• Journal of Chest Surgery
• /
• v.39 no.5 s.262
• /
• pp.394-398
• /
• 2006

Background: Goal of the initial treatment of primary spontaneous pneumothorax is re-expansion of the lung by evacuation of air from pleural space. Authors thought small caliber catheter could reach to this goal instead of conventional large bore chest tube. This retrospective study was undertaken to assess the effectiveness of 7-French (Fr) catheter for the initial treatment of primary spontaneous pneumothorax. Material and Method: Between May 2003 and April 2005, 111 patients with primary spontaneous pneumothorax were managed with tube drainage; 7 Fr catheter for 86 patients and 24-French chest tube for 25 patients. We analyzed catheter indwelling time, use of analgesics, re-expansion of the lung, and catheter related problems by medical records. Result: Mean catheter indwelling time was $2.4{\pm}1.1$ days in 7 Fr group and $2.3{\pm}1.3$ days in chest tube group (p>0.05). All patients with 24 Fr catheter needed analgesics injection but never in 7Fr group. Complete re-expansion of the lung based on plane chest radiograph was obtained in 77% of 7 Fr group. The problem related with 7 Fr catheter was kinking, which showed in 5.6%. Conclusion: Application of the 7 Fr catheter for initial management of primary spontaneous pneumothorax was as effective as 24 Fr catheter.

• The Transactions of The Korean Institute of Electrical Engineers
• /
• v.67 no.1
• /
• pp.8-15
• /
• 2018

New methodology for probabilistic reliability based grid expansion planning of HVDC in power system including Wind Turbine Generators(WTG) is developed in this paper. This problem is focused on scenario based optimal selection technique to decide best connection bus of new transmission lines of HVDC in view point of adequacy reliability in power system including WTG. This requires two kinds of modeling and simulation for reliability evaluation. One is how is reliability evaluation model and simulation of WTG. Another is to develop a failure model of HVDC. First, reliability evaluation of power system including WTG needs multi-state simulation methodology because of intermittent characteristics of wind speed and nonlinear generation curve of WTG. Reliability methodology of power system including WTG has already been developed with considering multi-state simulation over the years in the world. The multi-state model already developed by authors is used for WTG reliability simulation in this study. Second, the power system including HVDC includes AC/DC converter and DC/AC inverter substation. The substation is composed of a lot of thyristor devices, in which devices have possibility of failure occurrence in potential. Failure model of AC/DC converter and DC/AC inverter substation in order to simulate HVDC reliability is newly proposed in this paper. Furthermore, this problem should be formulated in hierarchical level II(HLII) reliability evaluation because of best bus choice problem for connecting new HVDC and transmission lines consideration. HLII reliability simulation technique is not simple but difficult and complex. CmRel program, which is adequacy reliability evaluation program developed by authors, is extended and developed for this study. Using proposed method, new HVDC connected bus point is able to be decided at best reliability level successfully. Methodology proposed in this paper is applied to small sized model power system.

• Journal of the Korea Concrete Institute
• /
• v.20 no.6
• /
• pp.689-696
• /
• 2008

The purpose of this study was to evaluate the alkali-silica reactivity for aggregates in Korea according to test methods: accelerated mortar bar test (AMBT) by ASTM C 1260; chemical test by KS F 2545 (ASTM C 289). The results are as follows: The AMBT (ASTM C 1260) results showed that two (2) igneous rocks (two mica granite and felsite), three (3) sedimentary rocks (arkose, red sandstone and shale), two (2) metamorphic rock (slate and vitric tuff), one (1) mineral (quartz) showed more expansion than 0.1% at 14 days. But, some sedimentary rocks and metamorphic rocks expanded more than 0.1% at 28 days even though they were less than 0.1% at 14 days. Therefore, it is necessary to extend the experimental dates more than 14 days to evaluate the possibility of alkali-aggregate reactivity. The chemical test (KS F 2545) results showed that five (5) igneous rocks (andesite, diabase, granite porphyry, muscovite granite and diorite) were indicative of potentially deleterious expansion, while two (2) igneous rocks (diorite porphyry and quartz porphyry) were possible indicative of expansion, and three (3) igneous rocks (biotite granite, two mica granite and felsite) were indicative of innocuous reactivity. The above results showed that the results from chemical method (KS F 2545) and AMBT (ASTM C 1260) had little relationship.

• Journal of KIISE:Databases
• /
• v.32 no.3
• /
• pp.297-303
• /
• 2005

When confronted with a query, question answering systems endeavor to extract the most exact answers possible by determining the answer type that fits with the key terms used in the query. However, the efficacy of such systems is limited by the fact that the terms used in a query may be in a syntactic form different to that of the same words in a document. In this paper, we present an efficient semantic query expansion methodology based on a question category concept list comprised of terms that are semantically close to terms used in a query. The semantically close terms of a term in a query may be hypernyms, synonyms, or terms in a different syntactic category. The proposed system constructs a concept list for each question type and then builds the concept list for each question category using a learning algorithm. In the question answering experiments on 42,654 Wall Street Journal documents of the TREC collection, the traditional system showed in 0.223 in MRR and the proposed system showed 0.50 superior to the traditional question answering system. The results of the present experiments suggest the promise of the proposed method.

• Journal of the Korean Society for Library and Information Science
• /
• v.43 no.4
• /
• pp.139-161
• /
• 2009

This study explored the services of libraries for babies and toddlers and the possibilities of service expansion through Bookstart as a cooperation system for libraries. This study presented the problems of the services of libraries for toddlers by implementing the questionnaire method and the in-depth interviews. In addition, this study showed the impact of carrying-out this program and why libraries should manage the Bookstart program. Results indicated that: (1) even though the membership enrollment standard of children's libraries is usually from babies and toddlers up to the elementary school students, that of a few libraries is still over elementary school students. This will work on restraining the services of libraries for users, especially toddlers, only 54.8% of libraries services are for the toddlers; (2) by analyzing the perception of librarians, we get to know that librarians think that the age of the first use of a library is more appropriate for kindergarten-agers than toddlers; (3) librarians think positively about the Bookstart and that libraries are more suitable for Bookstart than any other institutions; (4) after the introduction of Bookstart to libraries, many changes happened in respect of the function of libraries and the types of users. For examples, there was an expansion of users to babies and toddlers and their parents, an increase in users, focusing on early-childhood reading education and the strengthening of the role of librarians as program planners in particular. This study suggests that the introduction of Bookstart would bring changes to the concept of traditional libraries and the inflexible attitudes of librarians.

• Polymer(Korea)
• /
• v.37 no.5
• /
• pp.557-562
• /
• 2013

The thermal expansion and mechanical properties of diglycidyl ether of bisphenol A (DGEBA) with mercaptan hardeners were studied by a comparative method with an amine-adduct type hardener. Thermal expansion and dynamic mechanical properties were measured by thermo mechanical analysis (TMA) and dynamic mechanical ananlysis (DMA), respectively. The $T_g$ and the coefficient of thermal expansion (CTE) of epoxy/amine-adduct type hardener system were $82.6^{\circ}C$ and 71.2 $ppm/^{\circ}C$, respectively. As the number of -SH functional group of mercaptan hardener increased, the $T_g$ rapidly decreased and gradually increased up to ca. $80^{\circ}C$ and the CTE under the $T_g$ rapidly increased to ca. 200 $ppm/^{\circ}C$ from 80 $ppm/^{\circ}C$ and decreased to ca. 100 $ppm/^{\circ}C$. The crosslinking density of epoxy with amine-adduct type hardener was ca.1.5 $mol/cm^3$, while that of epoxy with mercaptan hardeners increased from 1.0 to 1.7 $mol/cm^3$, as the number of -SH functional group increased. The storage modulus can increase up to 2700MPa at $30^{\circ}C$.

• Resources Recycling
• /
• v.27 no.2
• /
• pp.38-47
• /
• 2018

Integrated gasification combined cycle (IGCC) is a next generation energy production technology that converts coal into syngas with enhanced power generation efficiency and environmental performance. IGCC produces almost coal gasification slag as the solid by-product. IGCC slag is generated about 140,000 tons for a year although recycling of it is still in the early stages. We evaluated the potential of IGCC slag which is generated from a pilot plant in South Korea as an alkali-activated cement. Samples which were activated with the combined activator of sodium silicate solution and caustic soda had an average compressive strength of 4.5 MPa, showing expansion. Expansion of the alkali-activated slag was presumed to be caused by free CaO in the slag, although it was not detected by the ethylene glycol method. Samples that were activated with the combined activator of sodium aluminate and caustic soda had an average compressive strength of 10 MPa. Hydroxy sodalite and $C_3AH_6$ were found to be the new crystalline phases. IGCC slag can be used as an alkali-activated material, but the strength performance should be improved with proper mix design approach to calculate optimum proportions which can alleviate the expansion issue at the same time.

• Journal of the Korean Geosynthetics Society
• /
• v.16 no.2
• /
• pp.149-158
• /
• 2017

Permeating injection is commonly known as an ideal type of injection in grouting reservoir embankment, yet often-combined permeating and fracturing injection grouting operation can disturb the original soil. A grouting method has been regarded as effective and developed to ameliorate the possible disturbance problem. It involves compaction grouting with low expansive pressure near the injection hole and repetitive injection and compaction with grout material that allows ideal permeating injection. This thesis develops Hybrid Grout (ie. HG grout) that allows various application in any ground condition combined together, has high fineness and low viscosity, and expands permeation injection to silty sand. It researches on the injection effect of permeable compaction grout which is done with PC packer and is a combination of HG grout and expansion agent to obtain permeation compaction effect on the area near grout injection spot by developing Permeable Compaction Type Packer(ie. PC packer). As the developed PC packer, HG grout, and and expansion agent (HI-E) are applied to reservoir embankment reinforcement grouting, possibile permeation compaction effect that satisfies reservoir embankment grouting standard is confirmed according to the research.

• Journal of the Korean Geosynthetics Society
• /
• v.17 no.4
• /
• pp.141-155
• /
• 2018

Recently, the number of ground subsidence resulting from underground cavity has been increased. Accordingly, the importance of restoration of stress release zone around the underground cavity has been emphasized. The stress release zone is composed of low density soils having extremely low stiffness and degree of compaction, which can lead to additional cavity expansion and collapse of overlying ground. Therefore, in this study, the suitability of restoration method of underground cavity using expansive material for reinforcement of stress release zone around the cavity is verified. The basic physical properties and expansion characteristics of the expansive material were examined. The experiment equipment capable simulating of stress release zone was developed and is used to investigate the effect of expanding material on stress release zone. The stress release zone was simulated using the spring in numerical analysis. The factors of the volume ratio of the underground cavity to the expansion material, the degree of stress relaxation, and the shape of the cavity were varied in numerical simulations, and the behavior of stress release zone was analyzed based on the numerical analysis results. Analysis variables are factors that affect each other. Also, filling of underground cavity and capacity of restoration of stress release zone were confirmed when the expansive material was inserted into underground cavity.

• Journal of the Society of Disaster Information
• /
• v.17 no.1
• /
• pp.60-67
• /
• 2021

Purpose: Traditional markets often have irregular space utilization patterns because the spaces are created and divided as time passed. Internally, there is high risk of fire due to problems such as aging facilities and high-density of stores and externally, there is high risk of fire spread since it is often adjacent to deteriorated residential and commercial facilities. Method: In this paper, on-site investigations were carried out to check fire risk factors and fire spread risk, and fire occurrence and expansion risk factors were investigated for traditional markets in Hwanghak-dong and Dong-daemun by using large-scale fire data from existing traditional markets. Result: As a result of the analysis, there are likely to be various problems such as high fire load and lack of safety awareness due to aging facilities and high-density of stores. In particular, it is necessary to prepare countermeasures because deteriorated residential facilities with narrow alleys around traditional markets have high fire spread. It is situation that while traditional markets mainly are managing for fire and disaster centering on the merchant association, the surrounding residential areas are not properly managed. Conclusion: It is necessary to manage deteriorated residential facilities with traditional markets, also to be linked early warning system and information to evacuate rapidly in case of fire there.