• Journal of Korea Water Resources Association
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• v.46 no.5
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• pp.449-463
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• 2013

This study proposes the method for determining the Muskingum channel routing model parameters based on the assumption of linear system. The proposed method was applied to the Chungju dam basin for the evaluation. Additionally, the rainfall-runoff was repeated for the Yeongchun-Chungju dam reach using seven rainfall events observed. Summarizing the results is as follows. First, the concentration time and storage coefficient of a channel reach formed by the subdivision can be expressed as the difference between the concentration times and storage coefficients of upstream and downstream basins. The storage coefficients of the channel reach estimated is equal to the storage coefficient of the Muskingum channel routing model and the weight factor can be simply estimated using the ratio between the concentration time and storage coefficient. Second, the weight factor of the Muskingum model is in inverse proportion to the Russel coefficient, which is in between 0.4166 and 0.625 when considering the Russel coefficients generally applied. Finally the application to the Yeongchun-Chungju dam reach showed that the proposed method is still valid regardless of the limitations such as the uncertainty of the observed data.

• Information Systems Review
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• v.24 no.4
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• pp.41-54
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• 2022

Despite the recent rapid advancement of science and technology, we have been experiencing the decline in productivity since the 2000s. This study aims to investigate the decline at both industry and firm levels, by looking at the emergence and growth of large firms such as Amazon, Alphabet, and Apple and M&A trends. Following the results of previous studies, our results show that productivity at industry level has decreased since the 2000s. Particularly, in the period after 2011, the deterioration of allocative efficiency due to the large firms and the decline in the growth rate of surviving firms in the industry with low ratio of large firms contributed to the productivity decline. On the other hand, our analysis at firm level demonstrates that the productivity of firms that acquired IT firms improved over the entire period. While M&As have a positive impact on productivity, M&As with a demand-side motive such as market penetration and expansion of channels have a relatively larger impact than the ones for production or operation efficiency. Our results also suggest that the higher the proportion of large firms in a specific industry, the lower the productivity of individual firms in the same industry. Overall, given that the industry's structural changes for digital transformation tends to strengthen the growth of large firms, our findings have significant implications by empirically identifying the relationships of the emergence of large firms, the acquisition of IT/Non-IT firms, and motivations for M&As to firm/industry productivity.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.25 no.6
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• pp.257-262
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• 2015

Recently the world wide efforts reduce occurrence of $CO_2$; global warming main reason. The aim of this study is to improve recycling rate of the fly ash (FA) and fused waste slag (FWS) from the power plant and to carbonate under supercritical condition ($40^{\circ}C$, $80kgf/cm^2$ pressure, 60 min) for $CO_2$ fixation. Specimens of mortar with various mixing ratios of FA, FWS (from 100:0 to 20:80 in 5 steps of 20 % reduction each time), distilled water and 3 M NaOH alkali activators were prepared. As a result, the proportion of weight change ratio increases with CaO content, to 12 % after carbonation under the supercritical condition. There is difference of compressive strength between the carbonated and the alkali activator mortar specimens. The stabilization of $CO_2$ fixation through carbonation which could confirm the applicability of the eco-friendly materials without loss of compressive strength.

• Journal of Korean Society of Forest Science
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• v.81 no.4
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• pp.325-336
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• 1992

The successional status and potential natural vegetation were examined in a mixed broadleaved-Abies forest located at Mt, Odae National Park. The examination was based on the subsequent process of generation replacement by understory saplings for the dominant canopy trees within 88 $5m{\times}50m$ belt transects. The transition matrix model, which was modified from mathematical theory of Markov chain, was employed to analyze the successional status of the study forest. The model suggests that the study forest is still seral, and it is considered to be more than 700 years away from the steady state or climax in terms of species composition. The simulations predict a remarkable decrease in the proportion of species composition of the present dominant Quercus mongolica and Tilia amurensi.s from current 28% and 13% to less than 3% and 5%, respectively, at the steady state. On the contrary, the proportions of Abies holophylla, Acer pseudo-sieboldianum, Carpinus cordata, and Pinus koraiensis will increase at the steady state. The ratio of mixture between deciduous and coniferous trees will be gradually changed from current 6.5 : 3.5 to 5.0 : 5.0 at equilibrium. Discussion for the problems of Quercus mongolica in successional status noted that the species behaved as a mid-successional dominant, not a climax species in the study forest. The hypothesis and sensitivity of the transition matrix model were also discussed to evaluate the applicability to the real situation. The overall results indicated that the present dynamics of the forest must reflect the seral state due to previous disturbance mainly by hyman related interference.

• Journal of Embryo Transfer
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• v.26 no.4
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• pp.277-282
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• 2011

The present research was carried out to evaluate the possibility of increasing female offspring production ratios using artificial insemination buffer (AIB) before artificial insemination (AI). In this experiment, we optimized AIB composition, made an AIB gun and analyze factors affecting AI non-return rate after AIB treatment. The AIB was made with the base of Tris-buffer supplemented with L-arginine and several other chemicals that might reduce the motility of male sperm compared to the female counterpart, therefore, increasing the possibility of fertilization by female sperm. AIB must be deposited into $2^{nd}$ to $4^{th}$ cervix by AIB gun. After 15 min of AIB deposition, frozen semen was deposited into the same place. A total of 348 cattle were inseminated with AIB insemination, and there were no significant differences between AIB and traditional AI non-return rates (56.8% vs. 55.7%). The AI non-return rate in AIB group, however, differed significantly among 7 Hanwoo farms. The parturition numbers ($1^{st}$ to $7^{th}$) of cows did not affect AIB AI rate. The proportion of AIB AI success rates was significantly higher in Hanwoo cows than in dairy cows (61.0% vs. 48.7%), but the average AI success rate did not differ significantly between AIB and conventional AI (56.8% vs. 55.7%). The female offspring production rate in $2^{nd}$ to $4^{th}$ cervix deposition place was significantly higher than that in the uterus body (77.7% vs. 59.6%, p<0.05). The injection volume of AIB in 5 and 10 ml was significantly higher than that in 2 ml (77.7%, 78.7% vs. 51.8%, p<0.05), but there were no differences in AIB injection volume between 5 and 10 ml. The best exposure time of AIB in the cervix was 10 to 15 min rather than 5 min (79.2%, 77.2% vs. 52.6%, p<0.05). AIB therefore needs to have an exposure time of at least over 10 min for a higher production rate of female offspring. In conclusion, AIB could be used in AI industry to increase the female offspring ratio and AIB AI can increase the AI success rate.

• Journal of the Korean Recycled Construction Resources Institute
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• v.5 no.2
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• pp.105-115
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• 2010

In this study, as one of solutions associated with the shortage of treatment area of industrial waste and the containment of its harmful components, the bottom ash which is known to be by-products of thermoelectric power plant was selected and its applicability for aggregate of concrete mixture was measured. Hardness test, sieve analysis, water-absorption test and SEM analysis were carried out to investigate the possibility of using bottom ash as a replacement of coarse and fine aggregate. Chemical analyses such as ignition loss test and X-ray incidence were carried out also. In addition, values for slump, strength, permeability, freeze and thaw, and carbonation were evaluated in terms of effects of replacement ratio of bottom ash. As the results, it was found that, though bottom ash is in short supply of fine particles and is in lack of cohesion, these problems can be solved by partially mixing with natural aggregates or improving in a process of production. In addition, bottom ash has not only advantage of durability but also acquirement of general compressive strengths in case that a certain proportion of natural aggregate is applied to mixture, in spite that unit water or chemical admixture should be increased to acquire good workability due to plenty of porosity.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.21 no.11
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• pp.833-842
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• 2020

The purpose of this study is to analyze the economic feasibility of technology developed by the National Institute of Animal Science used to shorten the raising term of Hanwoo cattle. This technology can address the increasing proportion of feed cost to operating expenses in the industry. The technology maintains quality by high nutrition breeding during the growing period while shortening the fattening period compared to conventional methods for castrated cattle. Our analysis employs the partial budget method, and results are as follows. First, we found that the ratio of shipment in age of less than 29 months has been increasing. Second, the statistical test finds that both the reduction in age of the months for shipment and the increase in dressed weight annually are significant. Third, the benefit of introducing the technology with the self-manufactured TMR accounts for 467,990 won per head/time. This result is strong evidence for prioritizing and extending pilot projects. In order to further expand this technology in the future, problems, limitations, and obstacles to introduction should be additionally disclosed for participating and non-participating farms after conducting the pilot project.

• Clinical and Experimental Pediatrics
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• v.49 no.8
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• pp.839-844
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• 2006

Purpose : We studied clinical patterns of the febrile infants and children presenting to the Pediatric Emergency Department(ED) in the general pediatric population. Method : We analyzed 1,764 infants and children who had a history of measured body temperature of $38.3^{\circ}C$ or higher, before or after arrival at Pediatric ED of Ilsan Paik Hospital from September 2004 to August 2005. We analyzed their clinical patterns, such as the frequency of febrile illness, age distribution, monthly distribution, diagnosis. Result : The frequency of the febrile illness at Pediatirc ED was 19.9 percent (1,764/8,881 cases). The percentage of admission into hospital was 26.4 percent. The most common age group presenting to Pediatric ED with febrile illness was the 12-23 months group(22.8 percent) followed by the 4-11 months group and the 2 years group. In May, the most numerous patients presented to the Pediatric ED with febrile illness. The frequency of febrile illness was significant higher in the 'Spring & Summer group' compared to the 'Autumn & Winter group'. The ratio of male to femal was 1.4:1. The most common diagnosis was acute pharyngitis(42.5 percent), followed by acute gastroenteritis (15.3 percent), pneumonia(7.0 percent). Conclusion : The frequency of the febrile illness at Pediatirc ED was 19.9 percent. The most numerous patients visited Pediatric ED in May. And, the most common age group was 12-23 months. The proportion of non-urgent disease, such as acute pharyngitis, acute gastroenteritis, acute nasopharyngitis and acute bronchitis, was high. There is a need to educate parents and improve the medical system in Korea.

• Journal of Yeungnam Medical Science
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• v.34 no.2
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• pp.191-199
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• 2017

Background: This study was conducted to provide a comparison between the clinical outcomes of primary percutaneous coronary intervention (PCI) and that of fibrinolysis followed by routine invasive treatment in ST elevation myocardial infarction (STEMI). Methods: A total of 184 consecutive STEMI patients who underwent primary PCI or fibrinolysis followed by a routine invasive therapy were enrolled from 2004 to 2011, and their major adverse cardiovascular events (MACEs) were compared. Results: Among the 184 patients, 146 patients received primary PCI and 38 patients received fibrinolysis. The baseline clinical characteristics were similar between both groups, except for triglyceride level ($68.1{\pm}66.62$ vs. $141.6{\pm}154.3mg/dL$, p=0.007) and high density lipoprotein level ($44.6{\pm}10.3$ vs. $39.5{\pm}8.1mg/dL$, p=0.005). The initial creatine kinase-MB level was higher in the primary PCI group ($71.5{\pm}114.2$ vs. $35.9{\pm}59.9ng/mL$, p=0.010). The proportion of pre-thrombolysis in MI 0 to 2 flow lesions (92.9% vs. 73.0%, p<0.001) was higher and glycoprotein IIb/IIIa inhibitors were administered more frequently in the primary PCI group. There was no difference in the 12-month clinical outcomes, including all-cause mortality (9.9% vs. 8.8%, p=0.896), cardiac death (7.8% vs. 5.9%, p=0.845), non-fatal MI (1.4% vs. 2.9%, p=0.539), target lesion revascularization (5.7% vs. 2.9%, p=0.517), and stroke (0% vs. 0%). The MACEs free survival rate was similar for both groups (odds ratio, 0.792; 95% confidence interval, 0.317-1.980; p=0.618). The clinical outcome of thrombolysis was not inferior, even when compared with primary PCI performed within 90 minutes. Conclusion: Early fibrinolysis with optimal antiplatelet and antithrombotic therapy followed by appropriate invasive procedure would be a comparable alternative to treatment of MI, especially in cases of shorter-symptom-to-door time.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.7 no.4
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• pp.209-214
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• 1974

The utilization dietary protein in young rainbow trout was investigated when feeded with the diets of controlled levels of casein and lipids for 12 days. The composition of the diet is shown in Table 1. Body weight gain was in proportion to the protein content in diet up to $40\%$, ana the maximum was obtained with $40.4\%$ of crude protein (Fig. 1, Table 2). On the other hand, the accumulated protein in body also showed almost maximum value around 40n of protein level in the diet and: the change of accumulated protein showed a little with more-protein level(Fig. 3, Table 9). The protein accumulation rate (protein accumulated/protein consumed) showed its highest value at about $40\%$ of protein level, while the protein utilization value (protein accumulation rate x protein content of diet) attained its highest value at $54.8\%$ of protein level (Table 3). With the above results it is observed that the requirement of dietary protein for young rainbow trout is about $40\%$ of protein in the diet when casein is used as the sole protein source. In protein efficiency ratio (PER) the lower protein level in the diet, the higher PER yields and the more the quantity of protein increases, the more PER decreases and its relation could be figured out as an equation of y=4.91-0.034x (Fig.4), Nose measured PER utilizing the diet which result of this, it is reported that PER rate of casein dropped within the extent of $25\%$ protein in diet. The reason why such a different PER rate appeared at the low protein level is revealed as the carbohydrate is low but the lipid high in capacity of utililzing nutrients for rainbow trout. The relation between the protein content of diet and the conversion factor, feed efficiency were determined and the results are shown in Fig. 2.