• Journal of the Korea Institute of Building Construction
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• v.23 no.6
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• pp.715-726
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• 2023

This study suggested that protective panels should be installed as sacrificial members as a safety design method for structures with potential explosions such as hydrogen charging stations to minimize direct damage to the structure and have resilience. To this end, the focus of the experiment is on quantitatively evaluating the impact of the structure when the protection panel is installed closely or spaced apart from the structure in a high-speed collision situation of the projectile. The experimental design used steel plates instead of concrete structural members mainly used in the past for excellent reproducibility, and the impact of structural members was compared and analyzed through deformation differences on the back of the steel plate. In addition, the impact of changes in the physical properties of the elastic body used as a separation material for the protective member and the difference in shock wave transmission time according to the protective member and the elastic body on the structural member was investigated.

• The Journal of the Petrological Society of Korea
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• v.16 no.3
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• pp.162-179
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• 2007

Macheon Layered Intrusion (MLI) which intruded into Precambrian gneiss complex of the northern Jirisan area, southeastern part of Youngnam (or Sobaeksan) Massif, is a layered mafic-ultramafic complex of Triassic age (ca. 223 Ma). The MLI is divided into Layered Series and Laminated Series. Layered Series is subdivided into Central Zone (Lower Zone) consisting of olivine gabbros and Peripheral Zone (Middle or Upper Zone) consisting of hornblende gabbros based on the type of cumulus texture and the main mafic phase. The Central Zone of Layered Series comprises thinly laminated olivine gabbros and uniform or thickly laminated coarse olivine gabbros which consist of mela-gabbro, troctolite, leuco-troctolite, and anorthositic rocks. Laminated Series is also subdivided into quartz-bearing biotite-pyroxene gabbros and homblende diorite and both have variable amount of interstitial quartz and microcline. Laminated series display moderately to slightly developed igneous lamination which is defined by the planar alignment of lath-shape plagioclases. Chilled margin of quartz-bearing biotite-pyroxene gabbro with surrounding Precambrian gneisses insists shallower intrusion of more felsic cognate magma evolved in the deep a little later. Rocks of Layered Series have orthocumulus to adcumulus olivine, adcumulus to intercumulus plagioclase, and intercumulus to heteradcumulus pyroxene and hornblende. Magmatic modally grading, folding, and cross-lamination are not rarely occurred in thinly layered rocks. These textural characteristics define main mechanisms of the formation of layered and laminated structure in mafic-ultramafic rocks of Macheon Layered Intrusion are gravity settling and in-situ crystallization associated with slumping and density current.

• Journal of the Korea Concrete Institute
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• v.15 no.2
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• pp.335-343
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• 2003

In the previous experimental study, it is verified that the ultimate strain of concrete (${\varepsilon}$$_{cu}$=0.003) and coefficient of equivalent stress block (${\beta}$$_1$) can be used for the analysis of RC beams under biaxial and uniaxial bending moment. However, the characteristics of stress distribution of non rectangular compressed area in the RC columns are different to those of rectangular compressed area. The properties of compressive stress distribution of concrete have minor effect on the pure bending moment such as beams, but for the columns subjected to combined axial load and biaxial bending moment, the properties of compressive stress distribution are influencing factors. Nevertheless, in ACI 318-99 code, the design tables for columns subjected to axial loads with bidirectional eccentricities are based on the parameters recommended for rectangular stress block(RSB) of rectangular compressed areas. In this study the characteristics of stress distribution through both angle and depth of neutral axis are observed and formulated rationally. And the modified parameters of rectangular stress block(MRSB) for non rectangular compressed area is proposed. And the computer program using MRSB for the biaxial bending analysis of RC columns is developed and the results of MRSB are compared to RSB and experimental results respectively.

• International Commerce and Information Review
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• v.15 no.4
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• pp.391-418
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• 2013

The development of web 2.0 technologies created the popularization of social media. People use social media for information communication with many purposes. Under such an environment, this paper examines the acceptance of word-of-mouth information dissemination through social media. The determinants of acceptance and the effect of acceptance on purchase intention as the result of information on social media pertaining to overseas tourism are researched in detail. The consumer choice for international travel involves a decision making with high uncertainty and thus people are using the word of mouth information strongly. Empirical analysis using SPSS, AMOS analysis software was performed on sample data consisting of 385 collected surveys. This paper shows the neutrality of eWOM, the professionalism of senders, and that the practicability of eWOM significantly affects the acceptance of the information. In addition, the acceptance of eWOM information has a significant effect on the spread of eWOM and customers' purchase intention. The paper shows that the practicability of information and the professionalism of word-of-mouth information should be improved.

• The Korean Journal of Elementary Counseling
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• v.11 no.2
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• pp.279-298
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• 2012

The purpose of this study was to explore the different perceptions of relationship with significant others of multicultural children with PTSD symptoms. To select the subjects for this study, Korean version of Greenwald and Rubin's CROPS(Child Report of Post-traumatic Symptoms) was administered to 97 multicultural children and 110 Korean children. Among them 20 multicultural children and 22 Korean children were determined as children with PTSD symptoms. SCT was administrated to 42 children and the content analysis of 42 SCTs was undertaken. The following results are the major findings of this research: a) multicultural children perceived their mothers, fathers, friends, and teachers more negatively than Korean children; b) only 55% of multicultural children had positive self-images while almost Korean children had positive self-images; c) multicultural children expressed psychological trauma from peers in school while Korean children expressed psychological trauma from parents at home. Lastly, we discussed implications of the results, limitations and suggestions for future study.

• Korean Chemical Engineering Research
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• v.54 no.5
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• pp.687-692
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• 2016

Biomass has been concerned as one of the alternative energy resources because it is renewable, abundant worldwide, eco-friendly, and carbon neutral. Quercus variabilis has been studied to understand pyrolysis reaction characteristics, and to evaluate the efficiency of bio-energy production from fast pyrolysis. Quercus variabilis were fast pyrolyzed in a bubbling fluidized bed reactor at various reaction conditions. The effects of pyrolysis temperature between $400^{\circ}C$ and $550^{\circ}C$ on product yields were investigated. The yield of bio-oil was changed between 36.98 wt% and 39.14 wt%, and those of gas yield was 33.40 and 36.96 wt% with increasing reaction temperature. The higher heating value (HHV) of bio-oil at $500^{\circ}C$ ($3.0{\times}U_{mf}$) was 20.18 MJ/kg. The gas compositions were similar for all reaction conditions such as CO, $CO_2$ and $CH_4$, and $CO_2$ selectivity was the highest (37.16~50.94 mol%). The bio-oil has high selectivities for furfural, phenol and their derivatives such as 1-hydroxy-2-propanone, 2-methoxy-phenol, 1,2-benzendiol, 2,6-dimethoxy-phenol.

• Journal of the Korean Institute of Gas
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• v.16 no.5
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• pp.14-20
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• 2012

Biogas can be obtained from biogenic materials through an anaerobic digestion process. Since biogas has low calorific value and its composition significantly varies, appropriate combustion strategies need to be established to obtain stable combustion in engine applications. In this study, efforts have been made to investigate the effects of inert gas composition variations on engine performance and emissions. Results show that the MBT spark timing was advanced and $NO_x$ was reduced as the inert gas in the biogas rose. Moreover, $NO_x$ emission drop in $CO_2$ diluted biogas was more significant than that of $N_2$ due to higher heat capacity of $CO_2$, while THC emissions showed the opposite tendency. Thermal efficiency was increased in $N_2$ case with elevation of $N_2$ due to the decreased heat loss and PMEP. However, there is no difference in $CO_2$ case because of deteriorated flame propagation speed.

• Journal of the Korean Institute of Gas
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• v.15 no.5
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• pp.25-30
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• 2011

Biogas obtained from the biodegradable organic wastes in an anaerobic digester consists of $CH_4$ and inert gases such as $CO_2$ and $N_2$. Since the composition of biogas varies by anaerobic digester conditions and the origin of wastes, it is necessary to respond to these variations so as to make stable combustion and accomplish high efficiency when it is used as a fuel for power generating SI engines. In this study, efforts have been made to investigate the effect of changes in the calorific values of biogas on the engine performance and exhaust characteristics. The biogas was simulated by supplying of $CH_4$ with $N_2$ dilution of various ratios, and ECM was developed to achieve accurate control of ignition and combustion. The results show that as the $CH_4$ concentration of the biogas decreases, the optimal spark timing is advanced due to the elevated thermal capacity and lowered $O_2$ concentration of the in-cylinder charge. Furthermore, since combustion temperature was reduced by increased inert gas, $NO_x$ emissions decreased, whereas THC emissions increased.

• Korean Journal of Heritage: History & Science
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• v.53 no.3
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• pp.244-257
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• 2020

State-designated rain gauge pedestals, including a rain gauge support, were installed in front of the "Imunwon" at Changdeok Palace, made from various rock types. Some of those pedestals provide exact information on their production dates. These rain gauge pedestals are highly valuable as scientific instruments; however, there has been insufficient scientific research carried out on them. Therefore, precise analysis and conservative consideration are required. As a result of petrographic character analysis, the Changdeokgung rain gauge pedestal has been classified as marble. Furthermore, comparison of the results of P-XRF analysis with GSJ reference samples (JLs-1, JDo-1) has determined it to be dolomitic marble. Applying the same analysis to other state-designated rain gauge pedestals, it was presumed that the rain gauge supports at Gyeongsand-do Provincial Office and Gwansanggam were each made from aplite, pinkish medium-to-coarse biotite granite. Results confirmed that only the Changdeokgung rain gauge pedestal was made from marble. Marble is viewed as having an identity specificity rooted in a certain historical background. According to the tendency towards stone figures being made from marble, especially dolomitic marble, it is necessary to further studies whether particular rocks were used to make royal stone figures in Joseon Dynasty.

• Korean Journal of Cognitive Science
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• v.26 no.3
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• pp.357-375
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• 2015

In our daily life, the probability of target prevalence in visual search varies from very low to high. However, most laboratory studies of visual search used a fixed probability of target prevalence at 50%. The present study examined the properties of information processing during visual search where the probability of target prevalence was manipulated to vary from low (20%), medium (50%), to high (80%). The search items were made of simple shape stimuli, and search accuracy, signal detection measures, and reaction times (RTs) were analyzed for characterizing the effect of target prevalence on the information processing strategies for visual search. The analyses showed that the rates of misses increased whereas those of false alarms decreased in the search condition of low target prevalence, whereas the pattern was reversed in the high prevalence condition. Signal detection measures revealed that the target prevalence shifted response criterion (c) without affecting sensitivity (d'). In addition, RTs for correct rejection responses in the target-absent trials became delayed as the prevalence increased, whereas those for hits in the target-present trials were relatively constant regardless of the prevalence. The RT delay in the target-absent trials indicates that increased target prevalence made the 'quitting threshold' for search termination more conservative. These results support an account that the target prevalence effect in visual search arises from a shift of decision criteria and the subsequent changes in search information processing, while rejecting the account of a speed-accuracy tradeoff.