17 research outputs found
Epidemiological and experimental studies on pinworm infestation in Korea
No full text의학과/석사Pinworm (Enterobius vermicularis) infestation in present day Korea has become one of nationwide problems. Chyu and Kim(1959), Seo and Lim(1963) and Lee at al. (1964) reported the incidence of pinworm infestation in Korea to be about 20 percent.
It may be worthwhile to study epidemiologically what is the main reason for such a high incidence both in rural and urban areas. The author made an investigation on the incidence of pinworm infestation for 72 families of 207 (male 128, female 79)
rural inhabitants in Kyunggi Province, 115 families of 502 (male 297, female 205) upper class inhabitants of Seoul, 58 families of 296 (male 140, female 156) suburban inhabitants of Seoul and 799 (male 446, female 353) orphans accommodated in 14 orphanages in Seoul and Kyunggi Province. Epidemiological factors of pinworm
infestation as well as biological characters of the ova of Enterobius vermicularis were also studied.
The result are summarized as follows:
1. Familial incidence in Seoul and rural areas was 48.6 percent in average.
2. 38.2 percent of suburban inhabitants of Seoul and 30.9 percent of rural inhabitants were infested with pinworm, and the incidence for the children of orphanages was the highest with 54.2 percent while 13.3 percent of upper class of Seoul was the lowest.
3. There was no noticeable difference of incidence between male and female for the upper class of Seoul and rural area, but for the suburban area of Seoul it was slightly higher in female.
4. There was no relationship between the family size and the incidence.
5. Children infested with pinworm seemed to play an important factor for the high incidence in individual family.
6. Number of rooms in a family and number of persons in each room seemed to have an influence on pinworm infestation.
7. The ova were found in 16.7 percent out of 90 dust samples collected from the living rooms of Seoul suburbs and 4.5 percent of them appeared in matured condition.
8. The immature ova required 24 hours to develop to matured stage in Spring, and 18 days were needed in Automn at the similar level of room temperature.
9. The higher the temperature, the sooner the ova developed to a matured form, taking 45 minutes at 50℃, 4 hours at 37℃, 5 hours at 35℃, 20 hours at 30℃, 22 hours at 24℃ and 450 hours (about 18 days) at 18℃.
10. 30.6 percent of ova were still alive after being kept in 4±2℃ for 10 days and larva in egg shell was motile for 48 hours in iced water.
11. In tap water under room temperature the ova generally become matured state in 3 days and gradually destroyed following automatic excystation.
12. The ova survived for 24 hours in various concentrations of detergents with the survival rate of 40 percent in 2% cleaning soap, 30 percent in Ⅰ Ⅳ solution of sodium hydroxide and more than 50
13. The ova were completely destroyed within 48 hours in 30% solution of sodium of them survived for 24 hours in vinegar and sauce did not have any ovicidal action. 10gm% of look, garlic, red pepper and mustard showed appreciable ovicidal effect during the period of 4 days.restrictio
무게 중심 보로노이 분할을 이용한 그래프 기반의 효율적인 환경 표현 및 경로 생성}{무게 중심 보로노이 분할을 이용한 그래프 기반의 효율적인 환경 표현 및 경로 생성
No full textDoctorA scalable environment representation is important for a mobile robot when seeking appropriate paths in a large environment. A probabilistic roadmap (PRM) has an advantage of abstracting the traversable area information of a large environment because unoccupied regions and their connectivities are represented by several nodes and edges, respectively.In this thesis, we present an efficient graph-based environment representation for a mobile robot path planning by solving problems of the PRM. First, a centroidal Voronoi tessellation-based probabilistic roadmap (CVT-PRM) is proposed. The CVT-PRM is constructed by rearranging nodes using the node rearrangement method. It iteratively updates the positions of nodes using a concept of the centroidal Voronoi tessellation.The CVT-PRM covers traversable areas almost completely and divides them evenly, and the CVT-PRM-based path planner can search an appropriate path more promptly than a grid-based path planner. Second, a hierarchical roadmap (HRM) is proposed. The HRM has a multi-layered structure to represent traversable areas. In the HRM, a region-roadmap abstracts the topological relation of subegions in an environment, and a local-roadmap represents traversable areas in each subregion. The incremental construction process of the HRM expands the traversable area information by extracting new subregions when a mobile robot navigates unknown regions.An efficient path planning method is also proposed using the multi-layered structure of the HRM. The divide-and-conquer (DNC) method locally seeks an appropriate path to reduce search space. The HRM-based path planner with the DNC method can search an appropriate path more promptly than a PRM-based path planner because the search space size of the HRM-based planner is much smaller than that of the PRM-based planner. Last, the sampling-based retraction (SbR) is proposed. The SbR improves the safety of the initial path planning result by removing unsafe sections in the initial path. In the SbR, each waypoint is iteratively updated to maximize its clearance by indirectly modeling clearance around it using several random samples
An Efficient Mobile Robot Path Planning Using Hierarchical Roadmap Representation in Indoor Environment
No full text1
Surface Resistivity Modification of Polyimide Film by Plasma Process
No full textDoctorPlasma-based ion implantation (PBII) is known an effective technique to modify the material surface among various ion implantation methods. The ballistic-mode PBII was developed to modify the surface resistivity of polymer. Repetitive high-voltage pulses are applied to the grid a few centimeters from a polyimide (PI) film in the ballistic-mode PBII. The high-voltage pulse applied to the grid has the peak values of -20 ~ -30 kV, width of a few µs, rise time of 1.5 µs and fall time of 0.5 or 40 µs. The surface resistivity of PI film was improved by the argon gas ballistic-mode PBII technique for Electrostatic Dissipation (ESD) application. The surface resistivity of PI film was changed from 1016 Ω/square to ESD range of 106 ~ 109 Ω/square by the ballistic-mode PBII. The PI film treated by the ballistic-mode PBII maintains the surface resistivity of ESD range after many days, acetone test and at the high temperature of 200 ̊C. Many ion dose and high ion energy show a good performance to modify the material surface. In this process, the efficiency of surface resistivity modification depends on the fall time of the pulse applied to the grid immersed in plasma.In-line process system was developed based on experimental results performed in the prototype system of the ballistic-mode PBII. The plasma was produced by the 13.56 MHz RF discharge in the vacuum chamber with Ar gas pressure of 10-3 ~ 10-4 Torr. Electron density measured by cutoff probe was in the order of 109 cm-3. The surface resistivity of ~108 Ω/square was achieved in the continuous process for the ESD PI film rolls having 514 mm width and 300 m length. The properties of the PI film untreated and treated by a ballistic-mode PBII were nearly same except the surface roughness
