The characteristics of temperature variation for laser diode welding system have been analyzed with numerical investigation. The laser diode is assembled with a cap and stem by projection welding. Resistance heat, in this process, is generated by electric current at the contact surface between cap and stem within a very short time. Temperature variation of laser diode is largely affected by the welding time and the heat generated from the surface. Maximum temperature of each component in the laser diode should be lower than the melting point except for cap and stem in order to prevent welding defect. Temperature distribution of each component in the laser diode is also affected by thermal conduction mechanism. Welding defect near the insulator occurs when the resistance heat is high. Appropriate resistance heat supply to the laser diode was about 400W. The results from this study could be applicable for optimal design of laser diode welding system.

Numerical modeling has been carried out to analyze thermal characteristics for laser diode welding machine. Laser diode welding machine performance is largely affected by the applied current and welding period. Unsteady thermal characteristics near the laser diode welding cap has been analyzed, and most simulations were performed after applying electrical current for the duration from 0.1 to 0.5 second. Those results from this study could be applicable to the design of optimal operating condition for the laser diode welding machine system.

Currently, dental implants are generally used for reconstruction of oromaxillofacial defects. Implants are widely used in dental and medical fields. The materials of implants are variable such as metals and ceramics. The materials of implants must be have not toxicity and biocompatibility to host and mechanical(physical) strength. Bones must be attached to titanium surface without any other tissues. many researcher's had studied for raising the osseointegration through various method which are including implants designs and materials. It was reported over 95% success ratio. many researcher's study the methods which are enhancing the speed of bone remodelling and osseointegration. Thermo dynamic therapy is one of the method to accelerlate the speed of bone remodelling and osseointegration. Thus it raise stability of implants. The purpose of this study was to evaluate the effect of diode laser irradiation for ossoeintegration in implant interface and between the implants threads. 24 New Zealand white rabbits which were about 3kg weight, used for experiment. 2 implant's were implanted every rabbit's tibia. 2 weeks, 4 weeks, 8 weeks after implantation, tissue sample were removed from sacrificed rabbit's tibia. 8 rabbit's were sacrificed every 2, 4, 8 weeks and undecalcified sample were made from tissue sample. We have investigated the undecalcified samples by back scattered electron microscope. We have analysied the length rate and area rate in implant interface and inside the threads. The results were as follows. 2 weeks, 4 weeks, 8 weeks experimental groups which were irradiated low level laser therapy showed rapid bone remodelling than control groups. It was suggested that Initial bone remodelling may be effected by LLLT because of implant bone contact ratio between 4th weeks and 8th weeks had no siginifant difference. Initial bone remodelling may be more influenced than later bone remodelling by LLLT because of new bone formation area ratio between implant threads had no significant differences during 4th to 8th weeks. According to above results, low level laser irradiation accerlate the new bone formation in implant interface and inside the implants threads at initial stage. there were many factors which are increasing the bone remodelling, because there were many differences between experimental and control groups. Low level laser irradiation were helpful for increasing the initial stage of bone remodelling because of above results.

Currently, implants are widely used in dental and medical fields. Especially dental implants are widely used for reconstruction of oral and maxillofacial defects. Many researcher's had studied for raising the osseointegration through various method. It was reported high success rate. Also they study the enhancing the speed of bone remodelling and osseointegration. Low level laser therapy is introduced one of the methods to accelerate the speed of bone remodelling and osseointegration. The purpose of this study was to evaluate the effect of diode laser irradiation about to raise ossoeintegration. Twenty four New Zealand white rabbits which were about 3Kg were used for experiment. Two implants were implanted same side of rabbits tibia. Diode laser was irradiated 1cm diameter, 0.5 watt power, 1 minute duration at periphery of one of implants. Eight rab b its were sacrificed every 2, 4, 8 weeks, made undecalcified sample. We investigated in the undecalcified samples histological and histomorphometrc analysis by light microscope. The results were as follows. 2 weeks, 4 weeks, 8 weeks experimental groups which were showed rapid bone remodelling than control groups. They showed many difference especially in early healing time. Bone Implant contact rate were 47% in 2 weeks experimental group. 28% in 2 weeks control groups, 82% in 4 weeks experimental groups, 62% in 4 weeks control groups, 98% in 8 weeks experimental groups and 84% in 8 weeks control groups then experimental groups show statistically significant difference(p＜0.05). Bone remodelling area rate inside the implant threads were 49% in 2 weeks experimental groups. 31% in 2 weeks control groups, 90% in 4 weeks experimental groups, 82% in 4 weeks control groups, 99% in 8 weeks experimental groups and 97% in 8 weeks control groups then 2,4 weeks experimental groups show statistically significant difference(p＜0.05). Implant-bone contact length rate and bone remodelling area rate were no significant difference of linear regression equation of control and experimental groups then bone remodelling were different at early healing time but there were no differences of time changes. According to above results, one of the low level lasers diode laser irradiation was effected on the volume of new bone formation in implant interface and between the implants threads. Low level laser irradiation were helpful for initial stage of bone remodelling.

This study was conducted to test the anticancer effect of photodynamic therapy using chlorophyll derivative (9-HpbD-a) and 632nm diode laser. Human SNU 1041 cells were seeded into 96 well plate of 104cells/well and cultured for 24 hours. Cells were washed with media containing various concentration of 9-HpbD-a ranging from Oug/ml to 3.75ug/ml. Then 932 nm diode laser was given at various lasering time setting, and at various starting time after ini tial 24 hours of culture. The treated cells were incubated 48 hours and tetrazolium-based colorimetric(M'IT) assay was done to measure the viability of cells For in vivo study, SNU- 1041 cells were xenografted into the back of nude mouse. When the xenografted tumors grew up to 400-600 mm3, the animals were randomly placed into 4 groups: Group 1 (n=20) , PDT group, interstitial injection of 9-HpbD- a (47 ug/kg) followed by irradiation with 3.2 J/c야 of light 6 hours after then i띠 ection; Group II (n=lO) , irradiation with 3.2 J/crrf of light using diode laser; Group III (n=lO), in terstitial injection of 9-HpbD- a only(47 ug/kg); Group IV (n=lO), normal control group. The viability of cells was de creased with increasing lasering time No significant difference of cell viability was noted by variously delayed starting time of lasering. PDT effects were observed in the xenografted nude mouse model Group IV (no 9-HpbD-a, no laser irradiation) was a control group which showed a continuous tumor growth. Group III (9-HpbD-a i띠 ection only) showed no response, Group II (laser irradiation only) sho￦ed 1 complete remission out of 10 (10%) , Group 1 (9-HpbD-a and laser irradiation) showed 13 cpmplete remission out of 20 (65%) , Group 1 showed significant remission rate, comparing to other groups (p<0.05). This study demonstrated anticancer effect of photodynamic therapy using 9-HpbD-a and 632nm diode laser on human squamous cell carcinoma cell line.

매립형 InGaAnP/InP 레이저 다이오드 제작을 위한 질량 이동 현상의 최적화에 대한 연구를 수행하였다. Double heterostructure 레이저 다이오드 구조의 1차 성장은 액상 에피 성장 장치를 이용하였으며, 메사 에칭하였다. 활성층을 [110] 방향으로 선택적으로 에칭 한 후, 액상 에피 성장 장치를 이용하여 질량 이동 현상을 발생시켜 매립형 구조를 형성시켰다. 질량 이동 현상의 임계온도는 40분간 유지시켰을 때 670˚C로 나타났으며 재현성 있게 질량 이동 현상이 발생하였다. 질량 이동 현상에 의해 성장된 층의 폭은 온도증가에 따라 약간 증가하였다.