• Journal of Korean Academy of Oral and Maxillofacial Radiology
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• v.19 no.1
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• pp.69-87
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• 1989

It is well known that the glucocorticoid induces osteoporosis by suppression of the osteoblast, but its effect on the osteoclast hRS some controversy whether it activates or suppresses the osteoclast. If the calcitonin, which is known to suppress the osteoclast, prevents the osteoporosis by glucocorticoid, then the suppression of the osteoclast by the glucocorticoid is not so significant. And if the calcitonin increases the osteoblastic activity, Tc-99m MDP uptake will be increased in spite of the glucocorticoid effect on the osteoblast. The immobilization operation was performed to the right leg of male Wistar rats weighing about 200gm. each. For 16 weeks after operation, rats were injected glucocorticoid alone or glucocorticoid anci calcitonin. The bone density was measured by means of photodensitometry under reference aluminum step wedge and Tc-99m MDP uptake was available to the index of the osteoblastic activity. 1. The bone density of femora! head was markedly reduced than that of femoral shaft following ration of cancellous and cortical components in both site. 2. Glucocorticoid caused decrease in bone density of spine and femur, md there is significantly increase of it when medication of glucocorticoid and calcitonin injection simultaneously than that of glucocorticoid. 3. Tc-99m MDP uptake was revealed significant reduction in medication of glucocorticoid but increase in gi;.:cocorticoid and calcitonin injection simultaneously in later experimental period. 4. There wail, a slight reduction in plasma osteocalcin in medication of glucocorticoid through experimental periods and an increase in its value in case of giving glucocorticoid and calcitonin simultaneously in later experimental period. From these results, we suggest that osteoporosis by immobilization is more pronounced by glucocorticoid hormone and osteoporosis induced by immobilization and glucocorticoid use is prevented by calcitonin administration with increasing osteoblastic activity.

• Restorative Dentistry and Endodontics
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• v.45 no.1
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• pp.6.1-6.8
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• 2020

Objectives: This study investigated the effects of a hydrofluoric acid (HA; solution of hydrogen fluoride [HF] in water)-based smart etching (SE) solution at an elevated temperature on yttria-stabilized tetragonal zirconia polycrystal (Y-TZP) ceramics in terms of bond strength and morphological changes. Materials and Methods: Eighty sintered Y-TZP specimens were prepared for shear bond strength (SBS) testing. The bonding surface of the Y-TZP specimens was treated with 37% phosphoric acid etching at 20℃-25℃, 4% HA etching at 20℃-25℃, or HA-based SE at 70℃-80℃. In all groups, zirconia primers were applied to the bonding surface of Y-TZP. For each group, 2 types of resin cement (with or without methacryloyloxydecyl dihydrogen phosphate [MDP]) were used. SBS testing was performed. Topographic changes of the etched Y-TZP surface were analyzed using scanning electron microscopy and atomic force microscopy. The results were analyzed and compared using 2-way analysis of variance. Results: Regardless of the type of resin cement, the highest bond strength was measured in the SE group, with significant differences compared to the other groups (p < 0.05). In all groups, MDP-containing resin cement yielded significantly higher bond strength values than MDP-free resin cement (p < 0.05). It was also shown that the Y-TZP surface was etched by the SE solution, causing a large change in the surface topography. Conclusions: Bond strength significantly improved when a heated HA-based SE solution was applied to the Y-TZP surface, and the etched Y-TZP surface was more irregular and had higher surface roughness.

• The Korean Journal of Nuclear Medicine
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• v.35 no.4
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• pp.291-292
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• 2001

We report a case of malignant pericardial effusion originated from adenocarcinoma of the lung incidentally diagnosed by bone scintigraphy, prior to echocardiographic detection. A 76 year-old man with adenocarcinoma of the lung underwent Tc-99m MDP bone scintigraphy to evaluate skeletal metastasis. Anterior images of the chest of the bone scintigraphy unexpectedly showed diffuse increased activity in the region of the heart surrounded by an oval-shaped band of increased activity corresponding to the periphery of the cardiac silhouette (Fig. 1). There was no evidence of bony metastasis. Pericardial effusion was confirmed by echocardiography (Fig. 2) and malignant cells were revealed by subsequent microscopic examination of the pericardial fluid. Bone scintigraphy using Tc-99m phosphate compounds is commonly used to detect bony metastasis in cancer patients. Tc-99m phosphate compounds occasionally accumulate in extra-osseous sites, including $pleural^{1,2)},\;pericardial^{3,4)},\;and\;ascitic\;fluids^{5,6)}$. It has been reported that their accumulation in serous effusions should strongly suggest $malignancy^{1-6)}$. The exact mechanism for accumulation of Tc-99m phosphate compounds in serous effusions is unclear. Several investigators have proposed that the radiopharmaceuticals exuded directly from peripheral vessels to the serous cavity due to increased vascularity and vascular permeability, and bleeding by disruption of blood vessels due to cancerous $infiltration^{5,6)}$.

• The Korean Journal of Nuclear Medicine
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• v.27 no.1
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• pp.98-103
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• 1993

The present study was purposed to evaluate the incidence and the characteristics of metastatic "cold" lesions in $^{99m}Tc$-MDP bone scans of adult patients with solid malignancies. There were 29 cold lesions in 24 patients. The incidence of cold lesions was about 1% of total cases of bone scans for the patients with malignancy, or 2.5% of cases with bone metastases. Th primary sites of malignancies were lung (four cases), uterine cervix (three cases), kidney, nasopharynx, thyroid, urinary bladder, prostate, lymphoma (two cases each other), liver, breast and others (one case each other). But the relative incidence of cold lesion in lung cancer and breast cancer was low. The most frequent site of cold lesion was spine, and pelvis, skull and rib were followed. The incidence of cold lesion was related to the regional incidence of bone metastases. The size of the cold lesions was greater than that of the hot. There were six cases of single cold lesion without any other abnormalities and two cases of cold lesion which were initially hot. So it should be considered that bone metastases might be presented as cold lesions in bone scan.

• The Journal of Advanced Prosthodontics
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• v.12 no.4
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• pp.197-203
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• 2020

PURPOSE. The aim of this study was to evaluate the effect of multiple firings on the bond strength between yttriatetragonal zirconia polycrystals (Y-TZP) and 2 types of resin cements. MATERIALS AND METHODS. Sixty 3Y-TZP specimens (LAVA Frame Multi) were divided into 3 groups depending on the following firing procedures: (1) 2-firing cycles, (2) 5-firing cycles, (3) 10-firing cycles. Two samples from each group were investigated by using SEM to determine the morphological changes. All specimens were treated with 125 ㎛ airborne-particle abrasion and the surface roughness of each specimen was measured. The specimens from each firing group were then further divided into 2 subgroups (n = 9) to apply 2 types of resin cement (MDP-free resin cement: RelyX Unicem-RU, and MDP containing resin cement: Panavia F 2.0-PA). The shear bond strength (SBS) test was performed and failure types of all the debonded specimens were classified by using a stereomicroscope as adhesive, cohesive, and mixed. The statistical analysis of surface roughness and SBS data were performed by using 1-way ANOVA and 2-way ANOVA followed by Tukey-HSD tests (α=.05). Failure modes were calculated as a percentage for each group. RESULTS. The bond strength of RU and PA to the specimens obtained with 2 firings were not statistically different from each other (P=.1). However, the SBS values of PA were found to be significantly higher than RU for the specimens obtained with 5 and 10 firing cycles (P=.001 and P=.02, respectively). Surface roughness analysis revealed no statistical difference between groups (P=.2). The SEM analysis of samples fired 5- and 10- times showed irregularities and boundary loss in zirconia grains, and empty spaces between zirconia grains. CONCLUSION. The bond strength of PA cement was higher than that of RU to the zirconia subjected to repeated firings (5 and 10 firing cycles). When zirconia is subjected to multiple firings, using MDP-containing resin cement can be recommended.

• The Journal of Korean Academy of Prosthodontics
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• v.38 no.4
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• pp.510-525
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• 2000

The effects of pretreatment of Co-Cr alloy, including two adhesive primers that contain either MDP or MAC-10, and silicoating on the bond The result sobtained as follows; o Strength of 4-META/MMA-TBB resin were investigated using FT-IR, SEM, and EDAX. o In the SEM observation of surface morphologies, the sandblasted specimen exibited a very rough surface, whereas the surfaces of the two groups primed with either MDP or MAC-10 were covered with a layer of primer, and the surface morphology of the silicoated specimen remained almost the same after sandblasting. o Before the thermocycling tests, the group treated with MDP demonstrated the highest mean tensile bond strength and the sandblasted group showed the lowest bond strength. o After 20,000 thermocyling, the mean tensile bond strength of the sandblasted group exhibited a 50% reduction in bond strength, while the others showed a $20\sim30%$ reduction. o Observation of the metal-resin interface revealed that in all groups the resin permeated the rough surface formed by sandblasting thereby producing a mechanical bond between the metal and the resin. It was also found that thermocycling resulted in a gap formation at the metal-resin interface of the specimens, and the sandblasted group exhibited a larger gap width than the other groups. o In fracture mode, all specimens indicated a cohesive fracture within the resin before thermocycling. However, thermocyling produced adhesive failure at the edge of the resin-metal interface in most specimens. The sandblasted group, which exhibited the lowest bond strength after thormocycling, also demonstrated the largest area of adhesive failure.

• The Korean Journal of Nuclear Medicine
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• v.24 no.1
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• pp.119-123
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• 1990

Unexpected renal abnormality can be detected on bone scan using Tc-99m-MDP. The purpose of the study is to evaluate the diagnostic significance of diffusely increased bliateral renal uptake on bone scarf. 1,500 boor scan were reviewed and 43 scans which showed diffusely increased bliateral renal uptake were selected for analysis. Laboratory findings for renal and liver function tests including routine urinalysis were reviewed in 43 patients. 26 of 43 case showed abnormality in urinalysis and renal function stud 20 of 43 cases showed abnormal liver function study and 3 of these cases were diagnosed as hepatorenal syndrome later. 13 of those 20 cases had liver cirrhosis with or without hepatoma. 12 of 43 cases showed abnormality both in renal and liver function studies. 2 of 43 cases showed diffusely increased bilateral renal uptake after chemotherapy for cancer but not on previous scans before chemotherapy. 2 of 43 cases showed hypercalcemia and 8 of 43 cases had multifocal bone uptake due to metastasis or benign bone lesion. but the latter showed no hypercalcemia at all. There was no significant correlatrion between increased renal uptake and MDP uptake in soft tissue other than kidneys. This study raised the possibility that the impaired liver and/or renal function may result in diffuse increase of bliateral renal uptake of MDP of unknown mechaninsm. It seems to need further study on this correlation.

• The Korean Journal of Nuclear Medicine
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• v.24 no.1
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• pp.133-137
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• 1990

The general use of a number of $^{99m}Tc-labelled$ compounds makes the need for good routine quality control procedures, especially the labelling efficiency measurements. The purpose of these study were to measure the labelling efficiency of $^{99m}Tc-labelled$ MDP, DTPA, Tin colloid, and Antimony sulfide colloid using miniaturized paper and instant thin layer chromatography. The chromatographic systems include whatman 3 MM paper and acetone, Gelman ITLC-SG and 0.9% sodium chloride. The chromatographic strips are miniaturized $(1\times10\;cm)$, marked and numbered. Labelling efficiencies of $^{99m}Tc-labelled$ DTPA and Tin colloid were above 98.0%. $^{99m}Tc-labelled$ Antimony sulfide colloid was 90.0%. And labelling efficiency of $^{99m}Tc-labelled$ MDP was 89.0% Coefficient variance of $^{99m}Tc-labelled$ MDP, DTPA, Tin colloid, and Antimony sulfide colloid were 5.14%, 2.06%, 1.82% and 4.90%, respectively. We found that this miniaturized chromatographic quality control was simple and reliable.

• Journal of the Korea Society for Simulation
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• v.27 no.1
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• pp.1-13
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• 2018

Earthwork planning is one of the critical issues in a construction process management. For the construction process management, there are some different approaches such as optimizing construction with either mathematical methodologies or heuristics with simulations. This paper propose a simulated earthwork scenario and an optimal path for the simulation using a reinforcement learning. For reinforcement learning, we use two different Markov decision process, or MDP, formulations with interacting excavator agent and truck agent, sequenced learning, and independent learning. The simulation result shows that two different formulations can reach the optimal planning for a simulated earthwork scenario. This planning could be a basis for an automatic construction management.

• Journal of the Society of Naval Architects of Korea
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• v.56 no.1
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• pp.58-65
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• 2019

The stability, reliability and efficiency of a smart ship are important issues as the interest in an autonomous ship has recently been high. An automatic collision avoidance system is an essential function of an autonomous ship. This system detects the possibility of collision and automatically takes avoidance actions in consideration of economy and safety. In order to construct an automatic collision avoidance system using reinforcement learning, in this work, the sequential decision problem of ship collision is mathematically formulated through a Markov Decision Process (MDP). A reinforcement learning environment is constructed based on the ship maneuvering equations, and then the three key components (state, action, and reward) of MDP are defined. The state uses parameters of the relationship between own-ship and target-ship, the action is the vertical distance away from the target course, and the reward is defined as a function considering safety and economics. In order to solve the sequential decision problem, the Deep Deterministic Policy Gradient (DDPG) algorithm which can express continuous action space and search an optimal action policy is utilized. The collision avoidance system is then tested assuming the $90^{\circ}$intersection encounter situation and yields a satisfactory result.