• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2001년도 가을 학술발표회 논문집
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• pp.835-840
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• 2001

The new approach is a kind method of restoring temporary defect. Here, it is important for the defect not to occur problems of both local effect and global system. A basic concept is that it measures remaining prestress of PSC structures during the defect is restored. This study suggested new approach for measurement of remaining prestress. Two important results are obtained. First, safety problems, local stress concentration and global system, are very satisfied. Second, measurement value exists within error bound $\pm$ 1% in comparison with known value.

• 한국재료학회지
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• 제11권1호
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• pp.55-60
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• 2001

고 에너지 (1.5 MeV) 이온 주입된 Boron의 농도와 silicon 기판의 초기 산소 농도의 변화에 따라 silicon기판에 형성된 결정 결함 및 금속 불순물의 Gettering 효율에 대하여 DLTS(Deep Level Transient Spectroscopy), SIMS(Secondary ion Mass Spectroscopy), BMD(Bulk Micro-Defect) analysis 및 TEM (Transmission Electron Microscopy)을 이용하여 연구하였다. 이온 주입 전후의 DLTS 결과를 확산로 및 RTA를 이용한 열처리 전후의 DLTS 결과와 비교할 때 이온 주입 전 시편에서 볼 수 있는 공공에 의한 깊은 준위는 열처리 온도의 증가에 따라 금속 불순물과 관련된 깊은 준위로 천이함을 알 수 있다. 또한 고온 열처리의 경우, 초기 산소 농도가 높을수록 깊은 준위의 농도가 감소함을 볼 때 초기 산소 농도가 높을 수록 gettering 효율 측면에서 유리한 것으로 사료된다

• 한국재료학회지
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• 제11권7호
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• pp.615-621
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• 2001

본 연구에서는 고변형된 이중 에피층에서 두 가지 종류의 반원 전위 루프 ($60^{\circ}$및 쌍격자 전위)의 생성 속도물 예측하는 모델을 제안한다. 모델링 시, 에피층 표면에서 발생하는 결함과 이곳에 집중되는 응력 효과를 고려하였으며, Matthew의 식을 발전시켜 에피층 두께에 따른 잔류 변형율을 변수로 사용하였다. 모델링을 통한 계산 결과에 의하면, 응력 집중 현상은 고변형된 이종에피층에서 전위 및 결정 결함 현상을 설명하는 데 매우 중요하였다. 또한,본 연구를 퉁하여, 응력 집중 현상이 에피층 성장 초기에 생성되는 전위 형태를 결정하는 주요한 인자 중 하나임을 단면 투과 전자 현미경 결과와의 비교를 통해 확인할 수 있었다.

• Journal of Magnetics
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• 제16권4호
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• pp.332-336
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• 2011

We studied the effect on the electronic and magnetic properties of the N defect in clean and Cu-doped wurtzite III-nitrides by using the first-principles calculations. When it is doped two Cu atoms in the nearest neighboring sites, the system of AlN, GaN, or InN with the N vacancy is energetically more favorable than that without the N vacancy site. When the Cu concentration increases, the total magnetic moment of a supercell becomes small. The ferromagnetism of Cu atom is very low due to the weak 3d-3d coupling. It is noticeable that the spin-exchange interaction between the Cu-3d and N defect states is important.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2005년도 하계학술대회 논문집 Vol.6
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• pp.149-150
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• 2005

Thyristor breakdown voltage variation acceleration aging test was investigated. The breakdown voltage was deceased after 1000 hours acceleration aging test. It temperature rising caused by electric field concentration at the edge beveling region of the thyristor was confirmed using Silvaco device simulation. The local temperature rising is driving force for the defect propagation. Consequently, propagated defects of the beveling region seems to decrease thyristor's breakdown voltage.

• 대한기계학회논문집A
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• 제31권3호
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• pp.344-354
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• 2007

The objective of this study is to investigate the effect of arbitrarily located defect around the circular hole in the aircraft structural material such as Al/GFRP laminates and monolithic Al alloy sheet under cyclic bending moment. The fatigue behavior of these materials may be different due to the defect location. Material flaws in the from of pre-existing defects can severely affect the fatigue crack initiation and propagation behavior. The aim of this study is to evaluate effects of relative location of defects around the circular hole in monolithic Al alloy and Al/GFRP laminates under cyclic bending moment. The fatigue behavior i.e., the stress concentration factor($K_t$), the crack initiation life($N_i$), the relationship between crack length(a) and cycles(N), the relationship between crack growth rate(da/dN) and stress intensity factor range(${\Dalta}K$) near a circular hole are considered. Especially, the defects location at ${\theta}_1=0^{\circ}\;and\;{\theta}_2=30^{\circ}$ was strongly effective in stress concentration factor($K_t$) and crack initiation life($N_i$). The test results indicated the features of different fatigue crack propagation behavior and the different growing delamination shape according to each location of defect around the circular hole in Al/GFRP laminates.

• Current Photovoltaic Research
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• 제4권3호
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• pp.124-129
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• 2016

Recently industry has voiced a need for optimally designing the production process of low-cost, high-quality ingots by improving productivity and reducing production costs with the Czochralski process. Crystalline defect control is important for the production of high-quality ingots. Also oxygen is one of the most important impurities that influence crystalline defects in single crystals. Oxygen is dissolved into the silicon melt from the silica crucible and incorporated into the crystalline a far larger amount than other additives or impurities. Then it is eluted during the cooling process, there by causing various defect. Excessive quantities of oxygen degrade the quality of silicone. However an appropriate amount of oxygen can be beneficial. because it eliminates metallic impurities within the silicone. Therefore, when growing crystals, an attempt should be made not to eliminate oxygen, but to uniformly maintain its concentration. Thus, the control of oxygen concentration is essential for crystalline growth. At present, the control of oxygen concentration is actively being studied based on the interdependence of various factors such as crystal rotation, crucible rotation, argon flow, pressure, magnet position and magnetic strength. However for methods using a magnetic field, the initial investment and operating costs of the equipment affect the wafer pricing. Hence in this study simulations were performed with the purpose of producing low-cost, high-quality ingots through the development of a process to optimize oxygen concentration without the use of magnets and through the following. a process appropriate to the defect-free range was determined by regulating the pulling rate of the crystals.

• 한국세라믹학회지
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• 제28권2호
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• pp.141-145
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• 1991

LEC법으로 성장된 GaAs의intrinsic defect에 의해서 형성된electron 및 hole trap의 농도와 성장시의 melt stoichiometry 와의 정량적 상관 관계를 DLTS법을 이용하여 분석하였다. EL2는 melt중 As의 분을 ([As]/{[As]+[Ga]})이 1.5에서 0.42까지 변하면 그 농도가 $10^{16}cm^{-3}$에서 $10^{11}cm^{-3}$정도로 감소되며, 이때 분율이 0.46 이하에서는 그 이상에서보다 As의 감소에 따라 급격히 감소하였다. 68meV 및 77/220meV의 경우는 As의 분율이 감소하면 증가하여 각각 $10^{15}cm^{-3}$ 및 $10^{14}cm^{-3}$ 정도의 농도를 가진다. 따라서 이 trap들은$GS^{AS}$와 관련된 defect들에 의해서 형성되었음을 알 수 있다.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2000년도 영호남학술대회 논문집
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• pp.222-232
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• 2000

The relationship between carrier electron concentration(n) and atmosphere oxygen partial pressure($P_{O_2}$ for pure ZnO calculated by the mass-action law, well-known as n ${\propto}P^{-1/m}_{O_2}$ where m = 4 or 6 for the single or the double ionization of the native donor defects due to its nonstoichiometry, respectively, is found in competition with the calculation result on the basis that the total defect concentration is the sum of those of unionized and ionized defects. Definitively, it is found inconsistent with the calculation result by employing the Fermi-Dirac(FD) statistics for their ionization processes. By application of the FD statistics law to the ionization while assuming the defect formation is still ruled by the mass-action law, the calculation results shows the concentration is proportional to $P^{-1/2}_{O_2}$ whenever they ionize singly and/or doubly. Conclusively we would like to propose the new theoretical relation n ${\propto}P^{-1/m}_{O_2}$ because the ionization processes of donors in ZnO should be treated with the electronoccupation probability at localized quantum states in its forbidden band created by the donor defects, i.e. the FD statistics

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2004년도 하계종합학술대회 논문집(2)
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• pp.485-488
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• 2004

As scaling down the cell channel length, the increment of B concentration in channel region is inevitable to overcome the punch-through, especially in flash memory cell with 90nm technology. This paper shows that the high dose ion implantation in channel cause the Si defect. which has been proved to be the major cause of the tailed Vth in distribution. And also mechanical stress due to SiN-anneal process can induce the Si dislocation. and get worse it. With decreasing the channel implantation dose, skipping the anneal and reducing the mechanical stress, Si defect problem is solved completely. We are verify first that the optimization of B concentration in channel must be certainly considered in order to improve Si defect. It is also certainly necessary to stabilize the distribution of cell Vth in the next generation of flash memory.