• Journal of Korean Society of Forest Science
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• v.104 no.4
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• pp.649-656
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• 2015

The objective of this study was to analyze the optimal thinning regimes for timber or carbon managements in Cryptomeria japonica stands of Hannam Experimental Forest, Korea Forest Research Institute. In solving the problem, PATH algorithm, developed by Paderes and Brodie, was used as the decision-making tool and the individual-tree/distance-free stand growth simulator for the species, developed by Kwon et al., was used to predict the stand growth associated with density control by thinning regimes and mortality. The results of this study indicate that the timber management for maximum net present value (NPV) needs less number of but higher intensity thinnings than the carbon management for maximum carbon absorption does. In case of carbon management, the amount of carbon absorption is bigger than that of timber management by about 6% but NPV is reduced by about 3.2%. On the other hand, intensive forest managements with thinning regimes promotes net income and carbon absorption by about 60% compared with those of the do-nothing option.

• The Journal of the Convergence on Culture Technology
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• v.6 no.2
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• pp.191-197
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• 2020

As an effective means of price discrimination, some suppliers offer trade credit to the distributors for the purpose of increasing the demand of the product they produce. The availability of the delay in payments from the supplier enables discount of the distributor's selling price from a wider range of the price option in anticipation of increased customer's demand. In this regard, we consider the problem of determining the distributor's optimal price and lot size simultaneously when the supplier permits delay in payments for an order of a product whose demand rate is represented by a constant price elasticity function. It is assumed that the distributor pays the shipping cost for the order and hence, the distributor's ordering cost consists of a fixed ordering cost and the shipping cost that depend on the order quantity. For the analysis, it is also assumed that inventory is depleted not only by customer's demand but also by decay. We are able to develop a solution algorithm from the properties of the mathematical model. A numerical example is presented to illustrate the algorithm developed.

• The Journal of Korea Assosiation for Disability and Oral Health
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• v.5 no.1
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• pp.12-17
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• 2009

Background : To do dental treatments successfully for dentally disabled patients who are unable to cooperate to procedures needs deep sedation (DS) or general anesthesia (GA). But there are some difficulties in selecting DS because of some disadvantages such as airway problem etc. But, if we select appropriate cases, DS would be better than GA. Methods : We reviewed total 238 cases of patients who had received dental treatments under GA or DS at the clinic for the disabled in Seoul National University Dental Hospital from November 2007 to February 2009. To compare anesthesia condition between DS and GA, we reviewed preanesthesia evaluation sheet, anesthesia or sedation records and PACU sheets retrospectively. Results : The number of DS cases was 25 (11%) and that of GA was 218 (89%). To maintain DS, intravenous propofol was infused with syringe pump (100%), and sevoflurane (134 cases) or propofol (13 cases) were used for sedation induction. Mean total treatment time for DS was 36 min and 2 hour 25 min for GA. The recovery time at PACU was 44 min for DS and 80 min for GA. There were no severe complications in DS, but 18 cases showed nausea and vomiting in GA. Conclusion : Deep sedation for disabled dental patients should be selected for effective behavioral control in conjunction with general anesthesia, considering duration and pain-evoking potentials of dental treatment and type and severity of patients' disabilities altogether.

• Journal of The Korean Association of Information Education
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• v.16 no.1
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• pp.131-142
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• 2012

In this paper, a support plan for marriage immigrants through e-learning was studied. Currently, the number of Korean men marrying foreign women is rapidly increasing due to the increase in the imbalance of gender ratios caused by preference for boys and shunning of rural areas by Korean women. To alleviate this problem, the government is performing various social adaptation programs such as Korean language education and vocational education. Most marriage immigrants, however, are not properly educated as they are burdened by their household duties or work. In this paper, a plan for supporting marriage immigrants through e-learning was researched. To achieve this goal, a survey on intentions of the marriage immigrants to receive muticultural education through e-learning was performed. The result showed that most of marriage immigrants have a strong preference for e-learning. However, there are differences on their preference depending on the original nationality and residential region. A support plan for multicultural education through e-learning was proposed according to the above result. The support plan consists of three parts. First, education for marriage immigrants will be specialized according to their respective original nationality. Second, Korean education will be given greater emphasis in education. Third, vocation education which will benefit marriage immigrants will be prepared. Above support plans are expected to help the marriage immigrants to settle as equal members of the society instead of deteriorating into an underprivileged class by providing them with an opportunity to receive education.

• Korean Business Review
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• v.19 no.2
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• pp.183-206
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• 2006

Recently, the notion of "increasing returns" has been popular not only in academia but also in industries. This notion has been drawn from prior research on network effects, which showed that the market evolution would lock in to a dominant technology. However, the long history of technological change has rarely shown the possibility of lock-in to an inferior technology. How could the market with network effects make transition between incompatible technologies regimes by escaping the lock-in? This paper analyzes the effectiveness of R&D and technological choice to investigate the sources of the dynamic capabilities in the presence of network effects and uncertain technological progress. Why does the market sometimes work against a radical technology, and why, at other times, does the market operate in favor of it? This study is to address this question by modeling the situation of two competing technologies in the presence of network effects. The numerical analysis indicates that the evolution strategy of compatibility is more likely to increase the chance of firm growth when a majority of customers are not power users or when demand for an old technology has been escalated. But when there are a substantial number of power users or when a new technology emerges before such an escalation of demand, the revolution strategy of compelling performance is more likely to be effective. The result suggests a potential mechanism for overcoming the lock-in problem. When the market exhibits some inertia to an obsolete technology, which is reinforced by the increasing customer value with respect to backward compatibility, the survival of a new technology depends on power users. When many power users are cultivated by firms' technological efforts regarding the new technology, the market is less likely to lock into an obsolete technology. Indeed, in the workstation market, where power users characterize much of the demand, innovators like Sun successfully switched to the RISC architecture.

• Journal of the Institute of Electronics Engineers of Korea SC
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• v.48 no.1
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• pp.47-54
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• 2011

The remote control mobile robot is the robot accomplishing a task according to the orders giving by a user through departed communication system using a joystick. Basically, to supply a lot of information, as this type of robot uses visual information, the user can check the transmitted information by eyes and give orders to the robot. But the weak point of this type of robot is that it has a possibility to come into a collision with an obstacle not be seen to the user because of the communication delay occurring in a communication system and dead zone happening in visual information. To solve the problem, in this paper, we try to suggest a system applying a fuzzy control system to the robot to avoid collision with an obstacle by an immediate order of the user. The fuzzy control system has better performance than any other existing control methods in the change of noise and parameter. And it is more efficient than any other since it solves easy the complexity of the system analysis occurring because of the nonlinear feature of the mobile robot system. In this paper, we made experiments how the mobile robot controlled by the fuzzy control system avoids an obstacle, tracks the path and avoids the obstacle in the path, to prove the performance and to check the evaluation and the application possibility of the fuzzy control system.

• Korean Journal of Veterinary Service
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• v.34 no.4
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• pp.341-352
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• 2011

Colibacillosis in pigs remain a major swine industry bruden worldwide. Although some progress has been made in treating collibacillosis in pigs by using biosecurity and antimicrobials, it still remain a considerable problem. The use of host-specific bateriophages as a biocontrol is one possible alternative. The purpose of this study was to evaluate the effect of bacteriophage against enterotoxigenic Escherichia coli (ETEC) K88 infection in piglets. Twenty-eight piglets were randomly divided into four groups and each group was allocated with 7 pigs. Group B, C and D were inoculated with 5 ml of ETEC K88 ($1{\times}10^8$ CFU/ml) per head of piglet via oral. Group C and D were fed with bacteriophages (Group C, $1.0{\times}10^6$ PFU/g; Group D, $1.0{\times}10^8$ PFU/g; CJ CheilJedang Corp., Korea) orally as treatment. In piglets administrated bacteriophages and challenged with ETEC K88 (Group C and D), Clinical signs and the growth performance were improved and antibody titers were maintained low level compared with piglets challenged with ETEC K88 (Group B, P<0.05). Group B were shown high pH in the alimentary tracts compared with other piglets (P<0.05). In quantitative analysis by real-time PCR, the results of Group C and D were lower than those Group B in faecal and intestinal samples (P<0.05). Severe villus atrophy and crypt hyperplasia were observed in Group B consequently V/C ratio increased, compared with other piglets. These results indicate that feeding with bacteriophage has effect to prevent ETEC K88 infection in piglets and suggest that use of bacteriophage can be considered a valid antibiotic alternative.

• Journal of Korea Water Resources Association
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• v.46 no.11
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• pp.1069-1078
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• 2013

The Bangudae Petroglyphs, national treasure No. 285 is located within submerged upper districts of Sayeon dam supplying the main residential water in Ulsan. Of the many ways for the reservation of Petroglyphs located the altitude at 53~57 m, the plan that we take it out of the water lowering the water level from 60 m to 52 m has been examined mainly in case of controlling artificially the water level of the dam. In this paper, we examined expected problems from the loss of dam function and the change of water quality from water deterioration caused by the water level control of the Sayeon dam. Using the model of Vollenweider and CSTR (Continuous Stirred Tank Reactor), we analyzed the density change of BOD and COD, representative water quality index and the TP and TN, the main reason of algae growth. The result showed that the density of COD lowered a little but the density of TP and TN went up over 130% when controlling the water level from 60 m to 52 m. These changes cause a serious algae problem and if doing the water quality management as the density of TN and TP, the water quality would become worse. Water storage and supply residential water decreases, and the water quality becomes worse because of eutrophic state.

• Physical Therapy Korea
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• v.27 no.1
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• pp.38-44
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• 2020

Background: Posterior shoulder tightness, which is a problem mainly seen in patients with shoulder impingement syndrome, disrupts the scapulohumeral rhythm between the humerus and scapulae. Objects: The aim of this study was to compare the effects of joint mobilization and stretching on shoulder muscle activity and internal rotation range of motion (ROM) of the glenohumeral joint in patients with impingement syndrome with posterior shoulder tightness. Methods: The research subjects included 22 in-patients with impingement syndrome with posterior shoulder tightness. They were randomly divided into two groups: one group (12 patients) was treated with joint mobilization and the other group (10 patients) was treated with stretching for the posterior shoulder tightness. Each treatment was performed five times a week for two weeks, and there were 15 sessions for each treatment. The ROM of the internal rotation and muscle activities of shoulder joint were evaluated pretest and posttest in each group. Electromyography data were collected from the upper, middle, and lower trapezius and serratus anterior during shoulder abduction of 90°, 120°, and 150°. Results: Both the joint mobilization and stretching groups showed significant decreases in muscle activity in the upper, middle, and lower trapezius on the posttest (p < 0.05). There was a significant difference in serratus anterior at 150° (p < 0.05), but there was no significant difference between group in post-hoc analysis (p > 0.025). The internal rotation ROM was significantly increased in the stretching group compared to that in the joint mobilization group (p < 0.025). Conclusion: This study found that both joint mobilization and stretching for posterior shoulder tightness were effective in muscle activity during arm abduction, also in order to increase internal rotation ROM of shoulder joint, stretching was effective in patients with impingement syndrome with posterior tightness.

• Journal of Korean Elementary Science Education
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• v.25 no.4
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• pp.363-373
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• 2006

The purposes of this study were to analyze the within-group verbal interactions in Thinking Science activities and compare the characteristics of verbal interactions shown by the pupils as well as the differences in help by e teacher in Korea with those in the UK. For the purposes of this study, 16 pupils from comparable groups by cognitive level were selected from both countries. Verbal interactions and teacher help during group discussions were audio/ video taped and the types of students' interactions were classified into interactions related to problem solving, management of classroom loaming and others. The results of this study showed that the verbal interactions in Korean groups were more activated than those in the UK groups. However, the percentages of high level interactions such as metacognitive questions, elaborative suggestions and logical argumentations were higher in the UK groups than those in the Korean groups. Observation of the within-group activities revealed that the pupils of both countries shared some common ground in the following ways; neither recognized the need to formulate the hypothesis in the process of inquiry and that the procedures of discussion were dominated by the pupils of higher cognitive level as the discussion proceeded. It was also observed that the pupils in the UK were considerate in response to the questions posed by both their peers or the teacher, while the pupils in Korea were influenced by their prior knowledge in the subject. Analysis of the teacher help during the inquiry activities showed that the tendency fur the teacher to emphasize the process rather than the product in the procedures of discussion and the extent he/she allowed the pupils to think and consider were closely related to the characteristics of the teacher himself/herself and was found to be a point of commonality in both countries. However, the teachers in the UK revealed the tendency of trying to propose the task to the pupils in concrete and systematic ways and guide the discussion based on the thinking of the pupils, while those in Korea tried to use strategies designed to draw out active verbal interactions among the pupils.