• Parasites, Hosts and Diseases
• /
• 제55권5호
• /
• pp.565-568
• /
• 2017

An oval-shaped mass with a smooth surface was found in the ear canal of a 22-month-old male infant. Although the mass appeared to be almost entirely blocking the ear canal, it was successfully removed under a surgical microscope without general anesthesia at the outpatient department. Under an optical microscope with hematoxylin and eosin staining, the specimen was observed to have a cuticle with a serrated surface and a pore canal, as well as parts of the capitulum, salivary glands, muscles, midgut, and the legs. The specimen was identified as a hard tick of the family Ixodidae, based on gross and histological findings. This paper is the first report in Korea on the diagnosis and treatment of a tick bite in the ear canal.

• 환경생물
• /
• 제36권1호
• /
• pp.33-42
• /
• 2018

인도네시아의 열대 이탄지는 황폐화되고 농경지 및 조림지로 전용되어왔다. 수로는 열대 이탄지의 지하수위를 관리하고 작물의 생산성을 높이기 위해 설치되었으나, 열대 이탄지의 구조를 파괴하고 침하 및 산불 발생 위험을 증가시켰다. 이에 따라, 인도네시아 정부는 수로로 인한 문제를 막기 위한 정책과 모라토리엄을 마련하였다. 그리고 해당 정책들에 따라 이탄지 재습지화에 관한 시범사업들이 일부 수행되었다. 우리나라가 열대 이탄지를 재습지화 한다면 추후 탄소 배출권을 확보할 수 있는 가능성이 있으므로, 적절한 재습지화에 관한 자료가 필요하다. 이에 따라, 본 연구에서는 열대 이탄지에 적용되는 정책의 흐름을 조사하고 이 시범사업들의 설치 계획, 고려사항, 댐 설계, 재료, 설치 방법, 모니터링 방법, 그리고 소요 시간 및 비용 등에 대해 분석하였다. 이탄층의 깊이가 3 m 이상인 지역은 개발이 제한되고 개발 허가 발급이 중단되었으며, 복원을 위한 수로차단이 설치되었다. 이 지역에서는 댐의 지속성과 지역 이해당사자들의 참여를 독려하는 것이 우선순위로 여겨졌다. 개발 허가지역의 경우에는 개벌과 화전이 금지되었으며, 지하수위를 유지하기 위한 수로차단에 목적을 두었고, 수로차단을 설치할 때에는 작업 및 비용의 효율성이 우선적으로 고려되었다. 조사 결과를 바탕으로 본 연구에서는 인도네시아 열대 이탄지의 규제 적용 및 수로차단 설치 시 적용할 수 있는 방안들을 제시하였다. 이러한 결과는 동남아시아 지역의 배수된 열대 이탄지에 적합한 수로차단을 계획하는 데 기여할 수 있을 것으로 사료된다.

• Restorative Dentistry and Endodontics
• /
• 제21권1호
• /
• pp.267-279
• /
• 1996

Microorganisms are implicated the endodontic treatment failures. Persistent endodontic infection may be the result of retention of microorganisms in the dentin of the root canal walls. Dentinal tubules of the root canal walls have been shown to harbor microorganisms. The purpose of this study was to investigate the invasion of microorganism into the root dentin and dentinal tubules. The effects of irrigation solutions and smear layer on bacterial colonization of root canal were evaluated using a scanning electron microscopy. Canals of extracted human teeth with single and straight canals were stepback prepared using normal saline. Tooth samples were divided into four groups according to the irrigation solutions -5 % sodium hypochlorite and normal saline-and smear layer treatment. The smear layer was removed by 5% NaOCl and 20% EDTA for 10 min respectively. After sterilization, they were incubated with each strains of Streptococcus sanguis, Enterococcus faecalis, Staphylococcus aureus and Escherichia coli. Sodium hypochlorite solution reduced the adhesion of microorganisms effectively compared to normal saline. The smear layer inhibited colonization of E. faecalis, S. aureus and E. coli in the root canals due to their blocking of dentianl tubules. But S. sanguis invaded dentinal tubules in the root canals without smear layer. It was suggested that bacterial attachment might be different according to the strains. Sodium hypochlorite inhibited bacterial attachment in the dentinal tubules dramatically. The absence or presence of smear layer affected bacterial invasion of the dentinal tubules.

• 대한의용생체공학회:의공학회지
• /
• 제41권1호
• /
• pp.22-27
• /
• 2020

Auditory stimuli are commonly used in various electroencephalogram experiments, also in EEG-based brain-computer interface systems. However, using conventional earphones that blocks the ear canal attenuates or even blocks external environmental sound which might cause loss of crucial information from surroundings. Instead, bone-conductive earphones are able to deliver sound through vibration without blocking the ear canal. To investigate the feasibility of the bone-conductive earphones for auditory-stimuli based experiments, we compared N100 event-related potential features as well the event-related spectral perturbation and inter-trial coherence of auditory steady-state response between conventional and bone-conductive earphones. The results showed no significant differences between bone conduction and conventional earphones regardless of distinct sound pressures. This result shows that bone conductive earphones can be used for auditory experiments when the environmental sound is crucial to the user.

• Geomechanics and Engineering
• /
• 제33권2호
• /
• pp.155-165
• /
• 2023

Hurricane Katrina swept New Orleans, Louisiana, USA, in 2005, causing more than 1,000 fatalities and severe damage to the flood protection system. Recovery activities are complete, however, clarifying failure mechanisms and devising resilient and cost-effective retrofitting techniques for the flood protection system are still of utmost importance to enhance the general structural integrity of water retaining structures. This study presents extensive centrifuge test results to find various failure mechanisms and effective retrofitting techniques for a levee system. The result confirmed the rotational failure and translational failure mechanisms for the London Ave. Canal levee and 17^th St. Canal levee, respectively. In addition, it found that the floodwalls with fresh waterstop in their joints perform better than those with old/weathered waterstop by decreasing pore water pressure build-up in the levee. Structural caps placed on the top of the joints between I-walls could also prevent local failure by spreading the load to surrounding walls. At the same time, the self-sealing bentonite-sand mixture installed along the riverside of floodwalls could mitigate the failure of floodwalls by blocking the infiltration of seepage water into the gap formed between levee soils and floodwalls.

• 한국산학기술학회논문지
• /
• 제18권10호
• /
• pp.696-706
• /
• 2017

본 연구는 소하천에 설치된 암거를 대상으로 유송잡물 집적 빙지를 위한 저감시설에 대한 실험검증 연구이다. 암거는 도심지 내부나 도심을 통과하는 도로와 철도 아래에 인공수로를 만들기 위해 매설하는 구조물로 정의되며, 일반적으로 도로암거와 수로암거로 구분된다. 이중 수로암거는 유수를 하천으로 배출하기 위해 인공적으로 조성되는 구조물로 홍수시 토사 또는 나뭇가지나 잡풀과 같은 유송잡물의 집적으로 인해 구조물의 안정성을 저해하고 단면폐색으로 인한 월류위험성에 노출되어 있다. 이러한 유송잡물로 인한 피해를 예방하기 위해서는 유송잡물 저감시설은 반드시 필요하다. 본 연구에서는 수리실험을 통해 기존 재시된 3가지 유송잡물 저감시설의 효과를 검토하였다. 실험결과 유송잡물을 우회시키는 방식인 수직분리대를 설치할 경우 설치전에 비해 집적률은 27.65% ~ 31.39% 감소하는 효과가 있었으며, 유송잡물 차단이 목적인 스크린과 우회스크린은 유송잡물의 종류에 관계없이 높은 차단효과를 보였다. 그러나 수위상승에 대한 영향을 복합적으로 검토하였을때 우회스크린방식이 우수한 효과를 보이는 것으로 나타났다. 이러한 스크린빙식은 차단 효과는 좋으나 집적으로 인한 수위상승 위험성이 높아 지속적인 유송잡물의 회수를 고려해야 할 것으로 판단된다.

• Asian Pacific Journal of Cancer Prevention
• /
• 제13권12호
• /
• pp.5937-5946
• /
• 2012

The term endocrine disruptors is used to describe a variety of natural and manmade substances that have the capacity to potentially interfere with and modify the normal physiology of endocrine system either by mimicking, blocking or modulating the actions of natural endogenous hormones. The rising incidence of breast cancer over the last 50 years and the documented higher incidence in urban as compared to rural areas suggest a relationship to the introduction and increased use of xenoestrogens in our environment. The literature has developed over the last decades where initial experiments on endocrine disruptors did not support an involvement in breast cancer, and then evidence mounted implicating various environmental factors including hormones, endocrine disrupting chemicals and non-endocrine disrupting environmental carcinogens in the pathogenesis of breast cancer. Available data support the hypothesis that exposure to endocrine disruptors in utero leaves a signature on mammary gland morphogenesis so that the resulting dysgenic gland becomes more predisposed to develop tumors upon exposures to additional insults later on during life. Exceptionally, exposure to phytoestrogens could be beneficial to human health. Most of the available data are from well developed countries while the developing countries are still understudied regarding these issues. Here, we raise a note of caution about potential role of environmental toxins including endocrine disruptors in breast cancer development and call for serious measures to be taken by all involved parties in the developing world.