• KSII Transactions on Internet and Information Systems (TIIS)
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• v.10 no.10
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• pp.4933-4956
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• 2016

Use-After-Free (UAF) is a common lethal form of software vulnerability. By using tools such as Web Browser Fuzzing, a large amount of samples containing UAF vulnerabilities can be generated. To evaluate the threat level of vulnerability or to patch the vulnerabilities, automatic deduplication and exploitability determination should be carried out for these samples. There are some problems existing in current methods, including inadequate pertinence, lack of depth and precision of analysis, high time cost, and low accuracy. In this paper, in terms of key dangling pointer and crash context, we analyze four properties of similar samples of UAF vulnerability, explore the method of extracting and calculate clustering eigenvalues from these samples, perform clustering by fast search and find of density peaks on a large number of vulnerability samples. Samples were divided into different UAF vulnerability categories according to the clustering results, and the exploitability of these UAF vulnerabilities was determined by observing the shape of class cluster. Experimental results showed that the approach was applicable to the deduplication and exploitability determination of a large amount of UAF vulnerability samples, with high accuracy and low performance cost.

• Applied Chemistry for Engineering
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• v.19 no.3
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• pp.322-325
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• 2008

3,3-Dimethyl-1-butene ($C_6H_{12}$) monomer was deposited using a plasma-enhanced chemical vapor deposition (PECVD) instrument. The more the R.F. power/pressure ratio in FT-IR spectrum, the less the hydrogen quantity and the dangling bond in amorphous carbon films observed so that the mechanical property of the films are improved related to the density. Also, with the increase D peak in Raman spectrum is increased and the ring structure's films are produced. According to these results, hardness and modulus are 12 GPa and 85 GPa, respectively. The refractive index (n) and extinction coefficients (k) of the deposited films are increased with the increase in a power/pressure ratio.

• Proceedings of the Korean Information Science Society Conference
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• 2003.04c
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• pp.476-478
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• 2003

1-Base의 non Watson-Crick 결합과, Dangling end(결합이 이루어진 두 개의 DNA strand 중 한쪽 끝이 다른 쪽 끝보다 짧은 경우)를 허용하는 nearest-neighbor model을 사용하여 DNA/DNA Hybridization 예측 시스템을 구현하였다. DNA 컴퓨팅을 기존의 실리콘 컴퓨터를 이용하여 접근하는 이러한 방법은 좀 더 효율적인 분자 알고리즘의 개발과 DNA 컴퓨팅에 사용될 수 있는 더욱 신뢰성 있는 DNA 시퀀스의 설계에 도움을 줄 수 있을 것이다.

• Proceedings of the Korean Information Science Society Conference
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• 2003.10b
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• pp.772-774
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• 2003

DNA/DNA의 연쇄 결합 반응에 대한 시뮬레이션을 열역학적 데이터를 이용하여 구현하였다. 1-Base의 non Watson-Crick 결합과, dangling end(결합이 이루어진 두개의 DNA strand 중 한쪽 끝이 다른 쪽 끝보다 길거나 짧은 경우)를 허용하는 nearest-neighbor model을 사용하여 구현된 이 모델에서는 한번의 hybridization만을 예측하는 것이 아니라 연속적인 결합 반응의 시뮬레이션이 가능하다. 이를 통해서 분자 알고리즘의 설계와 검증이 가능할 뿐만 아니라, cross-homology의 검사를 통한 시퀀스의 검증까지도 가능하다. 이러한 in silico 에서의 접근 방식은 효율적인 분자 알고리즘의 개발과 신뢰성 있는 시퀀스의 설계에 도움이 될 수 있다.

• Proceedings of the Korean Vacuum Society Conference
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• 1999.07a
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• pp.64-64
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• 1999

다결정 실리콘-게르마늄(poly-SiGe)은 태양전지 및 TFT-LCD와 같은 소자 응용에 있어서 중요하게 연구되고 있는 물질이다. 우리는 수소화된 비정질 실리콘-게르마늄 (a-Si1-xGex:H) 박막을 증착시키고 고상결정화시키며 XRD(x-ray diffraction) 및 ESR (electron spin resonance) 측정을 수행하였다. PECVD 증착가스는 SiH4과 GeH4가스를 사용하였고 Ge의 성분비는 x=0.0, 0.1, 0.5 정도로 조절되었다. 기판은 Corning 1737 glass를 사용하였고, 기판 온도는 20$0^{\circ}C$ 이었다. 증착압력과 r.f. 전력은 각각 0.6Torr와 3W이었다. 증착된 SiGe 박막은 고상결정화를 위해 $600^{\circ}C$ N2 분위기에서 가열되고, 그에 따른 XRD 및 ESR spectrum의 변화를 관찰하였다. ESR 측정은 X-band 그리고 상온에서 행해졌다. 먼저 XRD 측정으로부터 박막의 고상결정화 정도를 알 수 있었고, 고상결정화 과정이 초기 핵형성 단계와 결정화 단계, 그리고 더 이상 결정화가 일어나지 않는 완료 단계로 구분될 수 있음을 보여주었다. X값이 증가함에 따라 결정화 시간은 훨씬 단축되었다. ESR로 측정된 스핀 밀도는 a-Si1-xGex:H 박막이 처음 가열됨에 따라 전체적으로 크게 증가했다가, 결정화가 일어나면서 다시 감소하여 나중에는 거의 변화가 없었다. ESR 신호의 초기 증가는 수소 이탈에 의한 dangling bond의 증가에 기인하며, 다음 단계의 감소 및 안정 상태는 결정화에 따른 결정경계 영역의 감소와 결함들의 안정성에 기인하는 것으로 생각된다. 그러나 흥미로운 것은 Si1-xGex 합금의 경우 가열시간이 증가됨에 따라 Si-db(Si-dangling bond)와 Ge-db에 의한 신호가 서로 분리되어 나타났으며, 이 Si-db 스핀 밀도와 Ge-db 스핀밀도의 변화정도는 x값에 크게 의존함을 보여준 것이다. 즉 순수한 a-Si:H의 경우 Si-db 의 스핀밀도의 증가시간은 4시간 정도였고, 그리고 다시 감소하였으며, x=0.1 인 박막에서 Si-db와 Ge-db의 변화 시간은 순수 S-db 변화의 경우와 거의 유사하였다. 그러나 x=0.5 샘플에서는 Si-db의 변화가 빨라져서 0.1 시간 안에 증가되었고, Ge-db의 변화는 더 빠르게 수 분 동안에 증가 된후 다시 감소하였다. 이것은 수소의 Si에 대한 친화력 뿐 만아니라 Si-H과 Ge-H 결합에너지가 주위 원자들의 구성에 크게 영향받을 수 있는 가능성을 제시해준다.

• Applied Chemistry for Engineering
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• v.10 no.3
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• pp.354-361
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• 1999

The films annealed after physical deposition of titanium and chemical deposition of amorphous silicon by plasma were formed Si-rich titanium silicide with a good quality of crystallinity and had the various lattice structures due to orientation of lattices for epitaxy growth during annealing process. Band gap of the titanium silicide had 1.14~1.165 eV and the films annealed after chemical deposition of a-Si:H by plasma were influenced by a-Si and the dangling bond offered by desorption of hydrogen. Urbach tail ($E_0$) of the films annealed after physical deposition of Ti was nearly constant within a range of 0.045~0.05 eV, and the number of defect in films annealed after chemical deposition of a-Si:H by plasma was about 2~3 times more than that in annealed Ti/Si films.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.24 no.1
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• pp.41-45
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• 2014

We have investigated the passivation property of $SiN_x$ and $SiO_2$ thin films formed using various process conditions for the application of crystalline Si solar cells. An increase in the thickness of $SiN_x$ deposited using plasma enhanced chemical vapor deposition (PECVD) led to the improvement of passivation quality. This could be associated with the passivation of Si dangling bonds by hydrogen atoms which were supplied during PECVD deposition. The $SiO_2$ thin films grown using dry oxidation process exhibited better passivation behavior than those using wet oxidation process, implying the dry oxidation process was more effective in the formation of high quality $SiO_2$ thin films. The relative effective life time gradually decreased with increasing dry oxidation temperature. Such a degradation of passivation behavior could be attributed to the increase in interface trap density caused by thermal damages.

• Journal of the Korean Chemical Society
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• v.40 no.4
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• pp.264-272
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• 1996

Cluster models of the Υ-Al2O3(111) and the Pt(111) surfaces have been used in an atom superposition and electron delocalization molecular orbital study of interfacial bond strengths between them. The reduced extents for Al3+ are due to the ratio of oxygen to aluminum atoms. The greater the reduced extent for Al3+ is, the stronger the binding energy is to Pt atoms in a cluster. The oxygen-covered surfaces of Υ-Al2O3(111) are shown to bind more weakly to Pt atoms, while the binding to the oxygen-covered surface formed under oxidizing conditions of Pt atoms is strong. The interfacial bond of platinum-alumina may be possible by a charge-transfer mechanism from the platinum surface to the partially empty O-2p band and Al3+ dangling surface orbital.

• Journal of Sensor Science and Technology
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• v.12 no.5
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• pp.218-224
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• 2003

The devices of n-channel poly silicon thin film transistors(TFTs) hydrogenated by plasma, $H_2$ and $H_2$/plasma processes are fabricated. The carriers sensitivity characteristics are analyzed with voltage bias stress at the gate oxide. The parametric sensitivity characteristics caused by electrical stress conditions in hydrogenated devices are investigated by measuring the drain current, threshold voltage($V_{th}$), subthreshold slope(S) and maximum transconductance($G_m$) values. As a analyzed results, the degradation characteristics in hydrogenated n-channel polysilicon thin film transistors are mainly caused by the enhancement of dangling bonds at the poly-Si/$SiO_2$ interface and the poly-Si grain boundary due to dissolution of Si-H bonds. The generation of traps in gate oxide are mainly dued to hot electrons injection into the gate oxide from the channel region.

• Proceedings of the Korean Vacuum Society Conference
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• 2016.02a
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• pp.101.1-101.1
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• 2016

Van der Waals (vdW) heterostructures built from two-dimensional layered materials provide an unprecedented opportunity in designing new material systems because the lack of dangling bonds on the vdW surfaces enables the creation of high-quality heterointerfaces without the constraint of atomically precise commensurability. In particular, the ability to build artificial heterostructures, combined with the recent advent of transition metal dichalcogenides, allows the fabrication of unique semiconductor heterostructures in an ultimate thickness limit for fundamental studies as well as novel device applications. In this talk, we will present the characterization of the electronic and optoelectronic properties of atomically thin p-n junctions consisting of vertically stacked WSe2 and MoS2 monolayers. We observed gate-tunable diode-like current rectification and a photovoltaic response across the p-n interface. Unlike conventional bulk p-n junctions, the tunneling-assisted interlayer recombination of the majority carriers is responsible for the tenability of the charge transport and the photovoltaic response. Furthermore, we will discuss the enhanced optoelectronic characteristics in graphene-sandwiched vdW p-n junctions.