• Journal of the Optical Society of Korea
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• v.10 no.2
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• pp.86-90
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• 2006

The external feedback effect on the relative intensity noise (RIN) characteristics of blue InAlGaN laser diode has been analyzed taking into account the spontaneous emission noise and the injection current for the high frequency modulation. A Langevin diffusion model was exploited to characterize its relative intensity noise. The simulation parameters were quantitatively evaluated from the optical gain properties of the InAlGaN multiple quantum well active regions by using the multiband Hamiltonian for the strained wurtzite crystals. The extracted parameters were then applied to the rate equations taking into account the external feedback and the high frequency modulation current. The RIN characteristics were investigated to optimize the low frequency laser diode noise characteristics.

• Proceedings of the IEEK Conference
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• 2006.06a
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• pp.567-568
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• 2006

We investigate the structures and the formation energy of inversion domain boundaries (IDBs) using the Tersoff empirical potential. Four kinds of IDBs ( A and B types for IDB* and Holt ) are considered. The IDBs with A type are energetically favorable compared to B type with the structural instability. The IDB* is also more stable than the Holt type in spite of fourfold and eightfold rings of bonds. We calculate the atomic configurations of the Holt IDBs induced by the interactions of the IDB* with the stacking faults $I_1$ and $I_2$. The stacking fault $I_2$ interacted with $I_1$ on the IDB induces the structural transformation from IDB* to Holt type.

• Korean Journal of Veterinary Service
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• v.25 no.1
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• pp.97-103
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• 2002

Infectious bronchitis(IB) is a viral disease in which continued evolution of the virus is of paramount importance for annual endemics and epidemics in chickens. Since the isolation of IB viruses(IBVs) in the 1930s, over 50 serotypes or variants have been reported worldwide. Continuing evolution is most prominent in the suface glycoproteins of IBV but also occurs in other parts of the genome. This genetic variability results from accumulation of molecular changes that can occur by a number of different mechanisms including genetic drift (point mutations) and genetic shift(RNA recombination). GA98 is a new serotype of IBV identified recently in the United States. In this paper, the evolutionary trend of IBV will be discussed using GA98 serotype as a model.

• Journal of the Korean Institute of Landscape Architecture
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• v.18 no.3 s.39
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• pp.137-141
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• 1990

This study was carried out to investigate the propagation methods of the Rhododendron micranthum as a landscape plant The results obtained are as follows :　1. The optimum temperature for seed germination was $20^{\circ}C$, and the seed germination needs light. 2. GA and thiourea did not affect the seed germination under light, but GA gad substitutive effect. 3. 87% and over of germination rates were obtained in room temperature and $5^{\circ}C$ dry storages. 4. The rooting rate was high on sandy loam, vermiculite, and vermiculite 50%+sand 50%, at softwood and hardwood cutting(hardwood ; 45~48%, softwood ; 45~48%). 5. The significant effects on rooting were found with the treatment of NAA 500~2000ppm.

• ETRI Journal
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• v.13 no.4
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• pp.25-34
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• 1991

The stability and the electronic structure of $In_0.5$.$Ga_0.5$P-based superlattices are examined through self-consistent ab initio pseudopotential calculations. A chalcopyrite-like structure is found to be the lowest energy state over (001) and (111) monolayer superlattices (MLS). Our calculations indicate that all the ordered structures in bulk form are unstable against phase segregation into binary constituents at T = 0 while for epitaxial growth, the chalcopyrite phase is stabilized. The fundamental band gaps of the ordered structures are found to be direct and smaller than that of disordered alloys. The lowering of the band gap is explainable by band folding and pushing effects. We find the reduction of the band gap to be largest for the (111) MLS.

• ETRI Journal
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• v.13 no.4
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• pp.52-57
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• 1991

We fabricated very high. speed PIN Photodiode module for the application of high speed optical receiver. OMVPE was used for the growth of InP layer on InGaAs absorption layer. The structure was the combination of mesa and planartype. Fabrication procedure was more complicated than simple mesa or simple planar type structure because we used semiinsulating InP substrate in order to reduce stray capacitance. The results at-5V were as follows : dark current was less than 1nA, capacitance was 0.55pF, and cutoff frequency was above 3GHz, and rise and fall time was about 100ps.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• v.9 no.1
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• pp.985-989
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• 2005

본 논문에서는 비정질 반도체 및 절연체의 etching을 RIE를 사용하여 etching 조건을 결정하는 요인(chamber pressure, gas flow rate, rf power, 온도 등)들을 변화시켜 실험하였고, gas는 비정질 실리콘 박막의 reactive ion etching에 주로 사용되는 $CF_4,\; CF_4+O_2,\;CCl_2F_2,\;CHF_3\;gas$ 등을 사용하였다. 여기서 실리콘 박막의 식각은 $CF_4,\;CCl_2F_2,\;gas$를 그리고 insulator 막인 SiNx 박막의 식각은 $CF_4+O_2,\;CHF_3\;gas$를 사용하였다. 특히 $CCl_2F_2$ gas는 insulator 막인 SiNx 박막과의 식각 selectivity가 6:1로서 우수하기 때문이다. 정확한 control에 의해 높은 수율 (Yield) 을 얻을 수 있어 cost를 절감할 수 있다.

• Proceedings of the KIEE Conference
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• 1996.07b
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• pp.1389-1391
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• 1996

In this paper, we applies two methods - Genetic Algorithm(GA) and $A^*$ Algorithm - to find the optimal path in route guidance system. Under the assumption that the traveling costs of each link are given, the task to find the optimal path becomes very complicated problem if the number of nodes or links increase. Two well-known algorithms are modified to resolve the problem and the preliminary demonstration show both optimistic result and needs to improvement.

• Journal of Korean Institute of Industrial Engineers
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• v.27 no.2
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• pp.140-149
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• 2001

The paper discusses the problem of finding the Origin-Destination(O-D) shortest paths in internodal transportation networks with time-schedule constraints. The shortest path problem on the internodal transportation network is concerned with finding a path with minimum distance, time, or cost from an origin to a destination using all possible transportation modalities. The time-schedule constraint requires that the departure time to travel from a transfer station to another node takes place only at one of pre-specified departure times. The scheduled departure times at the transfer station are the times when the passengers are allowed to leave the station to another node using the relative transportation modality. Therefore, the total time of a path in an internodal transportation network subject to time-schedule constraints includes traveling time and transfer waiting time. In this paper, a genetic algorithm (GA) approach is developed to deal with this problem. The effectiveness of the GA approach is evaluated using several test problems.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.18 no.6
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• pp.152-157
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• 2004

In this paper, an optimum design method is presented for BLDC moor magnet using genetic algorithm(GA) and response surface method(RSM). The cogging torque is calculated by finite element method for the designs obtained by GA and RSM. The results are compared and discussed for the simulation time and the cogging torque.