• Proceedings of the Korean Society of Toxicology Conference
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• 2001.10a
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• pp.123-124
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• 2001

DNA mutations undoubtedly contribute to the onset of some life style-related diseases including cancer. Rapid and reliable methods to detect DNA mutations and to isolate mutants should have a great impact on this field. Activated inflammatory leukocytes are considered to play some important roles in carcinogenesis by generating reactive oxygen species (ROS). The purpose of the present study is to examine the relationship between leukocyte activation by TPA and mutagenesis.(omitted)

• Journal of the Korean Society for Heat Treatment
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• v.25 no.4
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• pp.175-180
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• 2012

Role of Ca in grain growth behavior has been investigated in hot-rolled Al-3%Mg and Al-3%Mg-0.5%Ca wrought alloys. When annealed for 1 hr from 723 to 823 K, grain size of the Al-3%Mg alloy increased rapidly above 723 K, whereas grains were relatively stable up to 773 K for the Ca-containing alloy. Grain homogeneity of the Ca-containing alloy was better than that of the Ca-free alloy both in hot-rolled and annealed states. Calculated activation energies for grain growth were 77.6 and 85.9 kJ/mole in the range of 723 to 823 K for the alloys with 0 and 0.5%Ca, respectively. Taking SEM images and EDS results into account, enhanced thermal stability in response to Ca addition would be associated with Al4Ca compounds located along the grain boundaries, which eventually play a role in restricting grain growth at elevated temperatures.

• Journal of the Korean Home Economics Association
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• v.46 no.3
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• pp.87-101
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• 2008

This research was based on a case study of a child who experienced difficulties in ego development due to her mother's compulsive and depressed behavior. Twenty-four therapeutic play sessions, including 16 sessions involving sandplay, were conducted. Based on discussions by Neumann and Kalff, the child's early psychic development and ego development were observed during these sandplay. As part af this investigation, I conducted counseling sessions in the sandbox where the atmosphere was free and safe. The sessions were based on mother-child unity with the therapist. As a result, the child exhibited restoration of mother-child unity and showed the journey of constellation of self and ego development. The results of this research indicate the effectiveness of sandplay in accelerating ego development.

• The Journal of the Korean dental association
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• v.41 no.9 s.412
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• pp.631-636
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• 2003

Bacteria play a major role in the etiology of apical periodontitis. Traditionally it has been held the microorganisms are present in necrotic tissue in the root canal system and in tubules of the root dentin whereas the periapical tissues are free of bacteria. However, it is reported the presence of bacterial in the periapical lesions. They may form the biofilm and survive in the periapical tissues. Especially high incidence of biofilm is reported in the refractory periapical lesions. treatment was presented in the left maxillary first premolar with a long-standing fistula and apical calculus. Also. the role of biofilm and its treatment were discussed.

• Korean Journal of Child Studies
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• v.15 no.1
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• pp.23-35
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• 1994

This paper investigated children's learning process concerning age and gender, two of the most apparent social roles. The subjects of the study were 72 Korean preschool children between three to five years of age. The Study was designed to examine problems of developmental sequence and horizontal decalage in understanding of these social roles. Two five-step knowledge sequences of age growth and sex constancy were administered utilizing skill theory (Fischer, 1980). Each step in a sequence had different stories of age or sex role with increasing cognitive complexity, but the two sequences were equivalent in complexity. The children were tested under two different assessment conditions:high support condition of elicited imitation and low support condition of free play and the best story. The findings show that, the understanding of age and sex roles develops through the predicted five-step sequences. The understanding of age role seems to develop earlier than that of sex role although the developmental patterns of the two roles are similar. Variations in the children's performances under different conditions were dramatic, especially for the older children.

• Korean Journal of Child Studies
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• v.18 no.1
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• pp.23-38
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• 1997

This study investigated the difference between infant verbal and nonverbal interactions with a partner (teacher or peer). The subjects were 20 two-year-old infants 00 boys and 10 girls, mean age 31.3 months). Verbal and nonverbal interactions were videotaped during one hour of indoor free play per child in the Center. In verbal interaction, (1) boys spoke to themselves more than girls did, and (2) girls gave orders (imperatives, requests, and prohibitions) to peers and teachers more than boys did. In non-verbal interactions, (1) girls nodded to teachers more than boys did, (2) boys came closer to peers more than girls did, and (3) girls refused by gestures to peers more than boys did. In conclusion, the majority of the boys could be classified as peer-oriented and physically active in their interactions.

• Proceedings of the Korean Magnestics Society Conference
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• 2013.12a
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• pp.90-90
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• 2013

Since discovery, NdFeB permanent magnet has replaced application of the conventional magnets rapidly because of its superior physical and mechanical properties. With increasing consumption of power combined with energy resource depletion, energy efficiency is becoming more and more inportant. According to recent reports, almost almost half of the electric power is consumed by motor, and NdFeB magnets which are the core component of the motor play a key role on improving energy efficiency of the devices. In parallel with finding alternatives energy resources, research works improving energy efficiecy have been conducted world wide. Althogh NdFeB magnets usage have been expanded to various applications, key materials such as Nd and Dy, resouces lean heavily on specific area, China. Magnetic industry revently experienced skyrocketing price fluctuatioin of rare earth at around 2008. Chineses government's regulations worsened the situation and arose a necessity to develop methods to minimize rare earth use. In this presentation, POSCO's recent research works on rare earth reduction is presented including novel powder alloying method using nitrate precursors. Also, future R&D plans for rare earth free magnets is briefly introduced as well.

• Journal of Information Technology Applications and Management
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• v.21 no.3
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• pp.97-117
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• 2014

People can differently act online than in real-life. Their virtual identities may allow them to express themselves more freely. In this perspective, there is a self-discrepancy between virtual- and real-life. Due to the anonymity, people can feel free to express who actually they are online without considering social pressure. Especially, for those people who live in a repressed society, virtual-selves can play a significant role to achieve their well-being. For this reason, a self-discrepancy between actual- and virtual-self related to well-being was studied. With 183 survey responses, political freedom, extraversion and neuroticism are identified as significant influencers of subjective well-being (SWB). In addition, an increase in self-discrepancy between virtual- and real-life for 'unhappy' people leads to an increased online well-being, which is contradictory to Higgins' self-discrepancy theory.

• Speech Sciences
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• v.8 no.4
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• pp.157-168
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• 2001

The limited capacity model has been used to explain linguistic interactions and trade-offs that occur in children's speech. The purpose of the present investigation is to explore the interrelationship of MLU (as an index of syntactic development) and fluency in the spontaneous speech of normal children. Twenty normal children's (ten girls and ten boys, aged 36-48 months) spontaneous speech samples were obtained during free-play interactions with their mothers or other adults. The results indicated that the MLU of disfluent utterances were significantly longer than that of fluent utterances. Also, disfluencies occurred more frequently in longer utterances than in shorter utterances. In addition, the utterances where disfluencies occurred more than 2 times were longer than those where disfluencies occurred once. These results imply that the increase of MLU appear to affect not only the occurrence of disfluent utterances, but also the number of disfluencies within the utterances. In other' words, these findings show that there are trade-off effects between MLU and fluency. This is discussed within a limited capacity framework.

• Bulletin of the Korean Chemical Society
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• v.26 no.8
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• pp.1255-1259
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• 2005

Lewy bodies (LBs) are neuronal inclusions that are closely related to Parkinson's disease (PD). The filamentous component of LB from patients with PD contains biochemically altered $\alpha$-synuclein. We have investigated the effect of the oxidized products of catecholamines on the modification of $\alpha$-synuclein. When $\alpha$-synuclein was incubated with the oxidized 3,4-dihydroxyphenylalanine (L-DOPA) or dopamine, the protein was induced to be aggregated. The oxidized catecholamine-mediated $\alpha$-synuclein aggregation was enhanced by copper ion. Radical scavengers, azide and N-acetyl cysteine significantly prevented the oxidized catecholamine-mediated $\alpha$-synuclein aggregation. The results suggest that free radical may play a role in $\alpha$-synuclein aggregation. Exposure of $\alpha$-synuclein to the oxidized products of catecholamines led to the formation of dityrosine. Antioxidant dipeptides carnosine, homocarnosine and anserine significantly protected $\alpha$-synuclein from the aggregation induced by the oxidized products of catecholamines.