• Journal of the Korea Concrete Institute
• /
• v.15 no.3
• /
• pp.361-368
• /
• 2003

As the supply of aggregate needed in the construction site becomes difficult due to preservation of environment and exhaust of aggregate resource, a research for replacement aggregate in shortage is being actively progressed and a copper slag is also a kind of replacing aggregate. To use copper slag as fine aggregate of concrete, many studies are already conducted in each of the advanced countries and in the state of applying these at the site. In the year of 2000 a Korea industrial standard of Copper slag aggregate for concrete was established in our country so that this can be applied in the construction site. This study is to find out whether copper slag is equipped with the physical and chemical requirements for the use in concrete aggregate, and to analyze the dynamic properties of copper slag concrete that replaces 25, 50, 75, 100% of fine aggregate. Copper slag study not only satisfies the using condition of fine aggregate, but also reveals high level of physical property compared to ordinary concrete up to 50% of sand replacement rate. In the future after confirming the durability of concrete using copper slag, it is judged to be advantageous for the preservation of environment to use this as a replacement material for natural aggregate.

• Journal of Ecology and Environment
• /
• v.42 no.1
• /
• pp.20-29
• /
• 2018

Background: For various reasons such as agricultural and economical purposes, land-use changes are rapidly increasing not only in Korea but also in the world, leading to shifts in the characteristics of local carbon cycle. Therefore, in order to understand the large-scale ecosystem carbon cycle, it is necessary first to understand vegetation on this local scale. As a result, it is essential to comprehend change of the carbon balance attributed by the land-use changes. In this study, we attempt to understand accumulated soil carbon (ASC) and soil respiration (Rs) related to carbon cycle in two ecosystems, artificially turned forest into pastureland from forest and a native deciduous temperate forest, resulted from different land-use in the same area. Results: Rs were shown typical seasonal changes in the alpine pastureland (AP) and temperate deciduous forest (TDF). The annual average Rs was $160.5mg\;CO_2\;m^{-2}h^{-1}$ in the AP, but it was $405.1mg\;CO_2\;m^{-2}h^{-1}$ in the TDF, indicating that the Rs in the AP was lower about 54% than that in the TDF. Also, ASC in the AP was $124.49Mg\;C\;ha^{-1}$ from litter layer to 30-cm soil depth. The ASC was about $88.9Mg\;C\;ha^{-1}$, and it was 71.5% of that of the AP. The temperature factors in the AP was high about $4^{\circ}C$ on average compared to the TDF. In AP, it was observed high amount of sunlight entering near the soil surface which is related to high soil temperature is due to low canopy structure. This tendency is due to the smaller emission of organic carbon that is accumulated in the soil, which means a higher ASC in the AP compared to the TDF. Conclusions: The artificial transformation of natural ecosystems into different ecosystems is proceeding widely in the world as well as Korea. The change in land-use type is caused to make the different characteristics of carbon cycle and storage in same region. For evaluating and predicting the carbon cycle in the vegetation modified by the human activity, it is necessary to understand the carbon cycle and storage characteristics of natural ecosystems and converted ecosystems. In this study, we studied the characteristics of ecosystem carbon cycle using different forms in the same region. The land-use changes from a TDF to AP leads to changes in dominant vegetation. Removal of canopy increased light and temperature conditions and slightly decreased SMC during the growing season. Also, land-use change led to an increase of ASC and decrease of Rs in AP. In terms of ecosystem carbon sequestration, AP showed a greater amount of carbon stored in the soil due to sustained supply of above-ground liters and lower degradation rate (soil respiration) than TDF in the high mountains. This shows that TDF and AP do not have much difference in terms of storage and circulation of carbon because the amount of carbon in the forest biomass is stored in the soil in the AP.

• Journal of the Korean Recycled Construction Resources Institute
• /
• v.4 no.2
• /
• pp.180-186
• /
• 2016

There are many apartment buildings with the government's policy of increasing the supply of residential houses in Korea. Roughly 60% of the Korea population are living in apartment buildings. Since the 1970s, the Korean economy has grown enormously, the economic and social structure was radically transformed to industrialization and urbanization step. A village has grown into a large town in Korea and apartment buildings was constructed to solve national housing shortage by the Korean government and the construction company. Since the 2000s, this apartment buildings which was built in the 1970s and 1980s had become gradually deteriorated. So, reconstruction and remodeling project of apartment buildings have been come into request in Korea. There are two way to improve the residential environment. The one is remodeling of apartment buildings and the other is reconstruction of that. Therefore, we carried out questionnaire and survey study of the preference on the reconstruction and remodeling of old aged apartment which were located in daejeon province. As a result, the preference rate of remodeling is increasing instead of reconstruction because reconstruction of apartment buildings takes more money and needs long construction period.

• Journal of the Korean Recycled Construction Resources Institute
• /
• v.4 no.4
• /
• pp.404-417
• /
• 2016

The purpose of this study is to examine the extent to which the deterioration in strength of high strength concrete of 60MPa replaced by a large amount of recycled coarse aggregates (more than 60% to 100% of replacement ratio) could be recovered with steel fiber reinforcement through material compressive strength test and shear failure test on short and middle beams and then to offer useful data for aggregate supply system of a sustainable resource circulation type. This study first examined the results of previous related tests. The results of the material compressive strength tests confirmed that when using a combination of steel fiber reinforcements of volumn ratio 0.75% and high quality recycled coarse aggregates with an water absorption rate within 2.0%, the strength characteristics of high strength concrete of 60MPa level were not only restored to the strength level of concrete made with natural aggregates, but also showed superior ductility. And the shear failure tests on short and middle beams using recycled coarse aggregates more than 60% with shear span to depth ratio (a/d) of 2 and 4 controlled by shear forces mainly confirmed that effects of superior shear strength increase and ductile behavior characteristics were showed by steel fiber reinforcements.

• Journal of the Korean Data and Information Science Society
• /
• v.24 no.4
• /
• pp.763-771
• /
• 2013

Due to a decrease in the number of college prep students which was triggered by the low birth rate since 1990, it is predicted, beginning 2016, that the entrance quota for colleges will exceed the number of applicants for college admissions. This serious imbalance between supply and demand raises serious problems for the regional universities, many of which have already been struggling to recruit new students and even considered closing down the schools. In an effort to securing best high school students, many of the schools have been developing various unique and specialized selectional processes for the applicants. In this research, through a statistical analysis of special admission processes for vocational high school students who were admitted to a regional state-run university (University A), I tried to find a way to effectively deal with the student management. Statistically analyzing these first-year students' enrollment and their adjustment processes as well as the departmental relationships and gender differences, I tried to find some better ways to secure good applicants. It is expected that this study will not only be utilized as guide to adopt a way to bypass the enrollment quota in order to secure talented students but also be served as a reference that will help the students adapt themselves to school life until they graduate. It is also expected that this study will be expanded in such a way as to compare it with other models and even develop a new type of college entrance system that would fit future college admission policies.

• Journal of the Economic Geographical Society of Korea
• /
• v.18 no.2
• /
• pp.168-189
• /
• 2015

The job creation has been the most pressing issue after financial crisis in many countries around the world. Various policies for creating jobs have been implemented in order to revitalize regional economy in Korea. It has been known that the jobs have been created more in low-wage and part-time work than high-wage and full-time work. The purpose of this study is to analyze the differentiation of startups job in local labor market areas(LLMAs) in terms of job quantity as well as job quality. As the spatial unit, 121 local labor market areas which were delineated based on self-containment rate(demand and supply side of labor market) and numbers of resident workers are used. Also due to difference of the size of employment, LLMAs are classified into 3 groups: large, Medium, small LLMAs. The major results are as follows: First, the characteristics of the job creation are varied among 3 groups in terms of the quantitative and qualitative aspects. Highly waged and highly value-added jobs have been created more in large LLMAs, but full-time jobs created more in small LLMAs. Secondly, the job creation of LLMAs is somewhat weakly correlated to regional economic performance. While the quality of jobs is correlated to regional economic performance in Medium LLMAs, the quantity of jobs is significantly correlated to regional economic performance in small LLMAs. The results of this research give some implications for implementing the effective policy to create jobs related to regional economy, indicating that differentiated strategies for 3 groups of LLMAs is critically important.

• Advances in pediatric surgery
• /
• v.16 no.2
• /
• pp.154-161
• /
• 2010

Pulmonary sequestration (PS) is a rare congenital malformation of the lower respiratory tract. The anomaly is characterized by absence of communication with the tracheobronchial tree and isolated blood supply from an anomalous systemic vessels. With the utilization of antenatal ultrasound, the diagnosis of asymptomatic neonatal PS has increased. Treatment options include observation, arterial embolization and surgical resection. The aim of the present study is to review the clinical course of PS and to share our experience with thoracoscopic resection. A total of 96 patients with PS were treated at Asan Children's Hospital between 1999 and 2010. The diagnosis of PS was established by CT in the cases managed by observation or embolization, and by tissue pathology in the surgical cases. Medical records and radiographic images were retrospectively reviewed. Thirty-nine patients were managed by embolization and 30 patients by surgery. The remaining 27 patients have been under observation without any procedures. Among 27 observation patients, 1 patient regressed completely and 10 patients were lost to follow up. Of the 39 embolizations patients, 2 had their lesion regress and sepsis was suspected after embolization. In 1 patient, the microcoil migrated to the iliac artery during the embolization procedure, and another patient developed renal abscess caused by renal artery embolization. Among 30 surgical cases, resection by thoracotomy was performed in 27 at the Department of Thoracic Surgery, and thoracoscopic resection in 3 at the Division of Pediatric Sugery. Only one wound complication ocurred. We conclud that surgical excision should be recommended for pulmonary sequestration, whether the sequestration is symptomatic or not because of the risk of infection, the low rate of natural regress, poor compliance, severe complications after embolization, and to exclude other pathology. In summary, thoracoscopic resection of the pulmonary sequestration is feasible, efficacious, safe and cosmetically superior even in neonatal period.

• Journal of the Korean Geographical Society
• /
• v.48 no.2
• /
• pp.303-319
• /
• 2013

The purpose of this paper in the case of elementary and middle schools in Hwaseong city is that clarify spatial structure by seasonal changes of supply region of school meal foods and changes in food mileage. This paper used account registers of school meal foods of the subject schools as data for this analysis. And this paper analyzed data in March, June, September, and December in order to understand seasonal changes of school meal foods. The spatial structure of school meal foods in elementary and middle schools in Hwaseong city take four with private contracts, limited competition, and bidding quotation by suppliers. With the crops in Hwaseong city, they consist of eco-friendly vegetables in Gyeonggi-do, domestic eco-friendly vegetables and fruits, general vegetables and fruits, and imported processed foods and agricultural products. In case of food mileage, around Hwaseong city, there are spatial structure with about 17 $ton{\cdot}km$, 26 $ton{\cdot}km$, and 11,000 $ton{\cdot}km$ respectively. The spatial structure of school meal foods supplies was determined by difference in feed rate of crops, eco-friendly agricultural products, imported processed foods, and imported agricultural products.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
• /
• 2018.10a
• /
• pp.329-331
• /
• 2018

In this paper, we propose a monitoring system that starts with the supply of raw materials for threading, is processed into a lathe machine, and checks for defects of the product are automatically performed by the robot with Smart Factory technology through assembly and disassembly. Completion check according to the production instruction quantity and production instruction is made by checking the production status according to whether or not the raw material is worn by the displacement sensor, and checking the pitch and the contour of the processed female and male to determine OK and NG. The robotic system acts as a relay for loading and unloading of raw materials, pallet transfer, and overall process, and it acts as an intermediary for organically driving. The location information of the threaded products is collected by using the non-contact wireless tag and the energy saving system Production efficiency and utilization rate were checked. The environmental sensor collects the air-conditioning environment data (temperature, humidity), measures the temperature and humidity accurately, and checks the quality of product processing. It monitors and monitors the driving hazard level environment (overheating, humidity) of the product. Controls for CNC and robot module PLC as a heterogeneous system.

• Korean Chemical Engineering Research
• /
• v.50 no.3
• /
• pp.391-397
• /
• 2012

The depletion of conventional oil reserves and the increasing energy need in developing countries such as China and India result in exceeding oil demand over supply. As a solution of the problem, the efficient utilization of heavy oil has been receiving more and more interest. In order to utilize heavy oil, upgrading processes are required. Among the upgrading processes, thermal decomposition is thought to be relatively simple and economical. In this study, to understand basic characteristics of thermal decomposition of heavy oil, we conducted pyrolysis experiments of deasphalted oil (DAO) produced by a solvent deasphalting process. DAO is a mixture of many components and consists mainly of materials of carbon number 20~40. For the comparison with results of DAO pyrolysis, additional pyrolysis experiments with single materials of carbon number 30 ($C_{30}H_{62}$, $C_{30}H_{58}O_4S$, $C_{30}H_{63}O_3P$) were conducted. Pyrolysis experiments were carried out non-isothermally with variation of heating rate (10, 50, $100^{\circ}C$/min) in a thermogravimetric analyzer. Average pyrolysis activation energy determined by using Arrhenius method, Ingraham and Marrier method, and Coats and Redfern method was 72~99 kJ/mol. In the activation energy calculated by Ozawa-Flynn-Wall method, DAO had wider variation than other single materials.