• Journal of the Korea Concrete Institute
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• v.25 no.1
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• pp.63-72
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• 2013

HTB (hybrid truss bridge) steel truss webs instead of concrete webs in prestressed box girder bridges has been widely used in, because of its structural benefit such as relatively less self-weight and good aesthetics due to open web structure. Since the core technology of this bridge is the connection system between concrete slabs and steel truss members, several connection systems were proposed and experimentally evaluated. Also, the selected joint system was applied to the real bride design and construction. The researches were performed on the connection system, since it can affect the global behavior of this bridge such as flexural and fatigue behaviors as well as the local behavior around the connection region. The evaluation study showned that HTB applied to a curved bridge or a eccentric loading bridge, characteristic has a weak torsional capacity compared to an ordinary PSC box girder bridges due to the open structure of HTB. In this study, three box shaped hybrid truss specimens were made and the torsional test and evaluation for them were performed in order to find out the torsional behavior of HTB according to the connection system.

• Journal of Dental Rehabilitation and Applied Science
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• v.19 no.4
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• pp.269-279
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• 2003

This study investigated the mechanical properties of precious metal-ceramic alloy joined by the laser-welding and the soldering compared with the parent metal. Twenty-four tensile specimens were cast in precious metal-ceramic alloy and divided into three groups of eight. All specimens in the control group(group 1) were left in the as-cast condition. Group 2 and 3 were the test specimens, which were sectioned at the center. Eight of sectioned specimens were joined by soldering with a propane-oxygen torch, and the remaining specimens were joined by laser-welding. After joining, each joint diameter was measured, and then tested to tensile failure on an Instron machine. Failure loads were recorded, and then fracture stress(ultimate tensile strength), 0.2% yield strength and % elongation calculated. These data for three groups were subjected to a one-way analysis of variance(ANOVA). Neuman-Keuls post hoc test was then used to determine any significant differences between groups. The fracture locations, fracture surfaces were examined by SEM(scanning electron microscope). The results were as follows: 1) The tensile strength and 0.2% yield strength of the soldered group($280.28{\pm}49.35MPa$, $160.24{\pm}26.67MPa$) were significantly less than both the as-cast group($410.99{\pm}13.07MPa$, $217.82{\pm}17.99MPa$) and the laser-welded group($383.56{\pm}59.08MPa$, $217.18{\pm}12.96MPa$). 2) The tensile strength and 0.2% yield strength of the laser-welded group were about each 98%, 99.7% of the as-cast group. There were no statistically significant differences in these two groups(p<0.05). 3) The percentage elongations of the soldered group($3.94{\pm}2.32%$) and the laser-welded group($5.06{\pm}1.08%$) were significantly less than the as-cast group($14.25{\pm}4.05%$) (p<0.05). 4) The fracture of the soldered specimens occurred in the solder material and many porosities were showed at the fracture site. 5) The fracture of the laser-welded specimens occurred also in the welding area, and lack of fusion and a large void was observed at the center of the fracture surface. However, the laser-welded specimens showed a ductile failure mode like the as- cast specimens. The results of this study indicated that the tensile strengths of the laser-welded joints were comparable to those of the as-cast joints and superior to those of the soldered joints.

• Composites Research
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• v.29 no.2
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• pp.45-52
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• 2016

An understanding of the failure mechanisms of the adhesive layer is decisive in interpreting the performance of a particular adhesive joint because the delamination is one of the most common failure modes of the laminated composites such as the fiber metal laminates. The interface between different materials, which is the case between the metal and the composite layers in this study, can be loaded through a combination of fracture modes. All loads can be decomposed into peel stresses, perpendicular to the interface, and two in-plane shear stresses, leading to three basic fracture mode I, II and III. To determine the load causing the delamination growth, the energy release rate should be identified in corresponding criterion involving the critical energy release rate ($G_C$) of the material. The critical energy release rate based on these three modes will be $G_{IC}$, $G_{IIC}$ and $G_{IIIC}$. In this study, to evaluate the fracture behaviors in the fracture mode I and II of the adhesive layer in fiber metal laminates, the double cantilever beam and the end-notched flexure tests were performed using the reference adhesive joints. Furthermore, it is confirmed that the experimental results of the adhesive fracture toughness can be applied by the comparison with the finite element analysis using cohesive zone model.

• Investigative Magnetic Resonance Imaging
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• v.18 no.2
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• pp.157-166
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• 2014

Purpose : The purpose of this study is to determine whether adding an angled oblique sagittal plane to the routine shoulder MRI improves the diagnostic performance in the evaluation of supraspinatus tendon tears with arthroscopic correlation. Materials and Methods: The study included 121 patients who had a shoulder MRI followed by arthroscopy. Two radiologists separately evaluated the supraspinatus tendon for tears on shoulder MRI either with or without the angled oblique sagittal images. Arthroscopy was used as the reference standard. The sensitivity and specificity for diagnosing supraspinatus tendon tears were calculated and compared by using McNemar test. Interobserver and intertechnique variability in the interpretation of supraspinatus tendon tears were calculated as a kappa value. Results: Adding the angled oblique sagittal images to the standard shoulder MRI showed improvement in the sensitivity for diagnosing full-thickness supraspinatus tendon tears and also in the sensitivity, specificity and accuracy for the detection of partial-thickness tears. However, there was no statistically significant difference in all of them between with and without the angled set. Interobserver agreement was substantial to almost perfect and intertechnique agreement was moderate. Conclusion: Adding an angled oblique sagittal plane image to the routine shoulder MRI showed no significantly different diagnostic performance in detecting the partial- and full-thickness supraspinatus tendon tears, compared to MRI without angled oblique sagittal plane.

• Journal of the Korean Academy of Child and Adolescent Psychiatry
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• v.10 no.1
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• pp.76-90
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• 1999

This study was performed 1) to compare the nature of the synchronized behaviors in mother-child plays between autistic and normal groups quantitatively and qualitatively and 2) to identify the behavioral data to improve synchrony. The subjects were consisted of 20 mother-child pairs, 10 for each autistic group(AG) and normal group(NG). The developmental age of two groups was under 24 months old and equally matched. Data were collected by video-taped mother-child free play and analyzed with Wilcoxon Rank Sign(Sum) Test, Spearman Correlation Coefficient, Scheffe's Test, and Content Analysis. The score on synchronized behaviors of AG was significantly lower than that of NG(p<.05). As time progressed, the difference was much higher between the 2 groups. And the structure of motherchild plays in AG was poor and most of the interactions were discontinued as 1 or 2 episodes. On the other hand, mother-child plays in NG were enriched and became somewhat like game or play. The score of mother's growth-fostering nurturing behaviors showed positive relation to synchrony and much highly related to the group of 16 months-old or above. Mother's laughing and patting responses and pausing to get the child's initiative were especially related highly to synchronized behaviors. In conclusion, these mother's growth-fostering nurturing behaviors should be stressed at the mother-child interactions and also well structured therapeutic play with considering in children's developmental level should be given.

• Korean Journal of Adult Nursing
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• v.12 no.2
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• pp.296-310
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• 2000

During the past 10 years, concern for community people's health has increased together with the changes. Public health policies and studies for community people's health, however, have influenced those in childmaternal health care to want more general coverage and studies of health and wellness. Particularly, the study of community people's health in the extent an island area is almost rare as that personal and the material benefits in this area are lacking of community people's work is large, and the basic elements of living, such as diet and elimination, are irregular due to the schedule of the tide. Thus, there are many potential health problems. In this regard, the study attempted to understand the health problems of island community people and to provide a basis for developing health promotion and health education programs. In collecting data for the study, face to face interviews were made through a structured questionnaire from October 1 to December 30, 1996. Collected data were analyzed with the SAS statistics program, descriptive statistics, t-test and ANOVA. Subjects' health status was examined by classifying into such categories as their health perception, complaints of health problem, related lifestyle, psychosocial health staus, the result of examination is as follows; 1. For subjects' health perception, 26.9% of the subject answered not sick, but not so healthy'; 30.9% thought they were healthy, while 22.9% answered that they were not healthy. 2. For the health problem complaints many complained of pains in their muscles and skeletal system, especially knee joint pain. Women's health problems related with breast and the reproductive system included 52.3% of cases doing breast self examination, while 56.55% received the cervical cancer screening test. In men's health problems, 44.2% of subjects answered that they have moderate to severe BPH(Benign Prostatic Hypertrophy) symptom. 3. There were statistically a significant difference in the degree of physical health according to marital status(p=0.0028), occupation(p=0.0442), income(p=0.0357). 4. For stress status, 17.2% was to need the intervention, 50.2% was to need observation. 5. The mean score of self-esteem was 27.7 showing a relatively high score. 6. For the rate of smoking, 37.7% used to smoke, while 28% used to take alcohol. 7. The rate of substance abuse was 45.9% of subjects. 8. Most of subjects' health behaviors included most of the acupuncture (52%). 9. The rate of subjects receiving comprehensive medical testing was 34.36% while 34.78% did after care managing behavior. 10. For the obesity grade, 53% is normal weight, low-weight 32.8%, obesity 33%. 11. For nutrition status, 78.7% illy balanced to need intervention of nutritional education. 12. For 78.7% of subjects, muscle strength and 40.7% of stretching were not good enough to need health education on physical exercises. Therefore, based on the results, appropriate health education programs need to be developed to promote health of community people on an island.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.31 no.3
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• pp.23-30
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• 2003

In this study, the various load cases by specified by the IEC61400-1 international specification and GL Regulations for the wind energy conversion system were considered, and a specific composite structure configuration which can effectively endure various loads was proposed. In order to evaluate the structure, the structural analysis for the composite wind turbine blade was performed using the finite element method(FEM). In the structural design, the acceptable configuration of blade structure was determined through the parametric studies, and the most dominant design parameters were confirmed. In the stress analysis using the FEM, it was confirmed that the blade structure was safe and stable for all the considerd load cases. Moreover the safety of the blade root joint with insert bolts, newly devised in this study, was checked against the design loads and also the fatigue loads. The fatigue life for operating more than 20 years was estimated by using the well-known S-N linear damage rule, the load spectrum and Spera's empirical equations. The full-scale static test was performed under the simulated aerodynamic loads. from the experimental results, it was found that the designed blade had the structural integrity. Furthermore the measured results were agreed with the analytical results such as deflections, strains, the mass and the radial center of gravity. The studied blade was successfully certified by an international institute, GL, of Germany.

• Toxicological Research
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• v.33 no.3
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• pp.225-231
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• 2017

National reference standards (NRSs) for biologics are established through potency estimation by a multi-center joint study of standard materials used in the approval process for national lot release and quality control of vaccines, blood products, and other biologics. In this study, a stability evaluation was conducted to determine whether the potency of NRSs for six blood products was being maintained at a consistent level in Korea. The present study conducted real-time stability tests via in-vivo/in-vitro bioassay on NRSs for blood coagulation factor VIII concentrate (2nd standard), antithrombin concentrate, prekallikrein activator, anti-hepatitis B immunoglobulin, blood coagulation factor IX concentrate, and anti-tetanus human immunoglobulin, as well as a trend analysis using cumulative annual results. The real-time stability test results showed that the mean potency of six NRSs was all within the control limit. In the trend analysis, the potency of NRS for blood coagulation factor VIII concentrate (2nd standard) showed a decreasing trend, while the potency of all other products had been stably maintained. The present study confirmed that the mean potency of NRSs for six blood products had been stably maintained in Korea. The findings of the present study establish a foundation that can ensure the quality of NRSs for biologics in Korea, and it is expected to make a major contribution to the supply of high-quality biologics.

• Journal of the Korean Wood Science and Technology
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• v.27 no.1
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• pp.30-36
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• 1999

This paper describes the relationship between the bending strength properties of sloped finger-jointed woods and the acoustic emissions (AEs) generated during the test. Pinus densiflora pieces were cut in sloped-finger types and glued with four kinds of adhesives (polyvinyl acetate, polyvinyl-aeryl, oilic urethane and resorcinol-phenol resin). The results were as follows: The lower the bending strength(load) was, the earlier the generation time of AE event count got and the higher the increasing rate of AE event count became in the sloped finger-jointed specimens bonded with polyvinyl acetate and oilic urethane resin adhesives. Therefore, the slope from load-AE cumulative event count curve was very steep. The AE event count for resorcinol-phenol resin adhesive obtained even from low load level was abundant. The AE event count continuously increased as load increased and the event count was much more than one in the other conditions. The slope from load-AE cumulative event count curve was very gentle compared with other conditions. The patterns of AE event count and count were very similar. The relationship between the MOR and the AE parameter from load and AE cumulative event count in the early stage of the sloped finger-jointed specimens bonded with polyvinyl acetate, oilic urethane and resorcinol-phenol resin adhesives was much greater than that between the MOE and the MOR. Therefore, the AE signals obtained during bending test are useful for estimating the strength of sloped finger-jointed specimens.

• International Journal of Highway Engineering
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• v.8 no.3 s.29
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• pp.105-114
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• 2006

A popular alternative to extend the life of aged pavement is asphalt overlay. However, it has a very serious and inherent shortcoming in deterring a reflection crack. Although joint-rehabilitation and stress-relief techniques have been applied to deter such reflection cracks in aged pavement, the techniques had a limited success only in slowing down the progress of a reflection crack. Rubblization technique rubblizes the concrete pavement slab in situ and uses the rubblized slab as the base material. Then, pavement overlay is applied to finish off the rehabilitation of aged pavement. This rubblization technique has the advantage of solving the problem of reflection cracking completely. When rubblization technique is applied, the upper layer of aged concrete pavement is rubblized between 40mm-70mm in depth. However, the lower layer is typically rubblized more than 100mm in depth. Nevertheless, it is difficult to turn the entire concrete pavement of more than 30cm in depth into rubblized aggregate of appropriate size. Thus, a simulation experiment was carried out to find the appropriate rubblized depth, which avoids the reflection cracking and still maintains the function of subbase, by varying the depth of rubblized depth in loom increments of 0cm, 10cm, and 20cm. The result indicated the optimum rubblized depth was 10cm (Lee, 2006). Additionally, a small rubblizinge equipment was developed in order to derive the rubblization technique appropriate for thick concrete pavement. This equipment was tested out on an experimental pavement, which was constructed with the same standard and specification for the road in actual use, by varying its rubblizing head shape and energy as well as the effective area of rubblization. This experiment led to a prototype equipment for rubblization of thick concrete pavement. The prototype was put into use on a highway, undergoing a test construction and monitoring afterwards. This entire process was necessary for the validation of the proposed rubblization technique.