• Journal of the Korea Concrete Institute
• /
• v.25 no.5
• /
• pp.485-496
• /
• 2013

In recent years, frequent terror or military attacks by explosion or impact accidents have occurred. Examplary case of these attacks were World Trade Center collapse and US Department of Defense Pentagon attack on Sept. 11 of 2001. These attacks of the civil infrastructure have induced numerous casualties and property damage, which raised public concerns and anxiety of potential terrorist attacks. However, a existing design procedure for civil infrastructures do not consider a protective design for extreme loading scenario. Also, the extreme loading researches of prestressed concrete (PSC) member, which widely used for nuclear containment vessel, gas tank, bridges, and tunnel, are insufficient due to experimental limitations of loading characteristics. To protect concrete structures against extreme loading such as explosion and impact with high strain rate, understanding of the effect, characteristic, and propagation mechanism of extreme loadings on structures is needed. Therefore, in this paper, to evaluate the impact resistance capacity and its protective performance of bi-directional unbonded prestressed concrete member, impact tests were carried out on $1400mm{\times}1000mm{\times}300mm$ for reinforced concrete (RC), prestressed concrete without rebar (PS), prestressed concrete with rebar (PSR, general PSC) specimens. According to test site conditions, impact tests were performed with 14 kN impactor with drop height of 10 m, 5 m, 4 m for preliminary tests and 3.5 m for main tests. Also, in this study, the procedure, layout, and measurement system of impact tests were established. The impact resistance capacity was measured using crack patterns, damage rates, measuring value such as displacement, acceleration, and residual structural strength. The results can be used as basic research references for related research areas, which include protective design and impact numerical simulation under impact loading.

• KDI Journal of Economic Policy
• /
• v.13 no.4
• /
• pp.3-30
• /
• 1991

This paper examines Korea's exports of manufactures to the United States, Japan, and other OECD member countries in the 1974-89 period, focusing on the market share in the trade partners' imports. It decomposes the growth of exports into various effects, following the "constant-market-shares" analysis. For this purpose, the entire period is divided into three subperiods: 1974-78, 1978-83, and 1983-89. The paper also estimates a regression model of the market share determination, using the data of Korea's market share in U.S. imports. In the three subperiods under study, Korea's exports grew at different paces for varied reasons. The average annual growth rate was 28 %, 11 %, and 21 %, respectively. A large drop in the "competitiveness effect", that is, in the market-share growth rate, was mainly responsible for the decline in the export growth rate. The largest drop in the competitiveness effect was found in the light manufactures exports in the second period. The market share did not regain the rapid growth momentum. The main reason for the rise in export growth rate in the last subperiod was the "market-size effect"-a rise in the growth rate of the trade partners' imports. According to the regression results, high intensities in physical and human capital tended to lower the Korean manufacturing industries' market shares in the United States. This negative correlation was stronger in the case of human capital intensity, suggesting that Korea is relatively poorer in human capital endowment than in physical capital endowment when compared to the United States. This negative correlation between the market share and each of the two intensities became weaker overtime. This may be interpreted as the consequence of both physical and human capital accumulation which were faster than the labor force growth. Depreciation of the Japanese yen was estimated to have a negative influence on the Korean manufacturing industries' market share in the United States, and this negative influence became stronger each year in the 1980s. This seems to reflect the intensifying competition between the two countries' exports in U.S. import markets. The Heavy and Chemical Industry Policy of the 1970s, which promoted a number of selected industries by providing them with various incentives and inevitably discriminated against the rest of the industries, was estimated to have had strong negative effects on the export performance of the light manufacturing industries. This finding and the largest decline in the "competitiveness effect" -found in the light manufactures exports in the 1978-83 period-indicate that the Heavy and Chemical Industry Policy was mainly accountable for the drop in the export growth rate during the period. On the other hand, the rise in export growth rate during the subsequent subperiod was greatly impacted by the large scale exchange rate realignments of major currencies, especially by the appreciation of the Japanese yen, and other changes in international economic conditions.

• Journal of the Institute of Electronics Engineers of Korea TC
• /
• v.49 no.1
• /
• pp.31-46
• /
• 2012

The most critical technology to implement ubiquitous health care is Ubiquitous Sensor Network (USN) technology which makes use of various sensor technologies, processor integration technology, and wireless network technology-Radio Frequency Identification (RFID) and Wireless Sensor Network (WSN)-to easily gather and monitor actual physical environment information from a remote site. With the feature, the USN technology can make the information technology of the existing virtual space expanded to actual environments. However, although the RFID and the WSN have technical similarities and mutual effects, they have been recognized to be studied separately, and sufficient studies have not been conducted on the technical integration of the RFID and the WSN. Therefore, EPCglobal which realized the issue proposed the EPC Sensor Network to efficiently integrate and interoperate the RFID and WSN technologies based on the international standard EPCglobal network. The proposed EPC Sensor Network technology uses the Complex Event Processing method in the middleware to integrate data occurring through the RFID and the WSN in a single environment and to interoperate the events based on the EPCglobal network. However, as the EPC Sensor Network technology continuously performs its operation even in the case that the minimum conditions are not to be met to find complex events in the middleware, its operation cost rises. Moreover, since the technology is based on the EPCglobal network, it can neither perform its operation only for the sake of sensor data, nor connect or interoperate with each information system in which the most important information in the ubiquitous computing environment is saved. Therefore, to address the problems of the existing system, we proposed the design and implementation of USN integration management system. For this, we first proposed an integration system that manages RFID and WSN data based on Session Initiation Protocol (SIP). Secondly, we defined the minimum conditions of the complex events to detect unnecessary complex events in the middleware, and proposed an algorithm that can extract complex events only when the minimum conditions are to be met. To evaluate the performance of the proposed methods we implemented SIP-based integration management system.

• Journal of Environmental Science International
• /
• v.23 no.12
• /
• pp.2045-2056
• /
• 2014

In this study, pressure drop was measured in the pulse jet bag filter without venturi on which 16 numbers of filter bags (Ø$140{\times}850{\ell}$) are installed according to operation condition(filtration velocity, inlet dust concentration, pulse pressure, and pulse interval) using coke dust from steel mill. The obtained 180 pressure drop test data were used to predict pressure drop with multiple regression model so that pressure drop data can be used for effective operation condition and as basic data for economical design. The prediction results showed that when filtration velocity was increased by 1%, pressure drop was increased by 2.2% which indicated that filtration velocity among operation condition was attributed on the pressure drop the most. Pressure was dropped by 1.53% when pulse pressure was increased by 1% which also confirmed that pulse pressure was the major factor affecting on the pressure drop next to filtration velocity. Meanwhile, pressure drops were found increased by 0.3% and 0.37%, respectively when inlet dust concentration and pulse interval were increased by 1% implying that the effects of inlet dust concentration and pulse interval were less as compared with those changes of filtration velocity and pulse pressure. Therefore, the larger effect on the pressure drop the pulse jet bag filter was found in the order of filtration velocity($V_f$), pulse pressure($P_p$), inlet dust concentration($C_i$), pulse interval($P_i$). Also, the prediction result of filtration velocity, inlet dust concentration, pulse pressure, and pulse interval which showed the largest effect on the pressure drop indicated that stable operation can be executed with filtration velocity less than 1.5 m/min and inlet dust concentration less than $4g/m^3$. However, it was regarded that pulse pressure and pulse interval need to be adjusted when inlet dust concentration is higher than $4g/m^3$. When filtration velocity and pulse pressure were examined, operation was possible regardless of changes in pulse pressure if filtration velocity was at 1.5 m/min. If filtration velocity was increased to 2 m/min. operation would be possible only when pulse pressure was set at higher than $5.8kgf/cm^2$. Also, the prediction result of pressure drop with filtration velocity and pulse interval showed that operation with pulse interval less than 50 sec. should be carried out under filtration velocity at 1.5 m/min. While, pulse interval should be set at lower than 11 sec. if filtration velocity was set at 2 m/min. Under the conditions of filtration velocity lower than 1 m/min and high pulse pressure higher than $7kgf/cm^2$, though pressure drop would be less, in this case, economic feasibility would be low due to increased in installation and operation cost since scale of dust collection equipment becomes larger and life of filtration bag becomes shortened due to high pulse pressure.

• The Journal of Korean Academy of Prosthodontics
• /
• v.56 no.3
• /
• pp.179-187
• /
• 2018

Purpose: The purpose of this study was to investigate the effect of heat applied to disintegrate cement on the removal torque value and fracture strength of titanium abutment and abutment screw. Materials and methods: Implants, titanium abutments and abutment screws were prepared for each 20 piece. Implant abutments and screws were classified as the control group in which no heat was applied and the experimental group was heated in a vacuum furnace to $450^{\circ}C$ for 8 minutes and cooled in air. The abutments and screws were connected to the implants with 30 Ncm tightening torque at interval 10 minutes and the removal torque value was measured 15 minutes later. And the fracture strength of abutment screw was measured using universal testing machine. Results: The mean removal torque value was $27.84{\pm}1.07Ncm$ in the control group and $26.55{\pm}1.56Ncm$ in the experimental group and showed statistically significant difference (P < .05). The mean fracture strength was $731.47{\pm}39.46N$ in the control group and $768.58{\pm}46.73N$ in the experimental group and showed statistically no significant difference (P > .05). Conclusion: The heat applied for cement disintegration significantly reduced the removal torque value of the abutment screw and did not significantly affect fracture strength of the abutment screw. Therefore, in the case of applying heat to disintegrate cement it is necessary to separate the abutment screw or pay attention to the reuse of the heated screw. However further studies are needed to evaluate the clinical reuse of the heated screw.

• Journal of the korean academy of Pediatric Dentistry
• /
• v.29 no.4
• /
• pp.539-554
• /
• 2002

To identify the trend of pediatric dentistry in USA and Japan, closely related to Korean pediatric dentistry. The Japanese Journal of Pediatric Dentistry(JJPD) and The Journal of the American Academy of Pediatric Dentistry(PD) were reviewed. We collected the bibliographical data of the articles published in the two journals from 1991 to 2000. We analyzed thematic distributions and chronological changes, and then compare those of two groups. The following results were obtained: 1. The 869 articles were published in JJPD and 672 in PD. This was about 30% more in JJPD. 2. In both JJPD and PD, the case reports were a quarter of scientific articles in quantity. 3. The studies on the systemic diseases had the highest proportion in both JJPD and PD. The studies on the dental caries and restorative materials also had high proportion in both journals. 4. The studies on the sedation and biochemical survey had high proportion in PD when had low proportion in JJPD. To the contrary, The studies on the behavior science in JJPD were about double of those in PD. 5. There was no statistically significant difference in quantity between JJPD and PD in the studies on the dental caries, prevention of dental caries, community dental survey, conservative treatment, restorative materials, pulp treatment, diagnosis and treatment of malocclusion, oral pathology and minor surgery, local anesthesia and nerve tissue, traumatic injuries. 6. There was statistically significant increase in the studies on the dental equipment in JJPD and in those on restorative materials in PD. 7. There was statistically significant decrease in the studies on the prevention of dental caries and local anesthesia and nerve tissue in JJPD, and those on conservative treatment in PD.

• Journal of the korean academy of Pediatric Dentistry
• /
• v.40 no.4
• /
• pp.241-246
• /
• 2013

The purpose of this study was to investigate the synergistic effects of erythrosine sensitized with a conventional halogen curing unit and sub-minimal bactericidal concentration(sub-MBC) of chorhexidine on bacterial viability of Streptococcus mutans in planktonic state. Sub-minimal bactericidal concentration of chlorhexidine was added into wells containing bacteria and erythrosine. The range of concentrations tested for chorhexidine was from 0.0000001% to 0.001%. The irradiation of the bacterial suspensions was performed for 15 sec with a conventional halogen curing unit light. In another set of experiment, the effects of 0.001% chlorhexidine were observed by adding chlorhexidine into wells containing the sub-minimal bactericidal concentration of erythrosine. At the concetration of 0.001% chlorhexidine, there were no antibacterial effects in the absence of erythrosine PDT(p < 0.05). At the concentraton of $1{\mu}M$ erythrosine, there was no photodynamic therapy effect in the absence of chlorhexidine(p < 0.05). But in the presence of sub-minimal bactericidal concentration of erythrosine with light exposure, the addition of 0.001% chlorhexidine increased the bactericidal rate(p < 0.05). A combination of erythrosine PDT with sub-MBC chlorhexidine resulted in a significant reduction in bacterial counts when compared to the case with the absence of chlorhexidine.

• Culinary science and hospitality research
• /
• v.20 no.4
• /
• pp.169-182
• /
• 2014

This study investigates the physicochemical quality characteristics of tomato sauce added with different kinds of pimpinella brachycarpa. The results are as follows. The pH of tomato sauce added with freeze-dried pimpinella brachycarpa, in contrast to the tomato sauce with raw pimpinella brachycarpa, decreased as the addition quantity of the sample increased. As for sugar content, PBP0 with Pimpinella brachycarpa contained was shown to be the highest with 10.83. For chromaticity, all values (e.g, L, A and B) of tomato sauce added with pimpinella brachycarpa and with freeze-dried pimpinella brachycarpa decreased showing significant differences among the samples as the addition quantity of the samples increased. With increased addition quantity of the sample with freeze-dried Pimpinella brachycarpa, its water content decreased. PBP4, addition group with 4% of freeze-dried Pimpinella brachycarpa, was shown to be the highest DPPH free radical scavenging activity as 29.58. When adding Pimpinella brachycarpa to tomato sauce, a total number of micro-organisms decreased. In case of adding raw Pimpinella brachycarpa rather than freeze-dried Pimpinella brachycarpa, it created a further effect on an inhibitive action of growing and developing micro-organisms. In the preference of tomato sauce with Pimpinella brachycarpa, PBF2 with 2% of Pimpinella brachycarpa had the highest score as 5.1 for the color. For taste, 3.7, the lowest taste score, was shown in PBF1with 1% of Pimpinella brachycarpa. The overall preference revealed that PBF2 was the highest scoring 5.8.. PBF3 was scored highest with 5.9 for overall preference. From the comprehensive findings, 2~3% of the addition ratio between raw Pimpinella brachycarpa and freeze-dried Pimpinella brachycarpa in the production of tomato sauce is considered the most preferable.

• Journal of Intelligence and Information Systems
• /
• v.23 no.4
• /
• pp.1-31
• /
• 2017

Modern businesses are adopting new technologies to serve their markets better as well as to improve efficiency and productivity. The advertising industry has continuously experienced disruptions from the traditional channels (radio, television and print media) to new complex ones including internet, social media and mobile-based advertising. This case study focuses on proposing intelligent advertising business model in Seoul's metro network. Seoul has one of the world's busiest metro network and transports a huge number of travelers on a daily basis. The high number of travelers coupled with a well-planned metro network creates a platform where marketers can initiate engagement and interact with both customers and potential customers. In the current advertising model, advertising is on illuminated and framed posters in the stations and in-car, non-illuminated posters, and digital screens that show scheduled arrivals and departures of metros. Some stations have digital screens that show adverts but they do not have location capability. Most of the current advertising media have one key limitation: space. For posters whether illuminated or not, one space can host only one advert at a time. Empirical literatures show that there is room for improving this advertising model and eliminate the space limitation by replacing the poster adverts with digital advertising platform. This new model will not only be digital, but will also provide intelligent advertising platform that is driven by data. The digital platform will incorporate location sensing, e-commerce, and mobile platform to create new value to all stakeholders. Travel cards used in the metro will be registered and the card scanners will have a capability to capture traveler's data when travelers tap their cards. This data once analyzed will make it possible to identify different customer groups. Advertisers and marketers will then be able to target specific customer groups, customize adverts based on the targeted consumer group, and offer a wide variety of advertising formats. Format includes video, cinemagraphs, moving pictures, and animation. Different advert formats create different emotions in the customer's mind and the goal should be to use format or combination of formats that arouse the expected emotion and lead to an engagement. Combination of different formats will be more effective and this can only work in a digital platform. Adverts will be location based, ensuring that adverts will show more frequently when the metro is near the premises of an advertiser. The advertising platform will automatically detect the next station and screens inside the metro will prioritize adverts in the station where the metro will be stopping. In the mobile platform, customers who opt to receive notifications will receive them when they approach the business premises of advertiser. The mobile platform will have indoor navigation for the underground shopping malls that will allow customers to search for facilities within the mall, products they may want to buy as well as deals going on in the underground mall. To create an end-to-end solution, the mobile solution will have a capability to allow customers purchase products through their phones, get coupons for deals, and review products and shops where they have bought a product. The indoor navigation will host intelligent mobile-based advertisement and a recommendation system. The indoor navigation will have adverts such that when a customer is searching for information, the recommendation system shows adverts that are near the place traveler is searching or in the direction that the traveler is moving. These adverts will be linked to the e-commerce platform such that if a customer clicks on an advert, it leads them to the product description page. The whole system will have multi-language as well as text-to-speech capability such that both locals and tourists have no language barrier. The implications of implementing this model are varied including support for small and medium businesses operating in the underground malls, improved customer experience, new job opportunities, additional revenue to business model operator, and flexibility in advertising. The new value created will benefit all the stakeholders.

• Journal of Korean Society of Forest Science
• /
• v.96 no.3
• /
• pp.307-316
• /
• 2007

Yellow poplar (Liriodendron tulipifera L.) has low germination rate relatively other species, so the seedling production of Yellow poplar is a hard task. Accordingly this study was conducted to determine the optimal germination conditions for healthy seedling production and to promote survival rate after afforestation. Gemination percentage was examined at different media and seed covering materials using planting flats in the greenhouse. The best germination percentage was observed in sand for media and compound soil for covering materials. But it was time to transplant, seedlings became a poor character (i.e. height, root length, number of root, dry weight) in sand for media. In order to produce healthy seedlings, each different medium was compounded with TKS-2 (this is a gardening bed soil.) in the ratio 1:1 (v/v.), and compared two conditions. Quality of seedling was better than not mixed TKS-2 into each medium. Transplanting seedlings from greenhouse to nursery grew up rapidly 2 months later (early in August~early in October). Growth amount during two months corresponded to 85.6% and 71.3% in total growth amount of height and diameter at root collar, respectively. In the case of the competition-density effect on yellow-poplar seedlings, direct seedling produced the maximum 35 standard seedlings above 8 mm of root collar diameter per $m^2$, while transplanting seedling produced the maximum 64 standard seedlings per $m^2$. And produced seedlings of two way were significantly different rootlet while axial root and lateral root was not significantly different.