• Proceedings of the Korean Vacuum Society Conference
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• 2014.02a
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• pp.307-307
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• 2014

정보화 시대로 접어들면서 동일한 공간에 더 많은 정보를 저장할 수 있고, 보다 빠른 동작이 가능한 비휘발성 메모리 소자에 대한 요구가 증가하고 있다. 하지만, 최근 비휘발성 메모리 소자 관련 연구보고에 따르면, 메모리 소자의 소형화 및 직접화 측면에서, 전하 저장을 기반으로 하는 기존의 Floating-Gate(FG) Flash 메모리는 20 nm 이하 공정에서 한계가 예측 되고 있다. 따라서, 이러한 FG Flash 메모리의 한계를 해결하기 위해, 기존에 FET 기반의 FG Flash 구조와 같은 3 terminal이 아닌, Diode와 같은 2 terminal로 동작이 가능한 ReRAM, PRAM, STT-MRAM, PoRAM 등 저항변화를 기반으로 하는 다양한 종류의 차세대 메모리 소자가 연구되고 있다. 그 중, 저항 변화 메모리(ReRAM)는 CMOS 공정 호환성, 3D 직접도, 낮은 소비전력과 빠른 동작 속도 등의 우수한 동작 특성을 가져 차세대 비휘발성 메모리로 주목을 받고 있다. 또한, 상하부 전극의 2 terminal 만으로 소자 구동이 가능하기 때문에 Passive Crossbar-Array(CBA)로 적용하여 플래시 메모리를 대체할 수 있는 유력한 차세대 메모리 소자이다. 하지만, 이를 현실화하기 위해서는 Passive CBA 구조에서 발생할 수 있는 Read Disturb 현상, 즉 Word-Line과 Bit-Line을 통해 선택된 소자를 제외하고 주변의 다른 소자를 통해 흐르는 Sneak Leakage Current(SLC)를 차단하여 소자의 메모리 State를 정확히 sensing하기 위한 연구가 선행 되어야 한다. 따라서, 현재 이러한 이슈를 해결하기 위해서, 많은 연구 그룹에서 Diodes, Threshold Switches와 같은 ReRAM에 Selector 소자를 추가하는 방법, 또는 Self-Rectifying 특성 및 CRS 특성을 보이는 ReRAM 구조를 제안 하여 SLC를 차단하고자 하는 연구가 시도 되고 있지만, 아직까지 기초연구 단계로서 아이디어에 대한 가능성 정도만 보고되고 있는 현실 이다. 이에 본 논문은 Passive CBA구조에서 발생하는 SLC를 해결하기 위한 새로운 아이디어로써, 본 연구 그룹에서 선행 연구로 확보된 안정적인 저항변화 물질인 SiN를 정류 특성을 가지는 n-Si/Ti 기반의 Schottky Diode와 결합함으로써 기존의 CBA 메모리의 Read 동작에서 발생하는 SLC를 차단 할 수 있는 1SD-1R 구조의 메모리 구조를 제작 하였으며, 본 연구 결과 기존에 문제가 되었던 SLC를 차단 할 수 있었다.

• Korean Journal of Materials Research
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• v.6 no.4
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• pp.379-387
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• 1996

본 연구에서는 GaAs 소자제작 및 epi-layer 성장 공정에 있어 이용되어지는 HCI, H3PO4, 탈이온수(de-ionized water:DIW)를 통한 습식제정후 공기중 노출에 따른 오염을 최소화하여 표면상태 변화를 진성적(intrinsic)으로 관찰하고자 모든 세정처리를 아르곤 가스(argon gas)로 분위기가 유지되는 glove box에서 수행하였으며, 표면조성 및 결합상태 변화에 대한 관찰은 X-선 광전자 분광기(X-ray photoelectron spectroscopy)를 통해 이루어졌다. 고진공하에서 GaAs를 벽개하여 관찰함으로써 Ga이 대기중 산소이온과 우선적으로 결합함을 알 수 있었고, 이런 GaAs 표면의 반응성에 대한 고찰을 바탕으로 습식세정에 따른 화학반응 기구가 제시 되어졌다. HCI 및 H3PO4/DIW/HCI처리후 CI-이온의 Ga 이온과의 반응에 의한 Ga-CI결합의 형성과 As 산화물의 높은 용해도에 따른 As 산화물의 완전한 제거 및 식각전 초기(bare)GaAsvyaus에 존재하는 원소(elemental)As 상태의 식각후 잔류가 관찰되어졌다. 또 HCI, H3PO4/DIW/HCI 처리하고 DIW로 세척후 표면상태 변화를 관찰한 결과, DIW처리에 의해 elemental As 상태가 증가함을 알 수 있었다.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.6 no.3
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• pp.919-940
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• 2012

Video on Demand (VOD) is a multimedia service which allows a remote user to select and then view video at his convenience at any time he wants, which makes the VOD become an important technology for many applications. Numerous periodic VOD broadcasting protocols have been proposed to support a large number of receivers. Broadcasting is an efficient transmission scheme to provide on-demand service for very popular movies. This paper proposes a new broadcasting scheme called Popularity Cushion Staggered Broadcasting (PCSB). The proposed scheme improves the Periodic Broadcasting (PB) protocols in the latest mobile VOD system, which is called MobiVoD system. It also, reduces the maximum waiting time of the mobile node, by partitioning the $1^{st}$ segment of the whole video and storing it in the Local Media Forwarder (LMF) exactly in the Pool of RAM (PoR), and then transmitting them when the mobile nodes miss the $1^{st}$ broadcasted segment. The results show that the PCSB is more efficient and better than the all types of broadcasting and caching techniques in the MobiVoD system. Furthermore, these results exhibits that system performance is stable under high dynamics of the system and the viewer's waiting time are less than the previous system.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2004.11a
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• pp.199-202
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• 2004

NFGM(Nano-Floating Gate Memory) is a very prospective candidate memory for the next generation with MRAM, PRAM, PoRAM. Among these memory devices for the next generation, NFGM has a lot of merits such as a simple low cost fabrication process, improved retention time, lower operating voltages, high speed program/erase time and so on. Therefore, many intensive researches for NFGM have been performed to improve device performance and reliability, which depends on the ability to control particle size, size distribution, crystallity, areal particle density and tunneling oxide quality. In this paper, we investigate the researches for NFGM up to recently.

• Journal of Soil and Groundwater Environment
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• v.15 no.4
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• pp.46-52
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• 2010

Acid mine drainage occurs when sulfide minerals are exposed to an oxidizing environment. The objective of this study was to inhibit the oxidation of pyrite by applying various coating agent such as $KH_2PO_4$, MgO and $KMnO_4$ over its surface as an oxidation inhibitors. Experiments were conducted for 8 days to test the feasibility of oxidation inhibitors. The optimal condition of coating agent for standard pyrite and IK mine was the combination of 0.01M $KH_2PO_4$, 0.01M NaOAc and 0.01M NaClO. Otherwise, for YD mine the combination of 0.01M $KMnO_4$, 0.01M NaOAc and 0.01M NaClO. The $SO_4^{2-}$ reduction efficiency of pyrite, IK and YD mine samples was 70, 92 and 84%, respectively. For 8 days, no significant increase of $SO_4^{2-}$ from pyrite sample coated with inhibitor was observed. The pH of solution remains in between 4 to 6 for the reaction conditions.

• Journal of Korean Library and Information Science Society
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• v.25
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• pp.405-439
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• 1996

During his reign, Kwang-Hae-Kun has done various works to promote literature and book acquisition. Among those works is the establishment of a special office called 'Tok Seo Dang' as he was enthroned in 1608, though it was demolished in 1622. And 'Seo Chuk Kyo In To Kam' was built to recover the scattered and lost books. He encouraged the people to collect and publish books by rewarding those who were engaged in a sort of library works. Their primary responsibility was to collect rare and essential resources, seek the material even in China and publish them using metal printing type. They even sought the diaries and newsletters which the individuals kept at their house. The collected materials were first copied and then kept in 'Shilok' shrine. Among the imported books are Dae Myung Hoi Chon, Chon Choo Sa Chon, Tong Kam Chan Yo, Du Si Tong Chon, Ok Hae, Mun Seon, Hak Hae, Lim Geo Man Rok and some were without titles. Majority of the compiled materials were medical books and geographies like Shin Cheung Tong Kak Yeu Chi Seung Ram, Tong Eui Po Kam, etc. Because of this strenuous effort, they were able to collect and retrieve lots of books and materials between 1608 and 1623. Majority of the published books were of Confucianism(13) which were followed by Political and Legal items(5), Historical documents(3), literature (3), etc. Regarding our library history, one should never forget Kwang-Hae-Kun's significant and remarkable contribution to it.

• Journal of the Korea Computer Graphics Society
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• v.17 no.1
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• pp.17-24
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• 2011

In Computer Graphics, interaction between a particle-based fluid and a rigid body is important. In General, this interaction has been simulated in a discrete environment. As a result, there have been lots of errors. The larger the time step is used, the bigger the error is. This paper describes how to minimize the error in a discrete environment. To be specific, the collision handling method is that estimates particle collision using a signed distance function increases continuously according to space. At the time a fluid particle and a rigid body model collide, the exact collision time and the position is estimated. Through this, we propose the method how to be simulated the interaction between a fluid and a rigid body model as a continuous environment.

• Journal of the Korean Home Economics Association
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• v.37 no.1
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• pp.133-143
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• 1999

Originally, ancestral rites is a ceremony to pay filial piety to ancestors continuously even though they died, and this is a startingpoint based on the thought of paying respect to ancestors and 'root consciousness' which Korean people have. In the earliest days, Korean people worshipped nature and the sacrificial rituals were performed mainly for the fods of the skies and the earth. After the end-Koryeo Era introduced [Juja-Garye]ancestrial rites of forefather in home generalized. By the way, the foods for ancestrial rites on the original literature centering the [Sa-Rye-Pyon-Ram]are as follows: raw meat(saeng: 牲), rice and broth(ban, gaeng: 飯羹), fruits(果), slice meats(po: 脯), salted dry fish(jaban(佐飯), rice punch(sikhye: 食醯), soup(tang: 湯), fish and meat, roasts beef (jeok: 炙), roast vegetable(sookchae: 熟菜), rice cake(pyon: 餠), noodles(麵), soy(醬), Kimchi(沈菜), drink(酒), green tea(cha: 茶) etc. Today, ancestral rites, basically with this conception, has a function to bind the family and relatives as one. But as double income family are increasing, most housewives have heavy burden mentally and financially to prepare the food for the ancestral. The foods for ancestral rites can be said a way to express the internal true heart, and a basic medium to practice the filial piety. Many documents let us know that a few days before the ancestral rites, we should prepare the food for it with careful and pious attitude. And, they stress that our sincere attitude in preparing food is important rather than its quantity. In this industrial society, we have lots of difficulty preparing and observing the same service as it in the traditional socity. But I think that housewives can be freed from the burden they have to some degree when they realize what the true meaning of ancestral rites is and that the food for it plays a role an external expression.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.28 no.6B
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• pp.731-741
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• 2008

Previous studies on the numerical simulation at the tidal reach of Han River tend to restrict downstream boundary as Jeon-ryu station due to difficulties in gaining cross section data and tidal elevation values at Yu-do. But, in this study, geometries beyond the confluence of Gok-reung stream and Im-jin River are constructed based on the numerical sea map; tidal elevation at the downstream boundary, Yu-do is estimated by harmonic analysis of In-cheon tide gage station so that hydrodynamic and diffusion behavior have been analyzed. The domain ranging from Shin-gok submerged weir to Yu-do is selected (which is 36.8 km in length). RMA-2 and RAM4 developed by Il Won Seo (2008) are applied to simulate flow and diffusion behavior, respectively. Numerical results of flow characteristic are compared with the measured data at Jeon-ryu station. Simulation is carried out from June 23 to 25 in 2006 on the ground that hydrologic data is satisfactory and tidal difference is huge during that period. The result shows that reverse flow occurs 5 times according to the tidal elevation at Yu-do and the maximum reverse flow is observed up to Jang-hang IC, which is 32.9 km in length. Also analysis is focused on the process of generation and disappearance of reverse flow, the distribution of water surface elevation and velocity along the maximum velocity line, and the transport of nonconservative pollutant. Pollutant injected from Gul-po stream spreads widely across the river; however, the size of BOD cloud entering from Gok-reung stream is relatively small because water depth at the mid and left side becomes deeper and maximum velocity occurs along the right bank so that transverse mixing is completed quickly. Finally, mixing characteristic of horizontal salinity distribution is obtained by estimating the salinity input with analytical solution of 1D advection-dispersion equation.

• Journal of Life Science
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• v.24 no.9
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• pp.988-994
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• 2014

The effluents of chemical and petroleum industries often contain non-biodegradable aromatic compounds, with phenol being one of the major organic pollutants present among a wide variety of highly toxic organic chemicals. Phenol is toxic upon ingestion, contact, or inhalation, and it is lethal to fish even at concentrations as low as 0.005 ppm. Phenol biodegradation has been studied in detail using bacterial strains. However, these microorganisms suffer from substrate inhibition at high concentrations of phenol, whereby growth is inhibited. A phenol-degrading bacterium, P21, was isolated from oil-contaminated soil. The phenotypic characteristics and a phylogenetic analysis indicated the close relationship of strain P21 to Rhodococcus pyridinovorans. Phenol biodegradation by strain P21 was studied under shaking condition. The optimal conditions for phenol biodegradation by strain P21 were 0.09% $KNO_3$, 0.1% $K_2HPO_4$, 0.3% $NaH_2PO_4$, 0.015% $MgSO_4{\cdot}7H_2O$, 0.001% $FeSO_4{\cdot}7H_2O$, initial pH 9, and $20-30^{\circ}C$, respectively. When 1,000 ppm of phenol was added to the optimal medium, the strain P21 completely degraded it within two days. Rhodococcus pyridinovorans P21 could grow in up to 1,500 ppm of phenol as the sole carbon source in a batch culture, but it could not grow in a medium containing above 2,000 ppm. Moreover, strain P21 could utilize toxic compounds, such as toluene, xylene, and hexane, as a sole carbon source. However, no growth was detected on chloroform.