• The korean journal of orthodontics
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• v.36 no.5
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• pp.339-348
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• 2006

Objective: With development of the skeletal anchorage system, orthodontic mini-implant (OMI) assisted on masse sliding retraction has become part of general orthodontic treatment. But compared to the emphasis on successful anchorage preparation, the control of anterior teeth axis has not been emphasized enough. Methods: A 3-D finite element Base model of maxillary dental arch and a Lingual tipping model with lingually inclined anterior teeth were constructed. To evaluate factors influencing the axis of anterior teeth when OMI was used as anchorage, models were simulated with 2 mm or 5 mm retraction hooks and/or by the addition of 4 mm of compensating curve (CC) on the main archwire. The stress distribution on the roots and a 25000 times enlarged axis graph were evaluated. Results: Intrusive component of retraction force directed postero-superiorly from the 2 mm height hook did not reduce the lingual tipping of anterior teeth. When hook height was increased to 5 mm, lateral incisor showed crown-labial and root-lingual torque and uncontrolled tipping of the canine was increased.4 mm of CC added to the main archwire also induced crown-labial and root-lingual torque of the lateral incisor but uncontrolled tipping of the canine was decreased. Lingual tipping model showed very similar results compared with the Base model. Conclusion: The results of this study showed that height of the hook and compensating curve on the main archwire can influence the axis of anterior teeth. These data can be used as guidelines for clinical application.

• Asia pacific journal of information systems
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• v.21 no.4
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• pp.63-104
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• 2011

The study examines the relationships among employee's goal orientation, IT personnel competency, personal effectiveness. The goal orientation includes learning goal orientation, performance approach goal orientation, and performance avoid goal orientation. Personal effectiveness consists of personal work satisfaction and personal work performance. In general, IT personnel competency refers to IT expert's skills, expertise, and knowledge required to perform IT activities in organizations. However, due to the advent of the internet and the generalization of IT, IT personnel competency turns out to be an important competency of technological experts as well as employees in organizations. While the competency of IT itself is important, the appropriate harmony between IT personnel's business capability and technological capability enhances the value of human resources and thus provides organizations with sustainable competitive advantages. The rapid pace of organization change places increased pressure on employees to continually update their skills and adapt their behavior to new organizational realities. This challenge raises a number of important questions concerning organizational behavior? Why do some employees display remarkable flexibility in their behavioral responses to changes in the organization, whereas others firmly resist change or experience great stress when faced with the need to alter behavior? Why do some employees continually strive to improve themselves over their life span, whereas others are content to forge through life using the same basic knowledge and skills? Why do some employees throw themselves enthusiastically into challenging tasks, whereas others avoid challenging tasks? The goal orientation proposed by organizational psychology provides at least a partial answer to these questions. Goal orientations refer to stable personally characteristics fostered by "self-theories" about the nature and development of attributes (such as intelligence, personality, abilities, and skills) people have. Self-theories are one's beliefs and goal orientations are achievement motivation revealed in seeking goals in accordance with one's beliefs. The goal orientations include learning goal orientation, performance approach goal orientation, and performance avoid goal orientation. Specifically, a learning goal orientation refers to a preference to develop the self by acquiring new skills, mastering new situations, and improving one's competence. A performance approach goal orientation refers to a preference to demonstrate and validate the adequacy of one's competence by seeking favorable judgments and avoiding negative judgments. A performance avoid goal orientation refers to a preference to avoid the disproving of one's competence and to avoid negative judgements about it, while focusing on performance. And the study also examines the moderating role of work career of employees to investigate the difference in the relationship between IT personnel competency and personal effectiveness. The study analyzes the collected data using PASW 18.0 and and PLS(Partial Least Square). The study also uses PLS bootstrapping algorithm (sample size: 500) to test research hypotheses. The result shows that the influences of both a learning goal orientation (${\beta}$ = 0.301, t = 3.822, P < 0.000) and a performance approach goal orientation (${\beta}$ = 0.224, t = 2.710, P < 0.01) on IT personnel competency are positively significant, while the influence of a performance avoid goal orientation(${\beta}$ = -0.142, t = 2.398, p < 0.05) on IT personnel competency is negatively significant. The result indicates that employees differ in their psychological and behavioral responses according to the goal orientation of employees. The result also shows that the impact of a IT personnel competency on both personal work satisfaction(${\beta}$ = 0.395, t = 4.897, P < 0.000) and personal work performance(${\beta}$ = 0.575, t = 12.800, P < 0.000) is positively significant. And the impact of personal work satisfaction(${\beta}$ = 0.148, t = 2.432, p < 0.05) on personal work performance is positively significant. Finally, the impacts of control variables (gender, age, type of industry, position, work career) on the relationships between IT personnel competency and personal effectiveness(personal work satisfaction work performance) are partly significant. In addition, the study uses PLS algorithm to find out a GoF(global criterion of goodness of fit) of the exploratory research model which includes a mediating variable, IT personnel competency. The result of analysis shows that the value of GoF is 0.45 above GoFlarge(0.36). Therefore, the research model turns out be good. In addition, the study performs a Sobel Test to find out the statistical significance of the mediating variable, IT personnel competency, which is already turned out to have the mediating effect in the research model using PLS. The result of a Sobel Test shows that the values of Z are all significant statistically (above 1.96 and below -1.96) and indicates that IT personnel competency plays a mediating role in the research model. At the present day, most employees are universally afraid of organizational changes and resistant to them in organizations in which the acceptance and learning of a new information technology or information system is particularly required. The problem is due' to increasing a feeling of uneasiness and uncertainty in improving past practices in accordance with new organizational changes. It is not always possible for employees with positive attitudes to perform their works suitable to organizational goals. Therefore, organizations need to identify what kinds of goal-oriented minds employees have, motivate them to do self-directed learning, and provide them with organizational environment to enhance positive aspects in their works. Thus, the study provides researchers and practitioners with a matter of primary interest in goal orientation and IT personnel competency, of which they have been unaware until very recently. Some academic and practical implications and limitations arisen in the course of the research, and suggestions for future research directions are also discussed.

• Asia pacific journal of information systems
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• v.20 no.3
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• pp.167-190
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• 2010

The research conducted here focuses on the effect of factors that affect the behavior of UCC (User Created Content) website users, other than user's rational recognition of how useful a UCC website can be. Most discussions in the existing literature on information systems have focused on users' evaluation how a UCC website can help to attain the users' own goals. However, there are other factors and this research pays attention to an individual's 'personality,' which is stable and biological in nature. Specifically, I have noted here that 'extroversion' and 'neuroticism,' the two common personality factors presented in Eysenck's most representative 'EPQ Model' and 'Big Five Model,' are the two personality factors that affect a site's 'usefulness,' by this I mean how useful does the user consider the website and its content. How useful a site is considered by the user is the other factor that has been regarded as the antecedent factor that influences the adoption of information systems in the existing MIS (Management Information System) research. Secondly, as using or creating a UCC website does not guarantee the user's or the creator's extrinsic motivation, unlike when using the information system within an organization, there is a greater likelihood that the increase in user's activities in relation to a UCC website is motivated by emotional factors rather than rational factors. Thus, I have decided to include the relationship between an individual's personality and what they find pleasurable in the research model. Thirdly, when based on the S-O-R Paradigm of Mehrabian and Russell, the two cognitive factors and emotional factors are finally affected by stimulus, and thus these factors ultimately have an effect on an individual's respondent behavior. Therefore, this research has presented an assumption that the recognition of how useful the site and content is and what emotional pleasure it provides will finally affect the behavior of the UCC website users. Finally, the relationship between the recognition of how useful a site is and how pleasurable it is to useand UCC usage may differ depending on certain situational conditions. In other words, the relationship between the three factors may vary according to how much users are involved in the creation of the website content. Creation thus emerges as the keyword of UCC. I analyzed the above relationships through the moderating variable of the user's involvement in the creation of the site. The research result shows the following: When it comes to the relationship between an individual's personality and what they find pleasurable it is extroverted users who have a greater likelihood to feel pleasure when using a UCC website, as was expected in this research. This in turn leads to a more active usage of the UCC web site because a person who is an extrovert likes to spend time on activities with other people, is sensitive to new experiences and stimuli and thus actively responds to these. An extroverted person accepts new UCC activities as part of his/her social life, rather than getting away from this new UCC environment. This is represented by the term 'Foxonomy' where the users meet a variety of users from all over the world and contact new types of content created by these users. However, neuroticism creates the opposite situation to that created by extroversion. The representative symptoms of neuroticism are instability, stress, and tension. These dispositions are more closely related to stress caused by a new environment rather than this creatingcuriosity or pleasure. Thus, neurotic persons have an uneasy feeling and will eventually avoid the situation where their own or others' daily lives are frequently exposed to the open web environment, this eventually makes them have a negative attitude towards the web environment. When it comes to an individual's personality and how useful site is, the two personality factors of extroversion and neuroticism both have a positive relationship with the recognition of how useful the site and its content is. The positive, curious, and social dispositions of extroverted persons tend to make them consider the future usefulness and possibilities of a new type of information system, or website, based on their positive attitude, which has a significant influence on the recognition of how useful these UCC sites are. Neuroticism also favorably affects how useful a UCC website can be through a different mechanism from that of extroversion. As the neurotic persons tend to feel uneasy and have much doubt about a new type of information system, they actively explore its usefulness in order to relieve their uncomfortable feelings. In other words, neurotic persons seek out how useful a site can be in order to secure their own stable feelings. Meanwhile, extroverted persons explore how useful a site can be because of their positive attitude and curiosity. As a lot of MIS research has revealed that the recognition of how useful a site can be and how pleasurable it can be to use have been proven to have a significant effect on UCC activity. However, the relationship between these factors reveals different aspects based on the user's involvement in creation. This factor of creationgauges the interest of users in the creation of UCC contents. Involvement is a variable that shows the level of an individual's mental effort in creating UCC contents. When a user is highly involved in the creation process and makes an enormous effort to create UCC content (classed a part of a high-involvement group), their own pleasure and recognition of how useful the site is have a significantly higher effect on the future usage of the UCC contents, more significantly than the users who sit back and just retrieve the UCC content created by others. The cognitive and emotional response of those in the low-involvement group is unlikely to last long,even if they recognize the contents of a UCC website is pleasurable and useful to them. However, the high-involvement group tends to participate in the creation and the usage of UCC more favorably, connecting the experience with their own goals. In this respect, this research presents an answer to the question; why so many people are participating in the usage of UCC, the representative form of the Web 2.0 that has drastically involved more and more people in the creation of UCC, even if they cannot gain any monetary or social compensation. Neither information system nor a website can succeed unless it secures a certain level of user base. Moreover, it cannot be further developed when the reasons, or problems, for people's participation are not suitably explored, even if it has a certain user base. Thus, what is significant in this research is that it has studied users' respondent behavior based on an individual's innate personality, emotion, and cognitive interaction, unlike the existing research that has focused on 'compensation' to explain users' participation with the UCC website. There are also limitations in this research. Firstly, I divided an individual's personality into extroversion and neuroticism; however, there are many other personal factors such as neuro-psychiatricism, which also needs to be analyzed for its influence on UCC activities. Secondly, as a UCC website comes in many types such as multimedia, Wikis, and podcasting, these types need to be included as a sub-category of the UCC websites and their relationship with personality, emotion, cognition, and behavior also needs to be analyzed.

• Korean Journal of Occupational Health Nursing
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• v.7 no.1
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• pp.5-19
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• 1998

This descriptive-correlational study was conducted to identify the major factors affecting health promoting behaviors. 344 workers who employed in four different manutacturing plants in Taegu and Kyungbuk area were selected by convenience sampling method. Data were collected from April let to April 18th, 1998 by ready structured questionaires. The purpose of this study was to offer the basic data for health promotion theory development and health promotion strategy planning. This study was based on Pender's Health Promotion Model and examined three variables health promoting behavior, self-concept and perceived importance of health. The Life Style and Health Habit Assessment scale(LHHA) developed by Pender(1982).The Self-concept scale developed by Choi(1972) and the Health Value scale developed by Wallston, Maides and Wallston(1980) were used for this study. Data was analyzed by percentage, mean. t-test. ANOVA, Pearson Correlation Coefficient, and Stepwise Multiple Regression. The major findings of this study are as follows ; 1. The average level of health promoting behavior practice was 63.2% and possible range was from 62 to 248 point. The mean score of respondent's positive self-concept was 75.8. 81.4% of respondents put a high priority on the importance of health. 2. There was a significant difference between the practice level in the category of general self care and less amount of working hours per day(P=0.000), less amount of working hours per week(P=0.000). There was a significant difference between the practice level in the category of nutrition and age(0.002), marital status(0.000), working hour per day(0.008), working hours per week(0.001), There was a significant difference between the practice level in the category of nutriton and sex(0.000), age(0.000), marital status(0.025), education level(0.000), working hours per day(0.002), working hours per week(0.006). There was a significant difference between the practice level in the category of sleep and rest and age(0.003), marital status(0.002), working hours per day(0.001), working hours per week(0.001). There was a significant difference between the practice level in the category of stress management and working hours per day(0.001), working hours per week(0.002). There was a significant difference between the practice level in the category of self-actualization and working hours per day(0.050). 3. General characteristics influencing the respodent's self-concept were level(P=0.009) and worksite(P=0.001). 4. The results of the hypothesis tests are as follows The first hypothesis, that "The respondent who have more positive self-concept will have higher scores in the practice of health promoting behavior." was supported(r=0.2973, P=0.0001). The second hypothesis that "The respondent who have higher perception level on importance of health will have higher scores in the practice health promoting behavior." was rejected(r=- 0665, P=0.2225). 5. The most important factor that affects health promoting behavior practice was working hours per week(6.0%). The combination of working hours per week, age, education level accounted for 10.0% of the variance in health promoting behavior. In conclusion, the results of this study on industrial workers supported Pender's health promotion model in partial and showed the relatedness between self concept and the practice of health promoting behavior. Further research is required to find factors influencing health promoting behaviors of industrial workers.

• Journal of the Korean Academy of Child and Adolescent Psychiatry
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• v.15 no.1
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• pp.61-74
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• 2004

Objectives：This study was performed to introduce a psychoeducational family therapy model for the families of schizophrenic patient and to investigate the effect of this model on the changes in coping style and depressive symptoms of the family members, and in perception of emotional support by families and depressive symptoms of patients. Methods：Nine preschool children, 3-5 years old, experiencing physical injuries caused by attack from a psychotic patient at kindergarten, were evaluated for psychological assessments；Intelligence test, MSSB(MacArthur Story-Stem Battery), H-T-P test(House-Tree-Person test). And their parents completed rating scale, KPI-C(Korean Personality Inventory for Children about children’s psychological conditions). Results：With respects to the contents and emotional reactions of MSSB, 9 preschool children showed generally high levels of anxiety, depression, avoidance, aggression, probably related to the traumatic experiences. Even though children couldn't verbally report directly about their traumatic experiences, in both MSSB, structured play narrative assessment tool, and HPT, free drawing and association test, they demonstrated psychiatric problems through reenactment plays, regardless of clinical diagnoses. Conclusion：Present study allowed us the chance to see beyond the outer pathological behaviors of PTSD in preschool children, through deeper evaluations of their mental representation. These preliminary data suggest deep understanding of internal representation would be of help for thorough evaluations and treatment plan for preschool children, experiencing severe trauma.

• Proceedings of the Korean Society of Crop Science Conference
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• 2017.06a
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• pp.8-9
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• 2017

Soybean yield has been low and unstable in Japan and other areas in East Asia, despite long history of cultivation. This is contrasting with consistent increase of yield in North and South America. This presentation tries to describe perspective of breaking stagnation of soybean yield in East Asia, considering the factors of the different yields between regions. Large amount of rainfall with occasional dry-spell in the summer is a nature of monsoon climate and as frequently stated excess water is the factor of low and unstable soybean yield. For example, there exists a great deal of field-to-field variation in yield of 'Tanbaguro' soybean, which is reputed for high market value and thus cultivated intensively and this results in low average yield. According to our field survey, a major portion of yield variation occurs in early growth period. Soybean production on drained paddy fields is also vulnerable to drought stress after flowering. An analysis at the above study site demonstrated a substantial field-to-field variation of canopy transpiration activity in the mid-summer, but the variation of pod-set was not as large as that of early growth. As frequently mentioned by the contest winners of good practice farming, avoidance of excess water problem in the early growth period is of greatest importance. A series of technological development took place in Japan in crop management for stable crop establishment and growth, that includes seed-bed preparation with ridge and/or chisel ploughing, adjustment of seed moisture content, seed treatment with mancozeb+metalaxyl and the water table control system, FOEAS. A unique success is seen in the tidal swamp area in South Sumatra with the Saturated Soil Culture (SSC), which is for managing acidity problem of pyrite soils. In 2016, an average yield of $2.4tha^{-1}$ was recorded for a 450 ha area with SSC (Ghulamahdi 2017, personal communication). This is a sort of raised bed culture and thus the moisture condition is kept markedly stable during growth period. For genetic control, too, many attempts are on-going for better emergence and plant growth after emergence under excess water. There seems to exist two aspects of excess water resistance, one related to phytophthora resistance and the other with better growth under excess water. The improvement for the latter is particularly challenging and genomic approach is expected to be effectively utilized. The crop model simulation would estimate/evaluate the impact of environmental and genetic factors. But comprehensive crop models for soybean are mainly for cultivations on upland fields and crop response to excess water is not fully accounted for. A soybean model for production on drained paddy fields under monsoon climate is demanded to coordinate technological development under changing climate. We recently recognized that the yield potential of recent US cultivars is greater than that of Japanese cultivars and this also may be responsible for different yield trends. Cultivar comparisons proved that higher yields are associated with greater biomass production specifically during early seed filling, in which high and well sustained activity of leaf gas exchange is related. In fact, the leaf stomatal conductance is considered to have been improved during last a couple of decades in the USA through selections for high yield in several crop species. It is suspected that priority to product quality of soybean as food crop, especially large seed size in Japan, did not allow efficient improvement of productivity. We also recently found a substantial variation of yielding performance under an environment of Indonesia among divergent cultivars from tropical and temperate regions through in a part biomass productivity. Gas exchange activity again seems to be involved. Unlike in North America where transpiration adjustment is considered necessary to avoid terminal drought, under the monsoon climate with wet summer plants with higher activity of gas exchange than current level might be advantageous. In order to explore higher or better-adjusted canopy function, the methodological development is demanded for canopy-level evaluation of transpiration activity. The stagnation of soybean yield would be broken through controlling variable water environment and breeding efforts to improve the quality-oriented cultivars for stable and high yield.

• The Journal of Korean Academy of Prosthodontics
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• v.45 no.6
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• pp.753-759
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• 2007

Statement of problem. In distal extension removable partial denture, the preservation of health of abutment teeth is very important, but abutment teeth are subjected to unfavorable stress under unilateral loading specially. Purpose. The purpose of this study was to investigate the biomechanical effects of mandibular removable partial dentures with various prosthetic designs under unilateral loading, using strain gauge analysis. Material and methods. Artificial teeth of both canines were anchored bilaterally in a mandibular edentulous model made of resin. Bilateral distal extension removable partial dentures with splinted and unsplinted abutments were fabricated. Group 1: Clasp-retained mandibular removable partial denture with unsplinted abutments Group 2: Clasp-retained mandibular removable partial denture with splinted abutments by 6-unit bridge. Group 3: Bar-retained mandibular removable partial denture Strain gauges were bonded on the labial plate of the mandibular resin model, approximately 2 mm dose to the abutments. Two unilateral vertical experimental loadings (30N and 100N) were applied subsequently via miniature load cell that were placed at mandibular left first molar region. Strain measurements were performed and simultaneously monitored from a computer connected to data acquisition system. For within-group evaluations, t-test was used to compare the strain values and for between-group comparisons, a one-way analysis of variance (ANOVA) was used and Tukey test was used as post hoc comparisons. Results. The strain values of group 1 and 2 were tensile under loadings. In contrast, strain values of group 3 were compressive in nature. Strain values increased as the applied load in increased from 30N to 100N (p<.05) except for right side in group 1. Under 30N loading, in left side, group 1 showed higher strain values than groups 2 and 3 in absolute quantity (p<.05). And group 2 showed higher strain values than group 1 (p<.05). In right side, group 1 and 2 showed higher strain values than group 3 in absolute quantity (p<.05). Under 100N loading in left side, group 1 showed higher strain values than groups 2 and 3 in absolute quantity (p<.05). And group 2 showed higher strain values than group 1 (p<.05). In right side, group 1 and 2 showed higher strain values than group 3 in absolute quantity (p<.05). Under 30N loading, group 2 and 3 showed higher strain values in right side than in left side. Under 100N loading, right side strain values were higher than left side ones for all groups. Conclusion. Splinting of two isolated abutments by bridge reduced the peri-abutment strain in comparison with unsplinted abutments under unilateral loading. Bar-retained removable partial denture showed the lowest strain of three groups, and compressive nature.

• Journal of Korean Society of Forest Science
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• v.109 no.3
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• pp.259-270
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• 2020

Extreme weather events, such as heat and drought, have occurred frequently over the past two decades. This has led to continuous reports of cases of forest damage due to physiological stress, not pest damage. In 2014, pine trees were collectively damaged in the forest genetic resources reserve of Sogwang-ri, Uljin, South Korea. An investigation was launched to determine the causes of the dieback, so that a forest management plan could be prepared to deal with the current dieback, and to prevent future damage. This study aimedto 1) understand the topographic and structural characteristics of the area which experienced pine tree dieback, 2) identify the main causes of the dieback, and 3) predict future risk areas through the use of machine-learning techniques. A model for identifying risk areas was developed using 14 explanatory variables, including location, elevation, slope, and age class. When three machine-learning techniques-Decision Tree, Random Forest (RF), and Support Vector Machine (SVM) were applied to the model, RF and SVM showed higher predictability scores, with accuracies over 93%. Our analysis of the variable set showed that the topographical areas most vulnerable to pine dieback were those with high altitudes, high daily solar radiation, and limited water availability. We also found that, when it came to forest stand characteristics, pine trees with high vertical stand densities (5-15 m high) and higher age classes experienced a higher risk of dieback. The RF and SVM models predicted that 9.5% or 115 ha of the Geumgang Pine Forest are at high risk for pine dieback. Our study suggests the need for further investigation into the vulnerable areas of the Geumgang Pine Forest, and also for climate change adaptive forest management steps to protect those areas which remain undamaged.

• Journal of Korean Society of Rural Planning
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• v.20 no.4
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• pp.253-262
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• 2014

This, an association research for design-improvement and model-development of exhibition shops at rural tourism communities, is to secure objective data by analyzing customers' awareness-tendency of and demand for agricultural-specialty exhibition shops. Survey-questions for finding out consumers' awareness-tendency and demand were determined through brainstorming of a professional council, 30 rural communities of which visit-rate by consumers is considerably high were selected for the recruit of 200 consumers. For investigation and analysis, survey and in-depth interview were carried out at the scene with the application of frequency analysis and summarization of their opinions, which revealed that they have a strong will to visit the rural tourism communities for the purchase of agricultural specialties along with the experience of learning-program and on-the-scene direct dealing and that their viewpoint on the direct dealing at the scene was very positive. Also it was confirmed hat their satisfaction with the purchase of agricultural specialties by on-the-scene direct dealing, their pleasure at the purchase, their satisfaction with services and their intention for re-purchase of them were very high while their satisfaction with the exhibition shops was very low. With on-the-scene survey, the consumers' opinions could be listened to in depth. Almost all of them said their satisfaction with the trip to those rural tourism communities was considerably high since they could go to those communities themselves to relieve the stress from their modern life, to experience healing and to see the goods on the scene. Their satisfaction also was attributed to the fact that they have enough trust in purchase along with feeling the warm-heartedness of rural residents. As to their awareness of exhibition shops, they showed a positive response to the on-the-scene direct dealing at rural communities while they, thinking that the space in those exhibition shops was not sufficiently wide, demanded for more systematic counters in more accessible and affordable exhibition shops so that they might be more satisfied with the exhibition shops. Their demand for the necessity of exhibition shops selling agricultural specialties was found to be over 80%, which indicates that the necessity is very high. As to the suitability of function, they have the opinion that the business at those shops had better be focused on sales since they have the understanding of information when they take a trip to the rural communities, while there was another opinion: since agricultural products are seasonal items they should be exhibited and sold at the same time. More than 90% of the respondents had a positive viewpoint on direct dealing of agricultural specialties on the scene, which showed that their response to it was very high. They preferred the permanent shops equipped with roll-around table-booths. In addition, it was revealed that they want systematic exhibition shops in rural communities because they frequent those communities for on-the-scene direct purchase. The preferred type and opinion resulting from estimation of consumers' demands have been reflected for development of practical designs. The structure of variable principles has been designed so that the types of display-case and table-booth might be created. The result of this study is a positive data as a design model which can be utilized at rural communities and will be commercialized for the verification of its validity.

• Journal of Life Science
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• v.29 no.1
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• pp.9-17
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• 2019

As tumors develop, they encounter microenvironmental stress, such as hypoxia and glucose depletion, due to poor vascular function, thereby leading to necrosis, which is observed in solid tumors. Necrotic cells are known to release cellular cytoplasmic contents, such as high mobility group box 1 (HMGB1), into the extracellular space. The release of HMGB1, a proinflammatory and tumor-promoting cytokine, plays an important role in promoting inflammation and metabolism during tumor development. Recently, HMGB1 was shown to induce the epithelial-mesenchymal transition (EMT) and metastasis. However, the underlying mechanism of the HMGB1-induced EMT, invasion, and metastasis is unclear. In this study, we showed that noninvasive breast cancer cells MCF-7 formed tightly packed, rounded spheroids and that the cells in the inner regions of a multicellular tumor spheroid (MTS), an in vitro model of a solid tumor, led to necrosis due to an insufficient supply of O2 and glucose. In addition, after 7 d of MTS culture, the EMT was induced via the transcription factor Snail. We also showed that HMGB1 receptors, including RAGE, TLR2, and TLR4, were induced by MTS culture. RAGE, TLR2, and TLR4 shRNA inhibited MTS growth, supporting the idea that RAGE/TLR2/TLR4 play critical roles in MTS growth. They also prevented MTS culture-induced Snail expression, pointing to RAGE/TLR2/TLR4-dependent Snail expression. RAGE, TLR2, and TLR4 shRNA suppressed the MTS-induced EMT. In human cancer tissues, high levels of RAGE, TLR2, and TLR4 were detected. These findings demonstrated that the HMGB-RAGE/TLR2/TLR4-Snail axis played a crucial role in the growth of the MTS and MTS culture-induced EMT.