• Journal of The Korean Association For Science Education
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• v.34 no.2
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• pp.165-173
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• 2014

The purpose of this study is to investigate the stress factors experienced by science teachers and stress related to science teaching. To do these, I have developed the Science Teacher Stress Inventory, which consisted of 50 stress factors with subcategories such as student characteristics, teacher characteristics, school environment, administrative procedures, and conditions of service. 104 science teachers have participated in this questionnaire survey. Additionally, I got 109 stress cases related to science teaching from surveys of 25 science teachers. Results are as follows: first, stress from students characteristic and administrative procedures are perceived as having more stress factors than teacher characteristics, school environment, and conditions of service. Second, stress in affective domains such as students' low motivation in science and insincere class attitude is perceived as having more stress factors than stress in cognitive domain. Third, female science teachers are significantly more stressed than male science teachers. Fourth, students' low motivation and low understanding in science learning are the most stressful factors in stress related to science teaching. Fifth, science teachers feel more stress in evaluation such as experiment test and joint-set exam questions.

• International Journal of Oral Biology
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• v.38 no.4
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• pp.135-140
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• 2013

The present study investigated the effects of QX-314 on inflammatory pain of the temporomandibular joint (TMJ). Experiments were carried out on male Sprague-Dawley rats weighing 220-280 g. Under anesthesia, the TMJ of each animal was injected with $50{\mu}L$ of formalin (5%). The number of noxious behavioral responses, including rubbing or scratching of the facial region including the TMJ area, was recorded over 9 sequential 5 min intervals for each animal. Although 2.5% QX-314 did not affect formalin-induced nociceptive behavior, administration of 5% QX-314 with formalin significantly decreased the number of scratches produced by the formalin injection. Co-administration of capsaicin, a TRPV1 agonist, with 2.5% QX-314 produced significant anti-nociceptive effects whereas 2.5% QX-314 alone did not. However, the co-administration of capsaicin did not enhance the anti-nociceptive effects in the 5% QX-314-treated rats. Moreover, the co-administration of capsazepine, a TRPV1 antagonist, did not attenuate anti-nociceptive effects in the 5% QX-314-treated rats. These findings suggest that TRPV1 is effective in the transport of low but not high doses of QX-314. Moreover, a high dose of QX-314, which is not mediated by peripheral TRPV1 activity, may be viable therapeutic strategy for inflammatory pain in the TMJ.

• Journal of Haehwa Medicine
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• v.24 no.2
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• pp.35-57
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• 2016

Objectives : The purpose of this study is to prove the effect and mechanism of Gamikyejakjimogawusul-tang(GKHA) herbal acupuncture on induced rheumatoid arthritis model of DBA/1 mice. Methods : We check effect of GKHA extract on the AST, ALT, Creatinine, BUN of serum and cell viability of GK extract in RAW 264.7 cells to test the stability of this study. In vitro, we measure total phenol contents, total flavonoid contents, DPPH free radical scavenging activity, ABTS cation radical scavenging activity of Gamikyejakjimogawusul-tang, effect of GK extract on ROS(Reactive Ooxygen Species) production to estimate a anti-oxidant capacity, and we also measure effect of GK extract on NO (Nitric Oxid), IL-$1{\beta}$, IL-6, IL-17, IL-21, TNF-${\alpha}$, MCP-1, GM-CSF production in RAW 264.7 cells to estimate a anti-inflammatory efficacy. In vivo, we compare a rheumatoid arthritis manifestation between control and experimental group and estimate a AI. Then we check effect of GKHA on the level of WBC, neutrophil, lympocyte, monocyte in the blood to see the effect of immune cells in blood. In addition we measure effect of GKHA on the level of hs-CRP, IgM, IgG, IL-$1{\beta}$, IL-6, IL-17, IL-21, TNF-${\alpha}$, MCP-1, GM-CSF in serum. We observe effects of GKHA on imaging of cartilage degeneration using micro CT-arthrography in paw hind. And we calculate effects of GKHA that reduced BV ratio, BS/BV ratio using 3D Micro-CT. Lastly we observe effects of GKHA histopathologic examination analysis. Results : 1. The toxicity on liver and kidney was disregardable and the cytotoxicity against RAW 264.7 cells was also disregardable. 1. Total phenol contents and total flavonoid contents in GK extract were in high level. 2. DPPH free radical scavenging activity and ABTS cation radical scavenging activity were increased according to concentration of GK extract 3. ROS production was significantly decreased in GK extract (at 10, $100{\mu}g/ml$). 4. NO, IL-6, TNF-${\alpha}$, MCP-1 production were significantly decreased in GK extract(at 10, $100{\mu}g/ml$). IL-17, GM-CSF production were significantly decreased in GK extract(at 1, 10, $100{\mu}g/ml$). IL-$1{\beta}$, IL-21 production were also decreased but there was no statistical significance. 5. 25x observation after H&E and M-T staining, infiltration of immune cells and subsidence of the cartilage and damage to the synovial cells were decreased. Conclusions : This study showed that GKHA extract had anti-oxidant capacity, anti-inflammatory efficacy. GKHA extract also had inhibiting effect on the process of rheumatoid arthritis and can protect joint and cartilage. So we expect that GKHA extract can be a meaningful treatment to rheumatoid arthritis patients.

• Journal of Aerospace System Engineering
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• v.12 no.3
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• pp.18-25
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• 2018

This research aims to establish the finite-element modeling techniques for computational modal analyses of liquid propellants and flange joints of launch-vehicle structures. MSC.NASTRAN is used for the present computational modal analyses of the liquid-propellant tank and the small-scaled first-stage model. By means of the correlation between the measured and computed natural frequencies, the finite modeling techniques for liquid propellants and flange joints of launch-vehicle structures are established appropriately. This modal analysis using the virtual-mass method predicts well the bell mode of the liquid-propellant tank containing liquid. In addition, the present computation using RBE2 elements for modeling of flange joints predicts the first and second bending-mode frequencies within a relative error of 10%, which is better than the measured frequencies obtained from the modal test, for the small-scaled first-stage model containing liquid.

• The Journal of Korean Academy of Prosthodontics
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• v.55 no.3
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• pp.251-257
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• 2017

Purpose: The purpose of this study was to evaluate whether the internal abutment length affected screw stability in an internal connection implant. Materials and methods: Twenty long internal connection implants (Replus system, $4.7{\times}11.5mm$) were selected for this investigation. Abutments were assigned to four groups depending on the length of the internal connection (abutments with internal lengths of 1, 2, 3, and 4 mm, respectively). Each implant fixture specimen was embedded in resin medium and connected to an abutment with an abutment screw. A load of 100 N, applied at an angle of $30^{\circ}$ to the long axis of the implant, was repeated for $1.0{\times}10^6$ cycles. Reverse torque values (RTV) were recorded before and after loading, and the change in RTV was calculated. Data were analyzed with the Kruskal-Wallis test. Results: The change in RTV was not significantly different among the groups (P>.05). Screw loosening and fractures were not observed in any groups, and joint stability was maintained. Conclusion: The internal length of the abutment may not significantly affect the degree of screw loosening.

• International Journal of Highway Engineering
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• v.11 no.2
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• pp.121-132
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• 2009

Thin bonded continuously reinforced concrete overlay(CRCO) was constructed on He existing jointed plain concrete pavement(HCP) surface at Seo-Hae-Ahn express highway in South Korea in order to evaluate its applicability and performance. Two sections of road were considered for this evaluation. In the first section, the concrete overlayer was placed and cut down to the existing layer to form transverse joints while CRCO was constructed on top of the existing layer in the second section. Early strength concrete(Type III) was utilized for both overlay sections. The depth of milling and the thickness of overlaid layer were 5 cm and 10 cm, respectively. Several vibrating wire gauges(VWG) were installed to evaluate the performance of CRCO with respect to curling, delamination, and crack propagation. As a result of the strength test, it was found that strength of the material reaches the design criteria within 1-3 days. Analysis with vibrating wire gauge(VWG) showed CRCO effectively restricts joint movement. High adhesive strength also was observed from the material regardless of length of aging. Meanwhile, transverse cracks were observed on the middle of the section where JPCP overlay was applied whereas arbitrarily cracks in transverse direction were observed on the section where CRCP was applied.

• Journal of the Microelectronics and Packaging Society
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• v.7 no.4
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• pp.7-15
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• 2000

The purpose of this work is to evaluate the solderahility and characteristics of solder joints. Bridge defect of solder joint was examined in natural atmosphere and $N_2$ condition. Consequently, wettability was excellent for each of Sn-Pb plated Cu specimen, Sn plated Cu specimen, and Cu polished in $N_2$ condition. The wetting time in $N_2$ condition was shorter than that of natural atmosphere condition, showing the decreasing values of about 0.2~0.45 seconds. The max. wetting force under the $N_2$ condition was more increasing that of natural atmosphere condition, showing the increasing values of about 1.8~2.8 N. With the result of wetting balance test, the wetting time ($t_2$) and wetting farce according to increasing amount of $N_2$ from 10 1/min to 30 1/min, the wetting time ($t_2$) was reduced about 0.25 second and wetting force was increased about 2.3 N. In non-cleaning flux, when $N_2$ gas is applied, it is compensated to decrease of wettability. In the case of using the $N_2$ gas, the wettability was improved. The reason for improving wettability is due to preventing the formation of dross. The generation rate of bridge in $N_2$ condition decreased than that of natural atmosphere, and when the specimen had a fine pitch, the rate of bridge defects was considerably decreased in $N_2$ condition, showing the decreasing rate of 25~75%.

• Magazine of the Korea Concrete Institute
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• v.11 no.2
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• pp.147-156
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• 1999

An investigation was conducted into the flexural behavior of earthquake damaged reinforced concrete columns repaired with carbon fiber sheets. Six column specimens were tested to failure under reversed cyclic loading. Two columns were specimens for control with no sheets and tested. These columns were repaired with carbon fiber sheets and retested to evaluate the effect of the confinement of the carbon fiber on the damaged column. Another two columns were repaired and tested with no pre-cyclic loading. The test specimens were designed to model single bent under a constant axial force with reversed cyclic lateral loading. Carbon fiber sheets were used to repair damaged concrete columns in the critically stressed areas near the column footing joint and the physical, mechanical properties of carbon fiber sheets are described. The performance of repaired columns in terms of their hysteretic response is evaluated and compared to those of the original columns. The results indicate that the repaire technique with carbon fiber sheets is highly effective. Both flexural strength and displacement ductility of repaired columns were higher than those of the original columns.

• Journal of the Korea Concrete Institute
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• v.13 no.1
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• pp.1-8
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• 2001

Recently, prestressed concrete(PSC) bridge structures with many repetitive spans have been widely constructed using the segmental construction method in many countries. In these segmentally constructed PSC bridges, there exist many construction joints which is required coupling of tendons or overlapping of tendons to introduce continuous prestress through several spans of bridges. The purpose of this paper is to investigate in detail the complicated stress distributions around the tendon coupled joints in prestressed concrete girders. To this end, a comprehensive experimental program has been set up and a series of specimens have been tested to identify the effects of tendon coupling. The present study indicates that the longitudinal and transverse stress distributions of PSC girders with tendon couplers are quite different from those of PSC girders without tendon couplers. It is seen that the longitudinal compressive stresses introduced by prestressing are greatly reduced around coupled joints according to tendon coupling ratios. The large reduction of compressive stresses around the coupled joints may cause deleterious cracking problems in PSC girder bridges due to tensile stresses arising from live loads, shrinkage and temperature effects. The analysis results by finite element method correlate very well with test results observed complex strain distributions of tendon coupled members. It is expected that the results of this paper will provide a good basis for realistic design guideline around tendon coupled joints in PSC girder bridges.

• Journal of the Korea Concrete Institute
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• v.13 no.6
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• pp.593-601
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• 2001

In RC structure, sufficient anchorage of reinforcement is necessary for the member to produce the full strength. Generally, conventional standard hook is used for the reinforcement's anchorage. However, the use of standard hook results in steel congestion, making fabrication and construction difficult. Mechanical anchor offers a potential solution to these problems and may also ease fabrication, construction and concrete placement. In this paper, the required characteristics and the design considerations of mechanical anchor were studied. Also, the mechanical anchor was designed according to the requirements. To investigate the pull-out behavior and properness of mechanical anchorage, pull-out tests were performed. The parameters of tests were embedment length, diameter of reinforcement, concrete compressive strength, and spacing of reinforcements. The strengths of mechanical anchor were consistent with the predictions by CCD method. The slip between mechanical anchor and concrete could be controlled under 0.2mm. Therefore, the mechanical anchor with adequate embedment could be used for reinforcement's anchorage. However, it was observed that the strength of mechanical anchors with short spacing of reinforcements was greatly reduced. To apply the mechanical anchor in practice (e.g. anchorage of the beams reinforcements in beam-column joint), other effects that affect the mechanical anchor mechanism, such as confinement effect of adjacent member from frame action or effects of shear reinforcement, should be considered.