• Korean Journal of Ecology and Environment
• /
• v.34 no.4 s.96
• /
• pp.310-318
• /
• 2001

In the large regulated Nakdong River, the Predation effect of juvenile fish on the zooplankton community was evaluated by gut and stomach analyses of fish in 1999. Juvenile fish of five species showed high density from May to early June when river discharge was low and water body became stagnant. During this period, large rotifers, Asplanchna spp. and Brachionus spp. declined and the decrease of cladoceran (Moina micrura and Bosminopsis deitersi) density was also obeserved. At this time, small rotifers including Polyarthra spp. reached maximum density. Gut analysis of fish demonstrated that small-sized juvenile fish (< 15 mm in total length)preferred large rotifers as well as cladocerans, while large sized fish (> 15 mm)selected only cladocerans. On the other hand, juvenile Micropterus salmoides of which size was larger than other juvenile fish consumed not only zooplankton but also other small juvenile fish. Based on these results, the decline of large rotifers and cladocerans during early summer in the river seems to be result of predation by juvenile fish. However, the period when juvenile fish maintained their high density was as short as one month and the decreased density of cladocera rapidly recovered as soon as juvenile fish became scarce. Such a short period of juvenile fish devel-opment in the river can be attributed to the consumption of juvenile fish by the young-of-the-year cohorts as well as adults of M. salmoides. The high trophic state of the river might permit the rapid recovery of the cladoceran community. The predation impact of juvenile fish in the Nakdong River seems to be affected by the existence of piscivore as well as high trophic status.

• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
• /
• 2002.09a
• /
• pp.44-52
• /
• 2002

Low temperature thermal desorption (LTTD) has become one of the cornerstone technologies used for the treatment of contaminated soils and sediments in the United States. LTTD technology was first used in the mid-1980s for soil treatment on sites managed under the Comprehensive Environmental Respones, Compensation and Liability Act (CERCLA) or Superfund. Implementation was facilitated by CERCLA regulations that require only that spplicable regulations shall be met thus avoiding the need for protracted and expensive permit applications for thermal treatment equipment. The initial equipment designs used typically came from technology transfer sources. Asphalt manufacturing plants were converted to direct-fired LTTD systems, and conventional calciners were adapted for use as indirect-fired LTTD systems. Other innovative designs included hot sand recycle technology (initially developed for synfuels production from tar sand and oil shale), recycle sweep gas, travelling belts and batch-charged vacuum chambers, among others. These systems were used to treat soil contaminated with total petroleum hydrocarbons (TPH), polycyclic aromatic hydrocarbons (PAHs), pesticides, polychlorinated biphenyls (PCBs) and dioxin with varying degrees of success. Ultimately, performance and cost considerations established the suite of systems that are used for LTTD soil treatment applications today. This paper briefly reviews the develpoment of LTTD systems and summarizes the design, performance and cost characteristics of the equipment in use today. Designs reviewed include continuous feed direct-fired and indirect-fired equipment, batch feed systems and in-situ equipment. Performance is compared in terms of before-and-after contaminant levels in the soil and permissible emissions levels in the stack gas vented to the atmosphere. The review of air emissions standards includes a review of regulations in the U.S. and the European Union (EU). Key cost centers for the mobilization and operation of LTTD equipment are identified and compared for the different types of LTTD systems in use today. A work chart is provided for the selection of the optmum LTTD system for site-specific applications. LTTD technology continues to be a cornerstone technology for soil treatment in the U.S. and elsewhere. Examples of leading-edge LTTD technologies developed in the U.S. that are now being delivered locally in global projects are described.

• Journal of the Korea Institute of Information and Communication Engineering
• /
• v.19 no.9
• /
• pp.2197-2204
• /
• 2015

In recent times, the high-tech society has become the most important issue by IT technology and publication network. Today such flows have also been the case in the e-book field. Today's electronic publication is changing day by day. But there are some problems according to the prevalence of e-book. E-book is similar to p-book(paper-book). There is a limit to have perfect feeling of a texture of p-book. In order to purchase an e-book, people use online. People having malicious intent could copy and distribute it illegally. It leads to cyber abuses. This paper aims at the copyright protection of e-book ePub writers. The proposed e-book copyright protection system is designed using e-book production Sigil environment and C program environment. This system uses client-server communication through e-book ePub as authentication information. It discerns whether to permit or not for a client to read the e-book using authentication information. Authentication information includes ID, password, IP address, limited time of authentication information, GUID(Globally Unique Identifier). If authentication information about e-book meets requirements, people can use it. But if not, it blocks people's approach by quitting program.

• Economic and Environmental Geology
• /
• v.54 no.5
• /
• pp.505-513
• /
• 2021

Recently, housing prices in metropolitan areas is also increasing in the UK and Australia. Their governments are trying to solve this problem by the housing development in the quarry sites near cities. The cases reviewed in this study, Erith Hill Quarry (The Quarry), Plymstock Quarry, Lilydale Quarry (Kinley), and Bombo Quarry are the mixed-used development cases in the closed quarry sites through the urban planning system. In the UK, the local government uses the urban planning scheme such as the planning permit system, section 106. The local government permits the quarry site development on the condition that it provides necessary public facilities, such as schools and affordable housing for the local community. In Australia, local governments use up-zoning permission rights to convert land uses in quarries from industrial to mixed-use. Development plans have to include urban infrastructure and open space in addition to affordable housings. In the case of Australia, establishing a development plan in advance and filling the quarry pit with overburden through a phased development is expected to have the effect of reducing the project cost. Both countries think that developing brownfields, such as quarry sites, is a more sustainable and eco-friendly development from the perspective of future generations than developing new green fields. Such a perspective of the UK and Australia will be able to give policy implications for our slightly rigid urban development system.

• Proceedings of the Korean DIstribution Association Conference
• /
• 2002.05a
• /
• pp.31-59
• /
• 2002

Recently there are many changes of logistics environment Such as integrated logistics information system, the rapid growth of the domestic and international small package express service and third party logistics with Electronic Commerce. At this time it is very important to deliver to customers the goods sold through EC speedy, accurately and safely. That is to say, the role of small package express service is very important at EC times. The bottlenecks of small package express service in the circumstances of EC are the weakness of EC operating company and small package express service provider the shortage of distribution centre and cargo terminal, the shortage of skilled man with related small package express service etc. So, I suggested that for activation of EC it is necessary to strengthen the strategic alliances, introduce GPS and use the third party logistics positively in the side of small package express service provider. And it is necessary to prepare for the settlements of traffic problems, support the introduction of integrated logistics service, logistics information system, deregulate restriction such as weight limit of vehicles in the side of the government. And to government support throughout extending nation's SOC, deregulation, support to small package express service terminal, permit to stopping & parking in downtown, abolishing a no passing zone, permit to being employed foreigner. Also this service involves ensuring that the product will arrive when wanted, and in an undamaged condition.

• Journal of the Korean Society of School Health
• /
• v.7 no.1
• /
• pp.45-55
• /
• 1994

The purpose of this study is to contribute to improvement of educational environment by analysing all problems related to environment around the school. To accomplish this purpose, this study was carried out by examining the problems in controlling the areas required for cleanup with 220 teachers in charging the cleanup duties of the primary and secondary schools in Taegu between June 1 and July 15, 1993 and by actually surveying the prejudical business stores around 72 primary schools between August 10 and September 20, 1993. Although most teachers answered to the questionnaires that it is necessary to cleanup the bad environment around the school, the duties of its cleanup tend not to be considered as an important matter. The teachers considered that the most prejudical business store around the school is totally the game room, and in such order as comic books' store, liquor selling shop and causing noise and pollution. 57.3% of total respondents answered that the present cleanup movements have resulted in failure mostly because of both supervising authorities' careless promotion and store owners' excessive commercial transactions. The result of actual survey in environmental and sanitary cleanup area around 72 primary schools showed that the greatest number of 1,258 prejudical stores was the video tapes shop, and then in such order as lodgings, and game rooms, while the number of prejudical store by the schools was 17.5 stores per school on the average which showed a various distribution from zero to 77 places. In general, these prejudical stores were mainly located around the schools in Jung-gu and Seo-gu areas. In addition, it was shown that the more the number of students, the more the number of the prejudical stores. In order to improve the environment around the school, it is necessary to strictly carry out the zoning system relating to the usage of land, to strongly restrict the stores without permit and abnormal stores and to establish the basis asking the city development authorities to go through the environmental evaluation. Moreover, it is absolutely required to make efforts to establish the national right sense of education, and to closely cooperate with the related authorities.

• Korean Journal of Ecology and Environment
• /
• v.44 no.1
• /
• pp.75-84
• /
• 2011

We examined the effect of the turbid water on the periphytic diatom community in an artificial stream system. The artificial stream was constructed with transparent acryl and composed of four channels. Each channel ($20\;cm{\times}200\;cm{\times}40\;cm$) was supplied continuously with eutrophic lake water. In order to the freely colonize and grow diatoms, artificial substrate was installed with commercial slide glass soaked in 1% agar. Prior to introducing turbid water, the artificial stream was operated with lake water for 6 days to permit the propagation of diatom community on the substrates. The turbid water prepared with sediment sieved with ${\varphi}$ $64\;{\mu}m$ at $2\;g\;L^{-1}$ (final concentration, 300 NTU) was provided daily for 50 minute duration. The experiment was conducted for 7 days with manipulated experimental condition of light ($50{\sim}80\;{\mu}mol\;m^{-2}s^{-1}$, light:dark=24:0), temperature ($10{\pm}1^{\circ}C$), and flow rate ($0.31\;cm\;s^{-1}$). Sampling and analysis were conducted daily for water quality and diatom. Turbidity of the water varied 162.2~173.2 NTU during the experiment. After introduction of turbid water, DO, pH and TN were decreased, while SS and TP increased significantly. A total of 14 genera and 47 species of diatoms was observed on the artificial substrates during the experimental period. Of these, Navicula appeared to be a most dominant genus with 10 species, followed by Cymbella (6 species), Fragilaria (6 species) and Gomphonema (5 species). Achnanthes minutissima was the most dominant species (>70% of total frequency) in both control and treatment experiments. Increase in diatom abundance lasted for three days since turbid water introduction, after that they gradually decreased by the termination of the experiment. These results suggest that frequent supply of highly-concentrated turbid water significantly decreases the periphytic diatom community, and retard the recovery of the stable food-web within the stream.

• Journal of Technologic Dentistry
• /
• v.33 no.1
• /
• pp.93-102
• /
• 2011

Purpose: The study aimed to evaluate working environment for dental technician by measuring dust level, ventilation conditions and the use of personal protective equipment and to provide basic information required to improve working environment and develop health education programs for dental technician. Methods: A total of 240 dental technician who are registered with the Daegu Association of Dental technician and working at 34 dental laboratories participated in the study. And the dust level was measured at 21 different spots in 16 dental laboratories out of 34. Results: Of 34 dental laboratories, 31 (91.2%) were equipped with a ventilator, but the remaining 3 (8.8%) did not have a ventilator. By the number of ventilator, 1 to 3 ventilators were found in 22 dental laboratories (71.0%), 4 to 6 ventilators were in 7 laboratories (22.5%) and more than 7 ventilators in 2 laboratories(6.5%). According to the frequence of changing filters in dust collector, 20 dental laboratories (58.9%) changed filters every four weeks, 10 laboratories (29.4%) changed them every six weeks and 4 laboratories (11.7%) changed them every eight weeks. Of total respondents, 114 (61.3%) said they wore a mask all the time while working, 56 (29.6%) said they frequently wore a mask, 19 (10.1%) said they did not wear a mask. As for the type of masks, 159 (84.1%) used a disposable mask, 25 (13.2%) used a cotton mask and 5 (2.7%) used an anti-dust mask. For dust sat on their outfits while working, 102 (54.0%) shook their uniforms inside workplace to keep dust off the uniforms, 64 (33.9%) did not anything until they wash their uniforms and 23 (12.1%) shook their uniforms outside workplace to keep dust off the uniforms. Of total respondents, 182 (96.3%) had a particle in their eyes while carrying out grinding work. Based on the measurement of floating dust at workplace, 3 dental laboratories showed dust concentration exceeding the minimum level of 10 mg/$m^3$ allowed under the permit for environment. Of those, 1 laboratory had the dust concentration that was more than 1.5 times higher than the minimum level. Dust concentration was higher in laboratories that used a dust collector with 0.5 horse power and changed filters more than 3 weeks ago. Dust comprised of nickel (more than 70%), chrome (9%) and others. The mean chrome concentration was more than twice higher than the minimum permissible level of 0.5 mg/$m^3$. There were two laboratories that showed chrome concentration exceeding the level of 0.4 mg/$m^3$. Like dust concentration, chrome level was higher in laboratories that used a dust collector with 0.5 horse power and changed filters more than 3 weeks ago. There were six laboratories that had nickel concentration exceeding the minimum permissible level of 1 mg/$m^3$. Of those, one laboratory had nickel concentration that was more than three times higher than the minimum permissible level. Nickel concentration was also higher in laboratories that used a dust collector with 0.5 horse power and changed filters more than 3 weeks ago. Conclusion: It is not likely that heavy metal concentrations found in the study constitute respiratory dust. It is however necessary for health of dental technician to apply the Industrial Safety and Healthy Law to dental laboratories and make recommendations for the use of personal protective equipment, installation of a proper number of ventilators, more frequent change of filters in dust collector and improved ventilation for polishing work. At the same time, dental technician need education on how to use personal protective equipment and how to efficiently remove dust from their uniforms.

• Journal of Korea Water Resources Association
• /
• v.52 no.12
• /
• pp.975-984
• /
• 2019

As an essential prerequisite for systematic and integrated management of river water, it is necessary to secure the basic data such as discharge supplied to the river and released from the river. Under the current permit system for river water use, 59.1% of licensed facilities were found to have no discharge meters in 2017, especially for agricultural water, which makes it difficult to secure reliable data as a large portion of the reports are voluntarily reported by users. In this study, the indirect discharge measurement method of calculating the discharge through the power usage of the pumping station was applied to secure reliable discharge data. In particular, focusing on the fact that the discharge calculated by the power usage method differed with the actual discharge according to the level of the river, the study was conducted on improving the power usage method reflecting the river water level and improving the accuracy of discharge data. Analysis of the discharge calculated using the power usage method considering river water level using the correlation analysis method such as regression analysis, percent difference, root mean square error etc. confirmed that the results are not high compared to the conventional power usage method, but are slightly more approximated to the actual discharge. Therefore, although reliable discharge data can be obtained from the existing power usage method, it is expected that more accurate data on intaking water of river water can be obtained if the improved power usage method is used at points where the variation in the water level of the river is large.

• Development and Reproduction
• /
• v.12 no.1
• /
• pp.41-49
• /
• 2008

Ultrastructural changes occurring during the course of development and degeneration of oocytes in female Ruditapes philippinarum (Adams & Reeve, 1850) are described for clams collected from Gomso Bay, Korea. During the early stages of oogenesis, desomosome-like gap junctions localized between the early vitellogenic oocyte and the follicle cells. Vitellogenesis occurs through a process of autosynthesis, involving the combined activity of the Golgi complex, mitochondria and rough endoplasmic reticulum, and heterosynthesis in which extraovarian precursors are incorporated into oocytes by endocytotic activity, involving the basal region of the early vitellogenic oocytes prior to the formation of the vitelline envelope. The follicle cells appear to play an integral role in vitellogenesis and oocyte degeneration: phagocytosis and intracellular digestion of products originating from oocyte degeneration. These functions can permit a transfer of yolk precursors necessary to vitellogenesis, and they can accumulate nutrients in the cytoplasm, as glycogen and lipids, which can be employed by the vitellogenic oocyte. During the period of oocyte degeneration, follicle cells may have lysosomal system for breakdown, and resorb various phagosomes in the cytoplasm for nutrient storage. But follicle cells probably are not the major source of yolk precursors in vitellogenesis.