pp.63-70
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• 1993

A simplified safety assessment is carried out on rock-cavern type disposal of LLW using the analytical repository source term (REPS) model. For reliable prediction of the leach rates for various radionuclides, degradation of concrete structures, corrosion rate of waste container, degree of corrosion on the container surface, and the characteristics of radionuclides are considered in the REPS model. The results of preliminary assessment show that Cs-137, Ni-63, and Sr-90 are dominant. For the parametric uncertainty and sensitivity analysis, Latin hypercube sampling technique and rank correlation technique are applied. The results of the potential public health impacts show that radiological dose to intruder in the worst case scenario will be negligible and that more attention should be given to near-field performance.

• Hwankyungkyoyuk
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• v.23 no.4
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• pp.112-123
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• 2010

The purpose of this study is to investigate the elementary school teachers' perception about the aquatic ecosystem restoration and confirm their ideas about factors for successful restoration and the effective direction of education for the aquatic ecosystem restoration. In order to analyze teachers' thoughts about the aquatic ecosystem restoration, in-depth interview was conducted to three elementary school teachers. Then, answers of them were transcribed and analyzed by similarities and differences among subjects. The results are as follows. Elementary school teachers thought about aquatic ecosystem restoration was divided into rehabilitation and remediation. They recognized that factors for successful restoration are the restoration to natural conditions, providing persistent benefit to local residents, and the participation of local community in the process of restoration. Teachers think that they must have correct knowledge and perception regarding the aquatic ecosystem restoration. They also think that contents about the aquatic ecosystem restoration should be taught in elementary school. They mention that they may leach students about the aquatic ecosystem restoration in discretionary activities class and extracurricular activities class. They also mention that the education for aquatic ecosystem restoration might be handled within diverse subjects.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.33 no.5B
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• pp.253-259
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• 2008

Because a sensor node in wireless sensor networks is battery operated and energy constrained, reducing energy consumption of each node is one of important issues. The clustering technique can make network topology be hierarchical and reduce energy consumption of each sensor node. In this paper, we propose an efficient clustering mechanism considering overlap avoidance in wireless sensor networks. The proposed method consists of three parts. The first is to elect cluster heads considering each node's energy. Then clusters are formed by using signal strength in the second phase. Finally we can reduce the cluster overlap problem derived from two or more clusters. In addition, this paper includes performance evaluation of our algorithm. Simulation results show that network lifetime was extended up to 75 percents than LEACH and overlapped clusters are decreased down to nearly zero percents.

• 연구논문집
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• s.31
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• pp.5-14
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• 2001

These days, interest in the leaching of hazardous heavy metals to consist of incinerator fly ash is increasing, because the heavy metals that leach from the incinerator fly ash pollute the soil and ground water. Therefore this study was undertaken to crystallize the fly ash and prevent the leaching of hazardous heavy metals from fly ash. The concentrations and the leaching concentration of hazardous heavy metals(Cd, Cr, Hg, Pb, Zn) in the law incinerator fly ash have been measured. The fly ash was melted with two kinds of flux($Na_2CO_3, CaCO_3$) and its add quantity(0, 1, 2, 3 wt%). The crystal structure of melting materials was analyzed by SEM(Scaning Electron Microscope) and X-RD(X-Ray Diffractometer). The leaching test of melting materials was undertaken. And the relation between crystallization of melting materials and flux and leaching concentration. These experiments indicate that the concentration and leaching concentration of heavy metals in incinerator fly ash was much higher than the regulatory standard for leachates in Korea and U.S.A and average concentration of heavy metals in soil. And the crystal structure was better.

• Journal of Information Processing Systems
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• v.1 no.1 s.1
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• pp.49-54
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• 2005

With the recent advances in Micro Electro Mechanical System (MEMS) technology, low cost and low power consumption wireless micro sensor nodes have become available. However, energy-efficient routing is one of the most important key technologies in wireless sensor networks as sensor nodes are highly energy-constrained. Therefore, many researchers have proposed routing protocols for sensor networks, especially cluster-based routing protocols, which have many advantages such as reduced control messages, bandwidth re-usability, and improved power control. Some protocols use information on the locations of sensor nodes to construct clusters efficiently. However, it is rare that all sensor nodes know their positions. In this article, we propose another cluster-based routing protocol for sensor networks. This protocol does not use information concerning the locations of sensor nodes, but uses the remaining energy of sensor networks and the desirable number of cluster heads according to the circumstances of the sensor networks. From performance simulation, we found that the proposed protocol shows better performance than the low-energy adaptive clustering hierarchy (LEACH).

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2009.05a
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• pp.306-309
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• 2009

MANET(Mobile Ad-hoc Network)은 기간망에 의존하지 않는 이동 노드들로 구성된 자율망 또는 추론망 토폴로지에 의한 멀티홉 무선 네트워크이다. MANET을 구성하는 각 노드의 이동성, 속도 그리고 에너지와 같은 다양한 속성정보는 망의 특징과 운영을 결정하는 요인이다. 특히 망의 운영상, 전송 대역폭과 에너지 사용에 따른 제약을 가지며 이러한 특징을 고려한 라우팅 프로토콜의 설계 및 하드웨어 개발이 중요하게 요구된다. 본 논문에서는 계층적 클러스터 구조의 MANET 환경에서 노드의 에너지 속성과 네트워크의 트래픽 상태를 고려한 적응적 시간차 노드관리 기법인 ATICC(Adaptive Time Interval Clustering Control)을 제안한다. 제안된 ATICC은 시간차 노드 관리기법인 TICC(Time Interval Clustering Control)[1]에 기반하며 노드에 최적화된 Active/Sleep, Idle Listening 상태를 적응적으로 설정한 후 패킷을 전송함으로서 계층적 클러스터 내의 각 노드의 균형적인 에너지 소모를 이루는 에너지 효율적인 방식이다. 제안한 노드관리 방법은 기존의 LEACH, TICC과 비교 실험하고 그 성능을 검증하였다. 실험 결과, 제안한 노드관리 방법이 노드별 에너지 소모량을 줄였으며 전체 네트워크의 생존시간을 연장함으로서 기존의 방법 보다 우수함을 확인하였다.

• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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• v.19 no.3
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• pp.339-352
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• 2021

Legacy waste from the decommissioned A-1 nuclear power plant in the Slovak Republic is scheduled for immobilisation within a tailored alkali borosilicate glass formulation, as part of ongoing site cleanup. The aqueous durability and characterisation of a simulant glass wasteform for Chrompik III legacy waste, was investigated, including dissolution experiments up to 112 days (90℃, ASTM Type 1 water). The wasteform was an amorphous, light green glassy product, with no observed phase separation or crystalline inclusions. Aqueous leach testing revealed a suitably durable product over the timescale investigated, comparing positively to other simulant nuclear waste glasses and vitreous products tested under similar conditions. Iron and titanium rich precipitates were observed to form at the surface of monolithic samples during leaching, with the formation of an alkali deficient alteration layer behind these at later ages. Overall this glass appears to perform well, and in line with expectations for this chemistry, although longer-term testing would be required to predict overall durability. This work will contribute to developing confidence in the disposability of vitrified Chrompik legacy wastes.