• International Journal of Highway Engineering
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• v.15 no.6
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• pp.25-32
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• 2013

PURPOSES : The purpose of this study is to provide the method of how to measure the coefficient of thermal expansion of concrete using temperature compensation principle of electrical resistance strain gauge. METHODS : The gauge factor compensation method and thermal output(temperature-induced apparent strain) correction method of self-temperature compensation gauge were investigated. From the literature review, coefficient of thermal expansion measurement method based on the thermal output differential comparison between reference material(invar) and unknown material(concrete) was suggested. RESULTS : Thermal output is caused by two reasons; first the electrical resistivity of the grid conductor is changed by temperature variation and the second contribution is due to the differential thermal expansion between gauge and the test material. Invar was selected as a reference material and it's coefficient of thermal expansion was measured as $2.12{\times}10^{-6}m/m/^{\circ}C$. by KS M ISO 11359-2. The reliability of the suggested measurement method was evaluated by the thermal output measurement of invar and mild steel. Finally coefficient of thermal expansion of concrete material for pavement was successfully measured as $15.45{\times}10^{-6}m/m/^{\circ}C$. CONCLUSIONS : The coefficient of thermal expansion measurement method using thermal output differential between invar and unknown concrete material was evaluated by theoretical and experimental aspects. Based on the test results, the proposed method is considered to be reasonable to apply for coefficient of thermal expansion measurement.

• The Journal of the Korean dental association
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• v.51 no.6
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• pp.330-336
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• 2013

Considering the high prevalence, transverse control in adult patients presenting relatively narrow maxillary width is a challenging issue. This study compared the pattern of arch expansion induced by either miniscrew-assisted rapid palatal expander (MARPE) or continuous archwire engaged on self-ligating brackets. Age-matched adults groups(N=15 each) were treated with respective appliance. In both groups, all intercanine, interpremolar, and intermolar widths increased, and significantly greater change was noted in the intermolar region. Buccal tipping was minimal in both groups. Subsequent arch length increase, lingual tipping of incisors and distal tipping of molars were also found in both groups. According to the results, it can be concluded that the MARPE induced generally more arch expansion, particularly in the intermolar width, indicating that the adults showing buccal crossbite of the molars may have to undergo expansion via MARPE prior to arch alignment using continuous archwire.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2004.03a
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• pp.228-233
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• 2004

The spray and acoustic characteristics by the self-oscillation of a swirl coaxial injector were experimentally studied. The self-oscillation of a swirl coaxial injector is defined as pressure and flowrate oscillations by a time-delayed feedback between liquid and gas phase and has strong influences on atomization and mixing processes. Hence the occurrence and effect of the self-oscillation are measured using shadow photography technique, acoustic test and PDPA. The occurrence of self-oscillation largely depends on the injection conditions, such as pressure drop of liquid phase and relative momentum ratio. From the experimental results, self-oscillation occurs when the momentum of gas phase is enough large and the smaller the pressure drop of liquid phase is, the better self-oscillation occurs at the same momentum ratio. The self-oscillation is also affected by injector geometries, increasing the recess length results in the expansion of self-oscillation region and the increase of sound pressure level. The self-oscillation of a swirl coaxial injector accompanies a high intensity scream and this scream may provide harmful disturbances to combustion processes. Self-oscillation leads to strong changes in the drop size distribution and smoothly varies the slope of radial SMD distribution.

• The Journal of the Korea Contents Association
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• v.18 no.3
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• pp.499-508
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• 2018

This study explored the relationship between the Resilience and Organizational commitment, The police officers' perception on the resilience has been measured, and then how their perception on the resilience affects the organizational commitment has been examined. This study aimed at measuring the effects of police officers' perception on the resilience on organizational commitment By reviewing previous finding, police officers' resilience(Self-Regulation Skills(Regulation skills, Cause Analysis skills, Impulse control skills), Interpersonal Skills(Expansion skills, Communication skills, Empathy skills), Positive Capacity(Appreciate, Life satisfaction, Self-optimism)) were selected as independent variables, Organization Commitment(Affective commitment, Continuance commitment, Normative commitment) was selected as dependent variable. The result of analysis showed that Life satisfaction>Cause Analysis skills>Communication skills> Empathy skills> Appreciate> Impulse control skills influenced in Affective commitment (positive), Life satisfaction>Self-optimism>Regulation skills>Communication skills>Cause Analysis skills in Continuance commitment(positive), and Expansion skills>Empathy skills>Self-optimism>Life satisfaction>Impulse control skills in Normative commitment (positive).

• International Journal of Advanced Culture Technology
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• v.7 no.2
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• pp.103-112
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• 2019

Online self-disclosure was hypothesized as a mediating variable, explaining the relationship between Facebook access motivation (relationship expansion, curiosity about others' life, maintenance of social connection, social pressure from others, habitual use, impression management, searching for information, and content sharing) and Facebook addiction. Data came from 407 high school students in the Busan, and Gyeongnam provinces. Structural analysis was used to specify the relations among measured construct. Facebook access motivation of curiosity about others' life, Facebook access motivation of maintenance of social connection, Facebook access motivation of social pressure from others, Facebook access motivation of habitual use, and Facebook access motivation of impression management were significant predictors of Facebook addiction. Online self-disclosure mediates between Facebook access motivation of curiosity about others' life, Facebook access motivation of social pressure from others, Facebook access motivation of searching for information & Facebook access motivation of content sharing and Facebook addiction. Viewing online self-disclosure as a mediator has important implications for social media addiction counseling practice.

• KDI Journal of Economic Policy
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• v.44 no.2
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• pp.45-71
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• 2022

This paper studies potentially relevant factors affecting changes in the number of self-employed in Korea during the period of 1986-2018. The number of self-employed had increased steadily until 2002 but started to decrease around that time and had continued to decline. The increasing trend in the number of self-employed during 1986-2001 is mostly explained by demographic changes, whereas the declining trend during 2002-2018 cannot be explained by demographic factors. In this study, I consider four institutional factors that potentially affect the decrease in the number of self-employed after 2002: i) a decrease in the job-separation rate of wage workers, ii) an increase in the income tax rate applied to the self-employed, iii) an increase in minimum wages, iv) an expansion of unemployment insurance benefits. Using a search and matching model with the self-employed, I quantify the effects of these four factors on the decrease in the number of self-employed during 2002-2018. Quantitative results show that the impact of the increase in the minimum wage is relatively large, whereas the effects of the other three factors are limited. The increase in the minimum wage accounts for approximately 17.5% (0.169 million) of the decrease in the number of self-employed during 2002-2018 (0.964 million).

• 제어로봇시스템학회:학술대회논문집
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• 1986.10a
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• pp.90-94
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• 1986

This paper describes expansion of the state space pole assignment self-tuning control of SISO systems with system noise and abservation noise to that of MIMO systems. Resursive Prediction Error method is used for both parameter and state estimation in the block controllable canonical form. This simplifies the state feedback law by eliminating the online computation of transformation matrix.

• Journal of Oriental Neuropsychiatry
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• v.32 no.2
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• pp.129-140
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• 2021

Psychotherapy in Korean Medicine is characterized not only by management of mental issues, but also a holistic perspective of the mind and body, which includes physical treatment. In this case report, we describe the efficacy of Korean psychotherapy for couples with physical symptoms of heartache, emotional tension and marital relationships by addressing the challenges at the Mind and Body levels. For the physical treatment of the couple, the wife was treated with a Bunshimgi-Eum and the husband was administered a Cheonwangbosimdan, combined with a psychiatric interview based on Korean Medicine. It involves listening to the couple's story, YiJungBeongi therapy, understanding and learning about vases and defense mechanisms, self-understanding and understanding of the husband through self-understanding and expansion, and husband's understanding of the wife's position, self-interpretation and acceptance. Based on counseling, the couple's personal characteristics and expansion for self-growth, the progress and results of the couple's challenges and relationship improvement in a relatively short period of time are presented. In response, we hope that the evidence based on Korean Psychotherapy supporting the counseling for couples will continue to accumulate. We would like to report and share a few opinions.

• Steel and Composite Structures
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• v.49 no.6
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• pp.615-631
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• 2023

To investigate the seismic behavior of steel slag self-stressing concrete-filled circular steel tubular (SSSCFCST) columns, 14 specimens were designed, namely, 10 SSSCFCST columns and four ordinary steel slag (SS) concrete (SSC)-filled circular steel tubular (SSCFCST) columns. Comparative tests were conducted under low reversed cyclic loading considering various parameters, such as the axial compression ratio, diameter-thickness ratio, shear-span ratio, and expansion ratio of SSC. The failure process of the specimens was observed, and hysteretic and skeleton curves were obtained. Next, the influence of these parameters on the hysteretic behavior of the SSSCFCST columns was analyzed. The self stress of SS considerably increased the bearing capacity and ductility of the specimens. Results indicated that specimens with a shear-span ratio of 1.83 exhibited compression bending failure, whereas those with shear-span ratios of 0.91 or 1.37 exhibited drum-shaped cracking failure. However, shear-bond failure occurred in the nonloading direction. The stiffness of the falling section of the specimens decreased with increasing shear-span ratio. The hysteretic curves exhibited a weak pinch phenomenon, and their shapes evolved from a full shuttle shape to a bow shape during loading. The skeleton curves of the specimens were nearly complete, progressing through elastic, elastoplastic, and plastic stages. Based on the experimental study and considering the effects of the SSC expansion rate, shear-span ratio, diameter-thickness ratio, and axial compression ratio on the seismic behavior, a peak displacement coefficient of 0.91 was introduced through regression analysis. A simplified method for calculating load-displacement skeleton curves was proposed and loading and unloading rules for SSSCFCST columns were provided. The load-displacement restorative force model of the specimens was established. These findings can serve as a guide for further research and practical application of SSSCFCST columns.

• Korean Journal of Agricultural Science
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• v.27 no.2
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• pp.141-157
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• 2000

This study is aimed at identifying the socio-economic value of the total area of 23,500ha of paddy field which will be reclaimed in year 2003. In Korea, tidal land reclamation projects has been carried out not only for paddy field expansion to meet national food security but also for national land expansion to cope with the shortage of land supply in implementing urbanization and industrialization. As of end of 1999, 75,738ha of tidal land reclamation, 48.3%, out of 156,666ha has been carried out in Korea. In spite of continuous implementation of tidal land reclamation, 48.3%, out of 156,666ha has been carried out in Korea. In spite of continuous implementation of tidal land reclamation projects, the appraisal of the national land expansion value has not been made even though the severe competitiveness of land use in economic development. Agricultural land about 20,000 - 30,000ha per year has been converted to urban and industrial land and the converted areas have been produced higher added value than that of the farm land. Accordingly, farm land expansion equivalent to the converted area have to be reclaimed to cope with the food shortage and security in the future. In relation to the study, demand and supply of rice, the staple food of Korean, has been projected up to year 2025. The study results are as follows: 1. Under the assumption of continuing the present tendencies of rice consumption, population increase, farming practices and farm land conversion, paddy area requirement to meet self sufficiency of rice were forecasted as 136,950ha in 2015, 193,460ha in 2020 and 218,482ha in 2025 respectively. 2. The average converted price of paddy per pyeong in Kimje city, Puna Gun and Gunsan city was estimated at 241,150won and average farm land price was amounted to 63,760won. The differential rent was estimated at 177,400won per pyeong which was used as a criteria for valuation of national land expansion effect of the tidal land reclaimed by Saemangeum project. The total land rent of 23,250ha expanded by tidal land reclamation was amounted to 12,361 billion won. Annual expected value of the expanded national land was estimated at 988.9 billion won considering 8% of annual discount rate in Korea. 3. Tidal land resource for paddy area development is limited comparing with the future requirement of paddy area to cope with self sufficiency of rice consumption. Accordingly farm land conversion to urban and industrial land should be regulated and protected in the sense of sustainable development in the future.