• Journal of the Korea institute for structural maintenance and inspection
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• v.19 no.5
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• pp.56-66
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• 2015

This study aims at developing a new seismic resistant method by using precast concrete wall panels for existing low-rise, reinforced concrete beam-column buildings such as school buildings. Three quasi-static hysteresis loading tests were performed on one unreinforced beam-column specimen and two reinforced specimens with U-type precast wall panels. Seismic resistant test of anchored and welded steel plate connections manifested an average of 2.8 times increase in the maximum loading (average 591.8 kN) in comparison to unreinforced beam-column specimen. The maximum drift ratios were also shown between 1.4% and 2.7%. An analytical study was performed while assuming the RC column on the right side and the vertical element of the reinforced PC panel to behave in completely composite manner and the RC column on the left side and PC panel to behave in completely non-composite manner when loading was exerted from upper right end of RC frame of specimen to its left side. It was found with the assumptions that the overall flexural behavior in principle agreed with the experimental result.

• Journal of the Korean Institute of Gas
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• v.12 no.2
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• pp.69-76
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• 2008

Three failure cases of CNG composite vessels were reported since after January 2005. The 1st and 2nd accidents were indebted to vessel defect and installation mistake. The 3rd was caused by gas leak at pipe connections. In this paper various aspects were studied based on information of the three failure analysis, which must be improved for better safety of the CNG bus system. Overpressure region caused by vessel explosion was theoretically predicted and also assessed by PHAST program. Explosion of 120 l vessel under 20 MPa is equivalent to 1.2 kg TNT explosion. The predicted value by PHAST was more serious than theoretical one. However, actual consequence of explosion was much less than both of the predicted consequences. Since the CNG vessel was designed by the performance based design methodology, it is difficult to verify whether the required process and tests were properly conducted or not after production. If material toughness is not enough, the vessel should be weak in brittle fracture at early in the morning of winter season since the metal temperature can be lower than the transition temperature. If autofrettage pressure is not correct, fatigue failure due to tensile stress during repeated charging is possible. One positive aspect is that fire did not ocurred after vessel failure. This may be indebted to fast diffusion of natural gas which hindered starting fire.

• Korean Security Journal
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• no.16
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• pp.101-118
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• 2008

The subjects in this study were 500 students who were selected from a population that consisted of security majors who took courses in martial arts in four different four-year-course universities. After a survey was conducted, the answer sheets from 451 students were analyzed except 49 incomplete ones. The collected data were analyzed with SPSS Ver. 12.0 program. Frequency analysis, t-test and one-way ANOVA were utilized, and LSD and regression analysis were employed to make a post-hoc comparison. All the hypotheses formulated in this study were verified at the a=.05(Chronbach's alpha) level of significance. The findings of the study were as follows: First, as for relations between demographic characteristics and self- realization, the college students investigated were statistically different according to gender in three subvariables of self-realization that included ability development, ability display and attainment of ideal. Age and academic year made a significant difference to their ability development and attainment of ideal, and they differed statistically significantly in terms of ability development according to black lebel test. Second, concerning connections between the degree of martial-arts training and self-realization, training term, one of the subvariables of the degree of martial-arts training had a positive correlation to their ability development and attainment of ideal at the 5% level of significance, and training time was positively correlated to their ability development at the 5% level of significance. Third, training term, one of the subvariables of the degree of martial- arts training, had an impact on ability development, and that exerted a firsthand influence on attainment of ideal as well.

• Journal of Korean Society of Steel Construction
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• v.17 no.4 s.77
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• pp.419-429
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• 2005

The objective of this study is to clarify the structural features of members consisting of a connection, as part of the previous study on the CFT column-to-beam tensile connection with a combined cross diaphragm. This connection has the following merits: it evenly distributes the stress on the beam flange and the diaphragm and reduces the stress concentration by improving the stress transfer route and restraining the abrupt deformation of the diaphragm. Finite element analysis was performed to find out the stress transfer through the sleeve, which is an important member of the connection with a combined cross diaphragm. The length and thickness of the sleeve were used as variables for the analysis. The analysis results showed that the length and thickness of the sleeve did not influence the capacity of the connection and played the role of a medium for the transfer of the stress from the diaphragm to the filled concrete. It was proposed that the appropriate length of the sleeve have the same value as the diameter of the sleeve and that the appropriate ratio of the sleeve diameter to the sleeve thickness be 20. Two equations for the evaluation of the load carrying the capacity of the connection were also proposed through the modification of the evaluation equation suggested in the previous study.

• Journal of Korean Society of Steel Construction
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• v.15 no.6 s.67
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• pp.683-691
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• 2003

Recently, the steel has been increaseingly used as an integrated part of high-rise buildings, which often composed of steel structures, steel reinforced concrete structures and composite structures. The steel base is designed to transfer the stresses induced from steel column to the reinforced concrete footing through the base plate. However, in the design of steel structures and steel reinforced concrete structure, it is generally difficult to evaluate the bearing strength of the steel base subjected to large axial force. Furthermore, the material used in steel base is quite different from those used in other connections and a load transferring mechanism of steel base is very complicated in nature. Therefore, a special attention must be placed in design and construction of steel base. In generally, the bearing strength test and research of the steel base subjected to concentrated load are carried out. But, in the design of the structures, uniaxial eccentric load is loaded to the steel base of the steel structures. In this research, the bearing strength and the me of failure considering eccentric loads and eccentric length, were experimented when eccentric load is loaded to the steel base of steel structures. Based on the test results, a basic design reference is suggested for a reasonable design of steel structures, steel reinforced concrete structures and composite structures.

• Korea journal of population studies
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• v.33 no.2
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• pp.61-84
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• 2010

The goals of the study were to examine if and how exposure to suicidal factors in social relationships affects suicidal ideation and behaviors and also analyze how family factors are associated with suicidal ideation and behavior. Data drawn from Korean General Social Survey(KGSS) collected in 2009 were analyzed. The findings show that exposure to the suicidal factors have statistically significant effects on suicidal ideation and behaviors. In the findings, respondents who have experiences of which socially close persons have suicidal ideation or completed suicide are more likely to have suicidal ideation and suicidal plan even in the models for which demographic factors and depressive symptoms are controlled. Also, family factors have significant effects on suicidal ideation and suicidal behaviors. Family stress increases suicidal ideation and behaviors whereas expectation on family support reduces the likelihood of having suicidal ideation and behaviors. This study shows that there might be possibility of behavioral contagion in terms of suicide through social connections and family has both positive and negative aspects on suicidal ideation and behaviors. Our study suggests policy implications for people who were exposure to suicide.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.35 no.3
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• pp.175-186
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• 2017

In this study was to survey method of national/public land actual condition survey to utilization of UAV, in order to evaluate the economic and accuracy. we carried out the comparative evaluation of the cadastral status surveying in terms of accuracy of parcel checkpoint, economical costs. The results are summarized as follows. First, average position error of the orthoimage was 0.033m in X error, 0.023m in Y error when the RMSE average calculated 0.046m from the intersection of plane distance connections. Secondly, it was appeared the accuracy of the orthophotograph is 0.076m at the maximum RMSE of the UAV orthoimage check point and 0.042m at the minimum RMSE compared with the VRS-GNSS survey results. Thirdly, when the allowable error specified in the implementing regulation of the current cadastral survey is applied, all of the checkpoint of 0.360m tolerance corresponding to the scale of 1/1,200 is satisfied. Finally, UAV utilization method in national/public land actual condition survey is 26,497,436(KRW) cheaper than cadastral survey method for In the economic evaluation of national/public land actual condition survey. Therefore, as a result of this study shows that the method of utilizing UAV in the national/public land actual condition survey satisfies legal standards in terms of accuracy and economical aspect is a way to further reduce the local government budget.

• The KIPS Transactions:PartD
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• v.11D no.4
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• pp.783-798
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• 2004

An e-business client application in ubiquitous mobile computing environment may become disconnected from the enterprise server due to broken communication connections caused by the limitation of mobile computing environments(limited battery life of the mobile device, low bandwidth communication, incomplete wireless communication infrastructure, etc). It Is even Possible that mobile client application Intentionally operates in disconnected mode to reduce communication cost and the power consumption of the mobile device. We use “data hoarding” as a means of providing local autonomy to allow transactions to be processed and committed on the mobile host despite of disconnection. The key problem to this approach is the synchronization problem that serialize potentially conflicting updates from disconnected clients on master objects of the server database. In this paper, we present a new transaction synchronizing method that splits a transaction into a set of independent component transactions and give the synchronization priority on each component taking the possibility of use and conflicts in the server into consideration. Synchronization is performed component by component based un synchronization priority. After the Preferred component of a no bile transaction succeeds in synchronization with the server, the mobile transaction can pre-commit at server. A pre-committed transaction's updated value is made visible at server before the final commit of the transaction. The synchronization of the component with low synchronization priority can be delayed in adaption to wireless bandwidth and computing resources. As a result, the availability of important data updated by mobile client is increased and it can maximize the utilization of the limited wireless bandwidth and computing resources.

• Journal of dental hygiene science
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• v.9 no.5
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• pp.545-550
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• 2009

This study set out to examine the knowledge about and preventive actions against musculoskeletal diseases among dental hygiene students according to the Health Belief Model, suggest a need for programs to promote health and prevent those diseases, and investigate their relations, A survey was taken among 83 sophomores and 114 juniors at the dental hygiene major of a college in Gyeonggi Province. Analyzed by using SAS 8.0 version. The findings are as follows: 1. The sophomores and juniors scored $22.50{\pm}2.37$ and $22.29{\pm}3.01$ points, respectively, on susceptibility of the Health Belief Model with significant differences between the two groups(P < 0.01). Significant differences were also found between the sophomores that scored $18.82{\pm}2.60$ points and the juniors that scored $18.64{\pm}2.77$ points on benefit(P < 0.05). 2. The juniors experienced a higher level of pain than the sophomores with statistical significance observed on the neck, shoulder, lower back, knee, foot, and ankle(P < 0.05). 3. Of the Health Belief Model, severity had significant positive correlations with 'Placing frequently used tools near the dental technician' and 'Trying to avoid repeating the same task and diversify tasks'(P < 0.01). And benefit was positively correlated with 'Trying to reduce the frequency of bending and stretching out during treatment, 'Trying not to lean much with the neck, back, arm, and wrist' and 'Trying to maintain the torso in the neutral position'(P < 0.01). The results suggest that there should be some instructions to help dental hygiene students practice the preventive actions against musculoskeletal diseases and further prevention programs against those diseases.

• Journal of Korean Society of Transportation
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• v.23 no.2
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• pp.75-82
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• 2005

To relieve congestion in the current system of intercity transportation, the Korea decided in 1990 to construct a high-speed railroad between Seoul and Busan and it is now in operation. This new mode of transportation significantly cut travel time between major cities and a trip from Seoul to the southeastern port of Busan. Since the KTX opening, average daily passenger numbers on both the Gyeongbu and Honam lines have increased about 1.3 fold over 2003 levels. As of December 2004, the KTX trains are carrying about 81,000 people a day. On KTX routes, the daily number of airline passengers dropped. Express long-distance bus traffic also dropped by 20% to 30%, while that on short-distance routes (100km or less) increased by about 20%. These figures clearly indicate that the Korean transportation network is becoming railroad-centric. However, the number of KTX passengers is fewer than anticipated possibly due to the Korean economic downturn and the operation of the KTX will leave many existing Saemaul and Mugunghwa train sets idle, which will be put into operation for areas, not covered by the KTX. When all the existing major lines have been electrified, more high-speed rail services will be phased in using direct connections to maximize operational efficiency. And also, the dual management by KTX and conventional rail will be regarded as the promotion of the benefit of the public.