• Proceedings of the Computational Structural Engineering Institute Conference
• /
• 2007.04a
• /
• pp.771-776
• /
• 2007

Widespread propagation of failure can be triggered by localized damage to a structure because of fires, impact and explosion etc. In this paper, the progressive collapse analysis program is developed to automatically check the failed members and construct the modified structural model at each step. OpenSees, that is widely used in many research groups, was used for the developed progressive collapse analysis control program. The control program developed in this study automatically computes the damage indices of all the structural members and performance a progressive collapse analysis after the first failed member is selected. Using the developed program, we compared the progressive collapse behaviors of the example structures considering dynamic effects or not, and the difference of progressive collapse mechanism according to the modeling method of the failed members.

• Proceedings of the KIEE Conference
• /
• 1999.07a
• /
• pp.443-445
• /
• 1999

본 연구에서는 고도의 전문가 수준에서 역구내 상황을 고려하여 실시간 전자연동처리전략을 수립함으로써 열차운행을 안전하고 정확하게 제어 열차충돌이나 탈선 등의 사고를 사전에 방지함으로써 보다 높은 안전도가 보장될 수 있도록 지원하는 전문가 시스템이 제안된다. 전문가 시스템은 열차의 역구내 운행시 신호기, 전철기 궤도회로 등의 입력정보로부터 연동 지식베이스에 근거하여 신호설비들간의 연쇄관계를 확인, 실시간 연동전략을 수립하며, 연동규칙을 정확하고 효과적으로 표시할 수 있도록 규칙기반 시스템으로 구현된다. 특히, 제어실패시 논리적 추론기능과 협조하여 합리적인 진로를 제시함으로써 비상시 역무원이 당황하지 않고 신속하고 안전하게 연동업무를 처리할 수 있도록 한다.

• Journal of the Korean Magnetics Society
• /
• v.5 no.3
• /
• pp.197-202
• /
• 1995

고주파용 전원의 필요성이 대두되면서 고주파에서 낮은 자기손실을 가진 재료의 개발이 요구되고 있다. Mn-Zn 페라이트의 자기손실은 전기비저항의 증거나 소결시 미세구조의 제어로 줄일 수 있다. 본 연구에서는 연쇄고온합성법(Self-propagation High- temperature Synthesis)에 의해 제조된 $_Mn_{0.72}$Z $n_{0.22}$)$_{0.94}$ (F $e_{2}$ $O_{3}$)$_{1.06}$ 조성의 Mn-Zn페라이트에서 첨가물이 미세구조와 자기적 성질에 미치는 영향에 대해 조사하였다. $SiO_{2}$와 Ca $Co_{3}$의 복합첨가에 의해 미세구조의 미세화와 아울러 낮은 자기손실 특성을 얻을 수 있었다. 그러나 첨가 물의 과다 첨가시에는 비정상입자성장 조직이 나타났으며 자기적 성질이 현저히 저하 하였다. 전기비저항, 자기손실의 주파수 의존 결과에 근거하여 주된 자기손실기구 및 이에 미치는 첨가물 효과에 대해 논하였다.

• Restorative Dentistry and Endodontics
• /
• v.17 no.1
• /
• pp.115-125
• /
• 1992

It is advisable to use irrigation solutions which have strong antibacterial effect and weak cytotoxic effect on treating root infections. Streptococci are ones of the most frequently isolated microorganisms in infected root canals. The antibacterial effect of ten irrigation solutions were investigated on S. mutans (19449), S. sanguis. )10556) and 4 streptococci isolated from saliva of healthy persons. These streptococci were exposured to irrigation solutions during 10 sec, 30 sec,. 1 min, 3 min, 5 min, 10 min, 30 min and 2hrs respectively. Four irrigation solutions which showed strong antibacterial activity were diluted to 1 : 1 to 1 : 10,000. Then they were subcultured on blood agar plate an observed after 1 day. 5.25% NaOC1 had the strongest antibacterial effect. 30% urea and normal saline showed no antibacterial effect. 50 % citric acid and 3% $H_2O_2$ showed relatively weak antibacterial effect. 15 % EDTA had very weak antibacterial effect.

• Korean Journal of Veterinary Research
• /
• v.44 no.4
• /
• pp.643-648
• /
• 2004

Efficacy of ciprofloxacin was evaluated in laboratory and field studies for control of streptococcal infection in flounder and eel. In disc diffussion test, all streptococcal strains showed high sensitivity to the ciprofloxacin. Minimum inhibitory concentrations of ciprofloxacin against all streptococcal strains used in this study were less than $0.195{\mu}g/ml/$. In laboratory studies where fishes were challanged with Streptococcus iniae, significant reductions in mortality were observed among fish receiving ciprofloxacin (in fed) at 100 mg/kg/body weight or more daily for 3 d when compared with mortality of non-medicated controls. Similar results were achieved when 100 mg/kg/body weight of ciprofloxacin was used in field trials.

• Journal of Korean society of Dental Hygiene
• /
• v.17 no.4
• /
• pp.613-620
• /
• 2017

Objectives: The purpose of this study is to investigate the antibacterial effect of Streptococcus mutans of tea tree ingredient. Methods: The experimental groups were each given with different concentrations (30 or 50 vol%) of tea tree prepared in saline solution. The control group applied only saline solution. The tea tree coating of the specimen were examined under a scanning electron microscope. For the antibacterial activity test of the tea tree, the contact angle of the tea tree- coated specimen's surface was analyzed. The antibacterial effect against Streptococcus mutans was determined by counting the colony forming units (CFU). The statical statics were evaluated by using one-way ANOVA and paired t-test. Results: The tea tree treated group of hydrophilic more than non treated group. Antibacterial experiments demonstrated that tee tree solution was effective against Streptococcus mutans. However there was no significant difference in depending solution concentration groups. Conclusions: The antimicrobial activity of the tea tree containing solution showed its potential for use as coating for denture and medical materials.

• Journal of Korean society of Dental Hygiene
• /
• v.23 no.4
• /
• pp.227-234
• /
• 2023

Objectives: Cetylpyridinium chloride CPC-based mouthwashes are well known to have no harmful ingredients in the mouth and can be used for a long time. The purpose of this study was to evaluate the effect of using CPC-based mouthwashes to suppress the biofilm formation and antibiotics for handling orthodontic appliances. Methods: To measure the antibacterial effect, Streptococcus mutans (S. mutans) cultured orthodontic appliances were precipitated in Gargreen and Polident for 5 minutes, incubated at 37℃ for 24 hours(h). In order to measure the biofilm removal effect, the degree of biofilm formation on the orthodontic appliances was stained with a methylene blue and the difference before and after was compared using image J software program (NIH Image J; NIH, Bethesda, MD). Results: The viability of S. mutans according to the concentration showed that Gargreen and Polident inhibited colony formation compared to the control, respectively (p<0.01). The degree of biofilm formation was significantly higher in the control, however both Gargreen and Polident significantly reduced it compared to the before and after condition on removable orthodontic appliances (p<0.01). Conclusions: This study suggests that the use of Gargreen, a cetylpyridinium chloride based oral cleaning cleanser, could be replaced by Polident for antibacterial effect and biofilm formation on removable orthodontic appliances.

• 한국벤처창업학회:학술대회논문집
• /
• 2022.11a
• /
• pp.89-93
• /
• 2022

정보통신기술(ICT - Information and Communications Technology)의 발달, 정부와 민간의 스타트업 발굴 및 투자 규모의 확대로 인해 혁신적인 아이디어를 기반으로 우수한 성과를 창출하는 스타트업들이 증가하고 있다. 이를 롤모델로 삼고 창업을 준비하는 예비 창업자들도 지속적으로 증가하고 있으나, 성공을 경험으로 연쇄창업을 도전하는 창업자와 달리 초기 스타트업들은 팀원 채용, 기술 개발, 자금 유치 등 다양한 문제에 직면하게 된다. 엑셀러레이터는 스타트업들이 직면하게 되는 다양한 문제 해결을 돕기 위해 교육, 멘토링, 컨설팅, 네트워크 연계, 초기 투자 등의 활동을 통해 스타트업이 성장할 수 있도록 멘토와 투자자의 역할을 동시에 수행한다. 본 연구의 목적은 스타트업의 특성과 창업성과과 어떠한 상관관계를 가지고 있는가를 조사하고, 엑셀러레이터의 역할이 스타트업의 창업성과에 매개역할을 하는지 분석 하는데 있다. 최근 국내에서는 다시 벤처 붐이 일어나고 있으며, 유니콘 기업의 양적 질적 증가, 정부 지원을 통한 초기 스타트업의 성과 등 창업생태계에서 의미 있는 지표들을 볼 수 있다. 스타트업의 성과와 관련된 지표들은 직/간접적으로 엑셀러레이터와 관련이 있으나, 그동안 국내에서 창업성과에 영향을 미치는 요인을 스타트업의 창업가의 기업가정신이나 창업가의 역량을 기반으로 주로 연구하였다. 따라서 본 연구에서는 스타트업의 특성으로 대표되는 독립변수 혁신성, 조직 문화, 재무적 특성, 네트워크 지향성과 학습지향성이 종속변수인 창업성과에 영향을 미칠 것이라는 가설을 검증하며 매개변수인 엑셀러레이터의 역할의 효과를 확인하고자 한다.

• Journal of Energy Engineering
• /
• v.21 no.1
• /
• pp.109-117
• /
• 2012

The climate industry could be defined as the group of industries responding to world climate change compacts. This study confined it to renewable energy and analyzed the economic impacts of Korean renewable industry, using 2009 Input-Output Table. This study estimated that Korean renewable industry made the production-induced impact of 1.1644 won(Korean money), and the value-added-induced impact of 0.3544 won through an increase in output growth of 1 won. Its job-creation impact is analyzed to correspond to 10.065 labors through an increase in output growth of 1 billion won. And its industrial linkage effects including forward and backward ones are analyzed not to be so great as expected. According to these results, some policies vitalizing Korean renewable industry and relating industries to its value-chain as new growth engines are recommended.

• KDI Journal of Economic Policy
• /
• v.13 no.4
• /
• pp.155-177
• /
• 1991

The promotion of economic exchange and cooperation between North and South Korea is significant in two ways. First, the pursuit of economic interest can lead gradually to the unification of the national economies. Second, economic relations can serve as the first stride toward political reunification. There are, however, many difficulties in conceiving a strategy for economic cooperation between North and South Korea because of their differences in ideology and socio-economic system. Under these circumstances, a bid by either the North or the South to consider its specific ideology or socio-economic system absolute and to impose them on the other side would inevitably lead to confrontation and collision and deepen the division of the country. Therefore, steps to expand and develop economic and technological cooperation and comprehensive exchanges between the North and the South, with due regard to the development of bilateral relations, are in full accord with the interests of the both sides. It is clear that North Korea's changing attitude toward its environmental conditions is neither a policy of opening nor an ideological shift toward pragmatism, as has occurred in the Eastern European countries. Instead, it is a temporary tactic for breaking out of the economic stagnation caused by its rigid economic structure. In this light, we must.