• Restorative Dentistry and Endodontics
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• 제22권1호
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• pp.267-277
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• 1997

The purpose of this study was to evaluate the shear bond strength of light-cured glass ionomer cements to dentin surface according to curing time induced by argon laser. In this study, 160 extracted human molars with sound crown were used. The dentin surface of these teeth were exposed with high speed diamond bur under water spray and polished with 120, 320, 400, 800, 1200 grits sand paper. 160 extracted human molars were randomly assigned into four groups (control, experimental 1, 2 & 3) with 40 teeth each. Control group used a visible light curing unit, XL 1000(3M Co., U.S.A) and experimental groups used argon laser($SPECTRUM^{TM}$). And then each group subdivided into two groups (A, B) according to filling materials. Subdivided A group used Fuji II LC(GC Co., Japan), B group used Vitremer(3M Co., U.S.A). The curing units and curing time of each group were as follows : Control group : visible light, 40 seconds Experimental group 1 Experimental group 2 Experimental group 3 : argon laser, 10 seconds : argon laser, 20 seconds : argon laser, 30 seconds The glass ionomer cements were bonded to dentin surface of each specimen. The specimens were stored in 100% relative humidity at 37"c for 7days. And then, the shear bond strength were measured by universal testing machine(Shimatzu Co. Japan) at crosshead speed of 5mm/min and 100kg in full scale and analyzed statistically. The following results were obtained : 1. Experimental group 2-A showed the highest shear bond strength with $9.87{\pm}1.24$ kgf and control group B showed the lowest shear bond strength with $4.08{\pm}0.78$ kgf(P<0.01). 2. The Fuji II LC showed higher shear bond strength with $9.49{\pm}1.24$ kgf than that of the Vitremer with $4.23{\pm}1.24$ kgf. There was significant difference between Fuji II LC and Vitremer(p<0.01). 3. There was no significant differences among experimental groups according to curing time induced by argon laser. 4. There was no significant differences between control group and experimental groups according to curing units.

• Journal of Periodontal and Implant Science
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• 제29권3호
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• pp.577-594
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• 1999

The major cause of periodontal disease is microorganism in the dental plaque. Gingival sulcular fluid, which is exudate released from the tissue near crevicular epithelium is related with inflammation. The purpose of this study was to evaluate the argon laser efficiency between the clinical index and onset of collagenase of gingival sulcular fluid. Material divided 16 patients into 4 groups. The first control was without treatmemt. The second was with just treatment of argon laser, The third was treated by scaling and root planning and the fourth was treated with both scailing and root planning and argon laser. The level of periocheck test, the index of bleeding, and the depth of periodontal pocket were evaluated from for 128 teeth of 64 anterior teeth and 64 posterior teeth. The results were as follows ; 1. In the score of periocheck test, root planing group(group 3) was significantly reduced more than the group without treatment(group 1) and the argon laser treatment(group 2) for results of 3 days and 7 days. But root planing plus argon laser treatment(group 4) in the 7days after experiment, was significantly reduced than no treatment(group 1) and root planing treatment(group 3)(P<0.05), in the 3 days after experiment, was significantly reduced than root planing(group3)(P<0.05). The score of periocheck test to the root planning group(group 3) were significantly reduced between days1, day3 and day7(P<0.05). Root planning plus argon laser group(group 4) were significantly reduced to 1 or 7days and 3 or 7days(P<0.05). The argon laser group(group 2) didn't show any changes. 2. In the case of sulcus bleeding index, the root planning group(group 3) and root planning plus argon laser group(group 4) were reduced more than without treatment group(group 1)(P<0.05) and sulcus bleeding index in the root planning group(group 3) were reduced more than the argon laser group(group 2)(P<0.05). 3. There wasn't any changes of pocket depth between the control and the experiment group as with experiment periods also.

• 대한소아치과학회지
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• 제25권2호
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• pp.368-382
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• 1998

The purpose of this study is to evaluate and compare the results of argon laser for 5 seconds, argon laser for 10 seconds, and visible light for 40 seconds photo-polymerization in compressive strength, microhardness, curing depth, temperature rising during polymerization, and polymerization shrinkage. Hybrid type composite resin(Z-100) and compomer(Dyract) were used to be compared. The compressive strength was measured by an Instron(1mm/min cross head speed) in 60 specimens and the microhardness of the surface was expressed by Vickers Hardness Number(VHN) in 30 specimens. The curing depth was evaluated comparing the different values of upper and lower VHN according to irradiation time and thickness for the light source polymerization in 60 specimens. The temperature rising during photopolymerization was observed by the temperature change with thermocouple sensitizer beneath 40 specimens at the argon laser for 10 seconds and visible light 40 seconds irradiation. The polymerization shinkage was evaluated by calculating the decrease of % volume by using a dilatometer in 30 specimens. The results were as follows ; 1. In the case of compressive strength, the argon laser polymerization groups were higher than visible light group in Z-100 (p<0.05). In Dyract, the argon laser 5 seconds group did not show a significant difference with the visible light 40 seconds group. The argon laser 10 seconds group showed the markedly low value when compared with other groups (p<0.05) 2. In microhardness, Z-100 was better than Dyract when comparing by VHNs (p<0.05); however, there was not a significant difference between two materials in the visible light 40 seconds group and the argon laser 10 seconds group. 3. In the study of curing depth, Z-100 showed the consistent polymerization in argon laser irradiation because there was no difference in the VHN decrease according to the thickness change. Over the thickness control, the results did not show a significant difference between visible light and argon laser group in Z-100; however, in the case of Dyract, the visible light 40 seconds group was better than the argon laser groups(p<0.05). 4. There was a significant difference between the two materials in temperature rising during polymerization (p<0.05), but not a significant difference between irradiation times, 5. There was not a significant difference between the two materials in polymerization shrink age. The argon laser 5 seconds group was smaller than the other groups (p<0.05). It could be concluded that Z-100 polymerization was recommended to use the argon laser for reduction of the irradiation time while Dyract was recommended to use the visible light polymerization.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1995년도 하계학술대회 논문집 C
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• pp.1404-1406
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• 1995

In this paper, argon gas was used for numerical analysis of an arc in a cutting plasma torch driven by constant current. We established nozzle-constricting type torch domain and calculated steady state characteristics of argon arc plasma using the control volume method(CVM). For simplicity, we assumed that the flow field is laminar and the local thermodynamic equilibrium(LTE) prevails in all domain regions. We also neglected cathode-fall and anode-fall effects. Considering magnetic pinch effect and viscosity effect, we solved the momentum equation. Voltage drop in the arc column due to input current was calculated from the temperature field obtained by the energy balance equation.

• Journal of Oral Medicine and Pain
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• 제30권2호
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• pp.277-285
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• 2005

치주질환을 야기하는 세균을 제거하고, 세균집락을 감소시키는 레이저 에너지의 광열적 작용을 이용하여 치주질환의 치료에 대한 효과를 알아보고자, 연세대학교 치과대학병원 구강내과에 내원한 중등도의 치주질환을 가진 환자를 대상으로, 각각 Argon 레이저를 이용한 치은연하 소파술과 통상적인 치은연하 소파술을 시행하여 비교하였다. 시술 전과 시술 1주 후 각각 치은열구액을 채취하여 치주질환의 중요한 원인인 호기성 세균과 혐기성 세균에 대해 배양된 세균 군락수의 변화를 비교하고, 또한 치태지수, 치은지수, 치면열구 출혈지수와 같은 치주질환과 관련된 임상적 지표의 변화를 비교하였다. 연구 결과, 호기성 세균 및 혐기성 세균에 대한 세균 군락 수 비교 시, Argon 레이저를 이용하여 치주치료를 시행한 실험군과 치은연하 소파술을 시행한 대조군 모두 시술 전에 비해 시술 1주 후 세균의 군락 수에 있어서 감소 양상을 나타내었고, 특히 혐기성 세균의 군락 수에 있어서는 통계학적으로 유의한 감소 양상을 나타내었으며(p<0.1), 두 군 사이에 통계학적으로 유의한 차이는 없었다. 또한 치주조직의 상태를 나타내는 지표로서 이용되는 치태지수, 치은지수 및 치은열구 출혈지수의 비교 시 Argon 레이저를 이용하여 치주치료를 시행한 실험군과 치은연하 소파술을 시행한 대조군 모두 시술 전에 비해 시술 1주 후 지수의 감소양상을 나타내었고, 특히 Argon 레이저를 이용한 실험군에서는 치은지수(p<0.1)와 치은열구 출혈지수(p<0.01)가, 치은연하 소파술을 시행한 대조군에서는 치은열구 출혈지수(p<0.01)가 통계학적으로 유의한 감소 양상을 나타내었다. 그러나 두 군 사이에 각각의 지수에 있어서 모두 통계학적으로 유의한 차이는 없었다. 이상의 연구 결과, 중등도의 치주질환의 치료에 있어서 Argon 레이저는 치은연하 소파술을 대신하거나 또는 치은연하 소파술과 병용하여 치료 효과를 더욱 상승시켜주는 유의한 치료법이라고 사료되며, 본 연구 결과 임상적 적용 가능성이 있다고 보여지나, 보다 효과적으로 임상에 적용하기 위해서는 앞으로 충분한 표본의 확보 및 장기적인 예후 관찰을 포함한 더욱 정밀하게 조절된 연구가 필요하리라고 사료된다.

• Journal of Communications and Networks
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• 제13권5호
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• pp.518-524
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• 2011

A high assurance IP encryption (HAIPE) compliant protocol accelerator is proposed for military networks consisting of red (or classified) networks and black (or unclassified) networks. The boundary between red and black sides is assumed to be protected via a HAIPE device. However, the IP layer encryption introduces challenges for bandwidth on demand satellite communication. The problems experienced by transmission control protocol (TCP) over satellites are well understood: While standard modems (on the black side) employ TCP performance enhancing proxy (PEP) which has been shown to work well, the HAIPE encryption of TCP headers renders the onboard modem's PEP ineffective. This is attributed to the fact that under the bandwidth-on-demand environment, PEP must use traditional TCP mechanisms such as slow start to probe for the available bandwidth of the link (which eliminates the usefulness of the PEP). Most implementations recommend disabling the PEP when a HAIPE device is used. In this paper, we propose a novel solution, namely broadband HAIPE-embeddable satellite communications terminal (BHeST), which utilizes dynamic network performance enhancement algorithms for high latency bandwidth-on-demand satellite links protected by HAIPE. By moving the PEP into the red network and exploiting the explicit congestion notification bypass mechanism allowed by the latest HAIPE standard, we have been able to regain PEP's desired network enhancement that was lost due to HAIPE encryption (even though the idea of deploying PEP at the modem side is not new). Our BHeST solution employs direct video broadcast-return channel service (DVB-RCS), an open standard as a means of providing bandwidth-on-demand satellite links. Another issue we address is the estimation of current satellite bandwidth allocated to a remote terminal which is not available in DVBRCS. Simulation results show that the improvement of our solution over FIX PEP is significant and could reach up to 100%. The improvement over the original TCP is even more (up to 500% for certain configurations).

• 한국산업융합학회 논문집
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• 제26권1호
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• pp.87-94
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• 2023

TMCP(Thermo Mechanical Control Process) steel was continuously cast (CC) by varying the argon gas flow rate and vacuum time in the Ruhrstahl Heraeus (RH) refining process. Using the CC specimens, the distribution of the inclusions and the mechanical properties were evaluated. A lot of oxides and Al-O type inclusions were observed. The average Vickers hardness did not show a constant, but showed dispersion in a certain range. The shape and scale parameters of the CC specimen with an argon gas flow rate of 160Nm³ and a vacuum time of 12 minutes was the best. Mechanical properties (tensile strength, yield strength and elongation) were consistent with the Weibull probability distribution analysis results. The impact resistance was the best for CC specimens with an argon flow rate of 140 Nm³ and a vacuum time of 12 minutes. Although the inclusions and mechanical properties of the CC specimens were evaluated according to the argon gas flow rate and vacuum time, these values were no significant difference.

• Journal of Periodontal and Implant Science
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• 제25권3호
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• pp.668-678
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• 1995

In order to evaluate the therapeutic effect of argon laser irradiation on hypersensitive root, 60 mandibular premolars that had been extracted due to periodontal disease were treated by thorough scaling, root planing and root conditioning with tetracycline HCI(100mg/ml, 5 min.) for induction of hypersensitive root. Within middle one third of root mesial surface(30) or distal surface(30) was randomly irradiated by 0.5W-, 0.75W- and 1.0W-power for 2 minutes argon laser(HGM Inc., USA) with or without topical application of 1.23% acidulated phosphate fluoride gel(Pascal, USA). After all teeth were maintained in 2% methylene blue solution for 48 hours and cross-sectioned through irradiated surface of dried roots, methylene blue stained area was compared between irradiated side and nonirradiated side. Following results were obtained : 1. Methylene blue stained area was significantly less in the laser irradiated group than control group(p<0.05). 2. There was no significant difference in methylene blue stained area between 0.5W-power and 0.75W-power group(p>0.1) and between 0.75W-power and 1.0W-power group(p>0.1), but there was significant difference between 0.5W-power and 1.0W-power group(p<0.05). 3. There was no significant difference in methylene blue stained area between two groups with and without topical application of 0.12% acidulated phosphate fluoride gel(p>0.1). The results suggest that argon laser irradiation on hypersensitive root may reduce the hypersensitivity by obstruction of dentinal tubules.

• Journal of Periodontal and Implant Science
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• 제29권4호
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• pp.861-872
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• 1999

Since pathologic changes of exposed root surface inhibit cell attachment and new attachment of connective tissue have been made, many efforts were apply to change the exposed root surface condition. Scaling and root planing can not remove the endotoxin completely and forms the smear layer which prohibits the new attachment of connective tissue. Therefore, many kinds of chemicals were used for controlling the pathologic change of the root surface. The purposes of this study was to compare and observe the changes of the exposed root surface treated by scaling and root planning, Tetracycline HCl and Argon Laser. After the scaling and root planning of ten extracted premolars, the differences & the root surface among groups were observed under SEM. Control group showed smear layer and irregular amorphous surface. The dentinal tubule was not exposed. The debris and scale like texture were also observed. Tetracycline HCl treated group showed relatively smooth surface and the collagen fiber was observed in the dentinal tubule. Argon Laser treated group showed the most effective results under the conditions of 0.8 to 1.0w irradiation for 0.5 to 1.0 sec with pulse wave. The results of this study showed that the root surface change was associated with the intensity and the duration of Argon Laser irradiation. Further investigation for the surface change with the Argon Laser irradiation is recommended for understanding of clinical effect.

• 대한치과기공학회지
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• 제27권1호
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• pp.65-71
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• 2005

Experimental Ti-13%Zr and Ti-13%Zr-5%Cu alloys were made in an argon-arc melting furnace. The grade 2 CP Ti was used to control. The alloys were cast into phosphate bonded $SiO_2$ investment molds using an argon-arc casting machine, and The hardness and microstructures of the castings were investigated in order to reveal their possible use for new dental casting materials and to collect useful data for alloy design. The hardness of the Ti-13%Zr-5%Cu alloy(379Hv) became higher than that of Ti-13%Zr(317Hv) alloy, and the hardness of this alloys became higher than that of CP Ti(247Hv). Increasing in the hardness of the Ti-13%Zr-5%Cu alloy was considered to be solid solution hardening as the Ti-Zr system shows a completely solid solution for both high temperature $\beta$phase and low temperature $\alpha$ phase and also the inclusion of the eutectoid structure($\alpha Ti+Ti_{2}Cu$). No martensitic structures are observed in the specimen made of CP Ti, but Ti-13%Zr and Ti-13%Zr-5%Cu alloys show a kind of martensitic structure. Ti-13%Zr-5%Cu shows the finest microstructure. From these results, it was concluded that new alloys for dental casting materials should be designed as Ti-Zr-Cu based alloys.