• Nuclear Engineering and Technology
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• v.54 no.6
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• pp.1947-1953
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• 2022

As the plasma facing material in the nuclear fusion reactor, tungsten has to bear the irradiation impact of high energy particles. The surface quality of tungsten may affect its irradiation resistance, and even affect the service life of fusion reactor. In this paper, tungsten samples with different surface quality were polished by mechanical processing, subsequently conducted by D₂⁺ implantation and thermal desorption. D₂⁺ implantation was performed at room temperature (RT) with the irradiation dose of 1 × 10²¹ D₂⁺/m² by 5 keV D₂⁺ ions, and thermal desorption spectroscopy measurements were done from RT to 900 K. In addition, He irradiation was also performed by 50 eV He⁺ ions energy with the fluxes of 5.5 × 10²¹ m^-2s^-1 and 1.5 × 10²² m^-2s^-1, respectively. Results reveal that the hydrogen/helium irradiation behavior are both related to surface quality. Samples with high surface quality has superior D₂⁺ retention behavior with less D₂ retained after implantation. However, such samples are more likely to generate fuzzes on the surface after helium irradiation. Different morphologies (smooth, wavy, pyramids) after helium irradiation also demonstrates that the surface morphology is related to tungsten crystallographic orientation.

• The Journal of Korean Academy of Prosthodontics
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• v.34 no.4
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• pp.800-815
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• 1996

Pulsed Nd : YAG laser has been used to treat various soft tissue lesions. However, there have been warnings of using laser to treat peri-implantitis because the laser can alter the surface of implant and can rise its temperature so that it might be harmful to implant itself and its surrounding tissue. However, the study in vivo has not been done yet. The purpose of this study was to evaluate the biocompatibility to the pulsed Nd:YAG lased dental implant. 16 HA coated implants and 16 titanium plasma sprayed implants were used. They were divided 4 groups as unlased control, 0.3 watt, 1.0 watt and 2.0 watt lased groups after lasing. And they were implanted in the peritonial walls of 12 rabbits. The rabbits were sacrificed 6 weeks after implantation and the LM and EM specimems were made. 1. In the unlased implant group, both HA coated and titanium plasma sprayed implants were surrounded by fibroblasts and collagen fibers. No macrophages and inflammatory cells were seen. 2. In HA coated implants 0.3 watt, 1.0 watt lased group had a little inflammation, but in 2.0 watt lased group had scattered macrophages, a significantly larger number of chronic imflammatory cells were seen. 3. In titanium plasma sprayed implant 0.3 watt, 1.0 watt lased group had a little inflammation, but in 2.0 watt group had severe inflammation as in the conditions of HA coated group. 4. The inflammatory reaction of both lased HA coated and titanium plasma sprayed implant groups increased as the increase of the power of the laser.

• Development and Reproduction
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• v.13 no.1
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• pp.1-11
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• 2009

Implantation itself is governed by an array of endocrine, paracrine and autocrine modulators, of embryonic and maternal origin. Window of implantation is the unique temporal and spatial expression of factors allows the embryo to implant via signaling, appositioning, attachment, and invasion in a specific time frame of $2{\sim}4$ days. When the embryo has arrived in the uterine cavity, a preprogrammed sequence of events occurs, which involves the production and secretion of a multitude of biochemical factors such as cytokines, growth factors, and adhesion molecules by the endometrium and the embryo, thus leading to the formation of a receptive endometrium. Cytokines such as LIF, CSF-1, and IL-1 have all been shown to play important roles in the cascade of events that leads to implantation. Integrin, L-selectin ligands, glycodelin, mucin-1, HB-EGF and pinopodes are involved in appositioning and attachment. The embryo also produces cytokines and growth factors (ILs, VEGF) and receptors for endometrial signals such as LIF, CSF-1, IGF and HB-EGF. The immune system and angiogenesis play an important role. The usefulness of these factors to assess endometrial receptivity and to estimate the prognosis for pregnancy in natural and artificial cycles remains to be proven. Integrins, pinopodes, glycodelin and LIF (from biopsies) are promising candidates; from uterine flushings, glycodelin and LIF are also candidates. The ideal serum marker is not available, but VEGF, glycodelin and CSF have some clinical implications. Further evaluation that includes larger groups of infertile women and fertile controls are needed to elucidate whether their presence in plasma, flushing fluid, or endometrial samples can be used as some kind of a screening tool to assess endometrial function and prognosis for pregnancy before and after artificial reproductive therapy. A better understanding of their function in human implantation may lead to therapeutic intervention, thereby improving the success rate in reproduction treatment. New molecular techniques are becoming available for measuring both embryonic and endometrial changes prior to and during implantation. The use of predictive sets of markers may prove to be more reliable than a single marker. Ultimately, the aim is to use these tools to increase implantation in artificial cycles and consequently improve live-birth rates.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• v.29 no.4
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• pp.219-225
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• 2003

Purpose: Platelet Rich Plasma(PRP) application is increasing with sinus inlay bone graft, but there is few research with radiographic ananlysis on effect of PRP in maxillary sinus. The author investigated the amount of bony changes of maxillary sinus for dental implantation among the patients with maxillary inlay graft. Materials and Methods: With 10 patients who were treated with sinus inlay autologous bone grafting combined with PRP technique, and with 5 patients who were treated with sinus inlay grafting only without PRP, the panoramic radiographys which were taken at preoperation, immediate postoperation, 3months postoperation, and 4 months postoperation(a month after dental implantation)periods were analysed. The films had been scanned, and then proceeded throughout image analysis system. The bone density of maxillary grafted sites was compared with adjacent tooth enamel density and remeasured according to density luminosity of each film. The density changes on PRP group and bone graft only group were analysed with non-parameteric statistics method. Results: In PRP combined patients group, bone density on postoperation periods was increased totally. The remarkable enhanced change of bone density was observed on 3 months postoperation period, thereafter the increasing rate was slightly reduced. In only bone graft patients group, bone density on postoperation periods was also increased compared with preoperation period, but the bone density of 4 months postoperation period was decreased compared with 3 months postoperation period. The amount of bone density on PRP group was significantly changed according to periods in contrast to bone graft only group. Conclusion: The bone density on PRP group was remarkably increased at 3 months postoperation compared to bone graft only group and it was seemed to be associated with more new bone formation, less grafted bone resorption at bone grafted sites with PRP.

• Maxillofacial Plastic and Reconstructive Surgery
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• v.20 no.4
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• pp.341-354
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• 1998

GMI (Fibrel${(R)}$) is one of the dermal filling substances which have been successfully used for the treatment of depressed cutaneous scar and wrinkles. It's major components are; Gelatin powder, which provides a framework for the clot to form and remains stable under the scar, and ${\varepsilon}$-aminocaproic acid, which inhibits the production of fibrinolysin, and Plasma, which provides the necessary ingredients for collagen synthesis. GMI has advantages of low immunogenicity and increased longevity. It has been known to induce fibroblast activity and promote new collagen synthesis. We used 34 Sprague-Dawley rats which were bred under the same condition and duration. 18 of experimental animals were undergone cardiac puncture, and their blood were collected, centrifugated, and stored in freezer. Out of 16 animals, control group were injected with 2ml plasma into the subcutaneous tissue of Lt. scapular, while experimental group were implanted of 2 ml GMI into the Rt. same area. Experimental animals were sacrificed at the 3rd day, 5th day, 1st week and 2nd week respectively after implantation of GMI. To observe the histopathologic change of GMI and surrounding tissue reaction of GMI, we had examined with H&E staining, immunohistochemical staining with vimentin, ${\alpha}$-SMA, S-100 under LM and SEM. The obtained results were as follows ; 1. In LM study, the inflammatory cell infiltrations and granulation tissue formation were observed, and muscle tissues were well attached with adipose tissues in the control group. In the experimental group, inflammatory cell infiltrations had been observed by the 2nd week and irregular adipiose tissues and well differentiated mesenchymal tissues were examined. 2. In immunohistochemical study, the experimental group of ${\alpha}$-SMA study, there were a prominent positive response on endothelial development of granulation tissues and mesenchymal tissues compare with the control group. In vimentin study, positive response on mescenchymal fibroblast continued to 2nd week, but negative in the control group. In S-100 study, both groups were positively responded on irregular adipose tissues. 3. In SEM study, collagen fibers were embedded by the plasma by the 5th day in the control group, and in the 3rd day experiment GMI were resorved but communited with collagen fiber till the 1st week. Collagen fibers were infilt-rated into GMI at the 2nd week and the infilltrated GMI were conglomerated with the mature adipose cells and the collagen fibers. From the above results, GMI implantation in the subcutaneous tissue of Sprague-Dawley rat, the mild infiltration of inflammatory cells were showed till 2nd week and the granulation tissues were observed. GMI were nearly resorbed till 2nd week, but well attached with adipose tissue and collagen fibers. The endothelium and fibroblasts were actively proliferated. Adipose tissues and mesenchymal tissue cells were observed. As already expressed, GMI showed resorptive change in course of time without any early immune reaction, and seemed to induce fibroblast activity and promote new collagen synthesis.

• Journal of Periodontal and Implant Science
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• v.23 no.3
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• pp.400-410
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• 1993

Dental implants have been widely used in the treatment of esthetic and functional problems of the mouth due to alveolar bone loss, after tooth extraction. The success of implantation strongly depends on osseointegration. For osseointegration, implant material, methodology, and design have been investigated. For materials, two popular materials at present are titanium and hydroxyapatite. For methods, immediate implantation is being used recently. The purpose of this study is to evaluate osseointegration between the unthreaded cylindrical TPS implant and the HA-coated implant by a histomorphometric analysis. For this analysis, experimental periodontits was induced on the 3, 4 premolars of adult dogs by the ligation of orthodontic threads. Thereafter, each tooth was extracted. TPS. Implants and HA-coated implants were immediately inserted in the extraction socket. In control group, TPS implants were immediately inserted, and In experimental group, HA implants were immediately inserted. The dogs were sacrificed after 12 weeks, then the specimens were prepared for LM and histomorphometric analysis. The conclusion of this study is as follows l. In both control and experimental group, no inflammatory cells were observed. 2. The results of the histomorphometric analysis showed that the total osseointegration was 48.5% in control group, and 68.8% in expermental group. The experimental group was higher than the control group, and the difference was not statistically significant (p<0.05). 3. The results of the histomorphometric analysis showed that the osseointegration in the hole was 40.6% in control group, and 70.2% in experimental group. The experimental group was higher than the control group, and the difference was statistically significant (p<0.05). In both control and experinental group, no inflammatory cells were observed. 4. The results of the histomorphometric analysis showed that the osseointegration in the lower part was 52.1% in control group, and 73.3% in experimental group. The experimental group was higher than the control group, and the difference was statistically significant (p<0.05). 5. In experimental group, the bone to HA interface seemed to be mixed of bone and HA. We could not distinguish HA from the bone. The HA coating was detached from the titanium surface.

• Proceedings of the KIEE Conference
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• 2005.11a
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• pp.197-200
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• 2005

As Plasma Immersion ion Implantation (PIII) using a conducting grid is very useful to reduce the effect of capacitance and charging in surface modification. If the bias voltage applied to the conducting grid is in the range of hundreds of volts, the effects of surface charge and space charge substantially affect the incident ion energy and ion current to the surface. In this paper, through an 1d and a 2d PIC simulation the time varying formation of the space charge and surface charge is analyzed. Experiment with the optimally designed grid on the basis of the simulation results is conducted, and the results of both cases with grid and without grid are compared. In our work with Poly Urethane(PU), the improvement of adhesion is yielded by increasing surface roughness and decreasing Si component of PU.

• Korean Journal of Materials Research
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• v.1 no.1
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• pp.23-28
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• 1991

The resistivity of polycrystalline silicon film deposited by low pressure chemical vapor deposition and doped by arsenic Implantation has been investigated as a function of dopant concentration and testing temperature ranging from $25^{\circ}C$ to $105^{\circ}C$ . The resistivity vs. doping concentration curve had a peak point with highest activation energy with respect to the dependence of the resistivity on temperature. We showed that $O_2$ plasma anneal followed by heat-treatment in $N_2$ ambient was able to recover the resistivity degraded by the plasma deposited passivation layers.

• Korean Journal of Materials Research
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• v.4 no.2
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• pp.152-158
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• 1994

Diamondlike carbon thin film have been fabricated using methane as a reactive gas by plasma enhanced chemical vapor deposition. Effects of hydrogen gas on the optical properties of the thin film has been investigated. When the hydrogen was used as a secondary gas, the role of hydrogen changed with deposition power unlike inert gases such as Ar and He. From the changes of optical band gap and FT-IR analysis, it was predicted that the chemical etching, sputtering of C-H bond by hydrogen and the implantation of hydrogen into the thin film could occur. The validity of the possibilities was confirmed by examining the effect of secondary gases such as Ar and He.

• Journal of Korean Society of Environmental Engineers
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• v.35 no.5
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• pp.356-362
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• 2013

An attempt has been made to optimize elongated rotating arc plasma $NH_3$ scrubber. Among diverse semiconductor processes, diffusion and implantation process inevitably produce $NH_3$ as byproduct and efficient dry process for the decomposition of $NH_3$ is required. Plasma process does not produce NOx that is commonly produced in combustion process and there is no problem of deactivation, usually experienced in catalyst process. However, plasma process uses electrical energy and needs to be optimized to achieve feasibility of application. In this work, mode control of rotating arc is presented as tentative solution for the possible optimization of the process. Based on existing rotating arc, scale-up and following mode mapping was tried. Proposed reactor design was evaluated in the $NH_3$ decomposition process and revealed that optimization scheme is at hand. In the experiment of full scale scrubber including heat exchanger, the process gave more stable and efficient process of $NH_3$ decomposition.