• The Journal of The Korea Institute of Intelligent Transport Systems
• /
• v.17 no.5
• /
• pp.1-13
• /
• 2018

Divers types of Personal Mobility(PM) are appeared on the market after the Segway is introduced. PMs have propagated very rapidly with their ease of use, and accidents related with PM show a sudden increase. Many studies on the PM are performed as its trend, but dring safety of passengers are excluded. In this study, criteria which can be adopted for PM's driving safety evaluation are reviewed. Also result of driving safety evaluation on 3 types of PM(wheel chair, kickboard, scooter(seating/standing) and walking using deducted criteria is given. COG(Center of the gravity) and SM(Stability Metric) are finally selected two criteria among many of them used in other fields. COG indicates how the center of mass deviates from the direction of the gravity. SM is a normalized value of generated force when PM moves as internal force, angular momentum, and ground reaction force. 0 means stop, and negative value means rollover, so it can be used for safety evaluation of PM. Average and standard deviation of measurement are standard of safety on the COG analysis. Wheel chair is the most safe and kickboard is the most unstable on the COG analysis. Wheel chair is also ranked as top safe on the SM analysis. Among two riding types(seating and standing) on the scooter, seating type is evaluated more safer than standing type. It is proposed that more various type of PMs are need to get safety evaluation for drivers and devices themselves together.

• Journal of the korean academy of Pediatric Dentistry
• /
• v.23 no.3
• /
• pp.640-658
• /
• 1996

The purpose of this study was to examine the mechanism of improving acid resistance of Nd-YAG laser irradiated tooth enamel and determine the most effective energy density for improving acid resistance. The bovine tooth enamel were lased with a pulsed Nd-YAG laser. The energy densities of exposed laser beam were varied from 10 to $70\;J/cm^2$. To investigate the degree of improving acid resistance by irradiation, all the samples were submerged to demineralize in 0.5 N $HClO_4$ solution for 1 minute. After 1 minute, 0.05 % $LaCl_3$ was added to the solution for interrupting the demineralization reaction. The amounts of dissolved calcium and phosphate in the solution were measured by using an atomic absorption spectrophotometer and the UV/VIS spectrophotometer, respectively. To examine the mechanism of improving acid resistance, X-ray diffraction analysis, infrared spectroscopy, and scanning electron microscopy were taken. The X-ray diffraction pattern of the samples were obtained in the $10^{\circ}{\sim}80^{\circ}2{\theta}$ range with $Cu-K{\alpha}$ radiation using M18HF(Mac Science Co.) with X-ray diffractometer operating at 40 KV and 300 mA. The infra-red spectra of the ground samples in 300 mg KBr pellets 10 mm diameter were obtained in the $4000cm^{-1}\;to\;400cm^{-1}$ range using JASCO 300E spectrophotometer. The scanning electron microscopy was carried out using JSM6400(JEOL Co.) with $500{\sim}2000$ times magnification. The results were as follow 1. The concentration of calcium dissolved from laser irradiated enamel with $50J/cm^2$ was significantly lesser than that of unlased control group (p<0.05) 2. From the result of the X-ray diffraction analysis, $\beta$-TCP, which increases acid solubility, was identified in lased enamel but the diffraction peaks of (002) and (004) became sharp with increasing energy density of laser irradiation. This means that the crystals in lased samples were grown through the c-axis and subsequently, the acid solubility of enamel decreased. 3. The a-axis parameter was slightly increased by laser irradiation, whereas the c-axis parameter was almost constant except for a little decrease at $50J/cm^2$. 4. In the infra-red spectra of lased enamels, phosphate bands ($600{\sim}500cm^{-1}$), B-carbonate bands (870, $1415{\sim}1455cm^{-1}$), and A-carbonate band ($1545cm^{-1}$) were observed. The amounts of phosphate bands and the B-carbonate bands were reduced, on the other hand, the amount of the A-carbonate band was increased by increase the energy density. 5. The SEM experiments reveal that the surface melting and recrystallization were appeared at $30J/cm^2$ and the cracks were observed at $70J/cm^2$. From above results, It may be suggested that the most effective energy density for improving acid resistance of tooth enamel with the irradiation of Nd-YAG laser was $50J/cm^2$. The mechanism of improving acid resistance were reduction of permeability due to surface melting and recrystallization of lased enamel and reduction of acid solubility of enamel due to decrease of carbonate content and growth of crystal.

• Economic and Environmental Geology
• /
• v.36 no.1
• /
• pp.39-48
• /
• 2003

The removal of chromate from aqueous solution using finely ground pyrite and biotite was investigated by batch experiments and the kinetics and the mechanism of chromate reduction were discussed. The chromate reduction by pyrite was about hundred times faster than that by biotite and was also faster at pH 3 than at pH 4. When pyrite was used, more than 90% of initial chromate was reduced within four hours at pH 4 and within 40 min. at pH 3. However, more than 400 hours was taken for the reduction of 90% of initial chromate by biotite. The results indicate that the rate of chromate reduction was strongly depending on the amount of Fe(II) in the minerals and on the dissolution rate of Fe(II) from the minerals. The reduction of chromate at pH 4 resulted in the precipitation of (Cr, Fe)(OH))$_3$$_{ (s)}$, which is believed to have limited the concentrations of dissolved Cr(III) and Fe(III) to less than expected values. When biotite was used, amounts of decreased Fe(II) and reduced Cr(Ⅵ) did not show stoichiometric relationship, which implying there was not only chromate reduction by ferrous ions in the acidic solution but also heterogeneous reduction of ferric ions by the structural ferrous iron in biotite. However, the results from a series of the experiments using Pyrite showed that concentrations of the decreased Fe(II) and the reduced Cr(Ⅵ) were close to the stoichiometric ratio of 3:1. It was because the oxidation of pyrite rapidly created ferrous ions even in oxygenated solutions and the chromate reduction by the ferrous ions was significantly faster than ferrous ion oxygenation.

• Journal of the Korean Society of School Health
• /
• v.10 no.2
• /
• pp.271-283
• /
• 1997

This study is designed for the school health education, contributing experience of life from middle school students from broken homes by describing specifically what they go through. And on this basis this study works out a grounded theory on the experience of life for middle school students from broken homes. The data was collected through a series of interviews with nine subjects singled out at each stage of research. With the permission of the subjects, the interviews were recorded and transcribed. The interviews lasted from 30 minutes up to one hour and 20 minutes. The in-depth interviewing methods and observations was used for data collection. The data was analyzed in the framework of grounded theory as mapped out by Strauss & Corbin (1990). By analyzing the materials eighty-three concepts were extracted, and they were united into 21 subordinate categories through the course of analysis. These were classified into nine precedence categories. The core category was found to be the adaptation of 'Wichookdem" or "Shrinkage". "Shrinkage" widows experienced was showed as the results "Self-reliance" and "Overcoming" through the course of generation and reaction, confrontation, and adaptation. According to the analysis findings of materials, the central phenomenon was showed as "shrinkage", the causal condition as "surprise", "Darkness", "Grudge", "Desolate", "Empty". The veins as presence of those around people and existence of support, and the meditate situation as self-support. For the strategy in solving "shrinkage", preparations of countermeasure and self-reinforcement were showed. And self-reliance and overcoming were the results. Through the contrast to the cases of ground materials, relation statements as follows were induced; (1) The weaker the suffering is, the weaker the "shrinkage" tends to be. (2) The stronger the suffering is, the stronger the "shrinkage" tends to be. (3) The more frequent and serious the suffering, the stronger the "shrinkage" tend to be. (4) The more infrequent and not serious the suffering is, the weaker the "shrinkage" tends to be. (5) The weaker the "shrinkage" is, the more self-control1ed the responses tends to be. (6) The stronger the "shrinkage" is, the more impulsive the responses tends to be. (7) The more satisfying the support is, the more self-controlled the responses to the "shrinkage" tends to be. (8) The more dissatisfying the support is, the more impulsive the responses to the "shrinkage" tends to be. (9) The more concrete the type of support is, the more self-controlled the responses to the "shrinkage" tends to be. (10) The more superficial the type of support is, the more impulsive the responses to the "shrinkage" tends to be. (11) The more self-controlled the responses are, the more self-reliant the subjects tends to be. (12) The more impulsive the responses are, the more conflict and wandering the subjects tends to be. (13) Whether the responses to the "shrinkage" express themselves in self-control or an impulse, it will be resulted in the form of either tension or pain. The following two were confirmed on the basis of repetitive relations; (1) If a subject's suffering is weak, infrequent and not serious, the "shrinkage" is weak. Also the subject's support is highly satisfying, and the support type is concrete. The responses to the "shrinkage" result in self-control which consequence is self-reliance with part. of it resulting in tension and pain. (2) If a subject's suffering is strong, frequent and serious, the "shrinkage" is strong. Also the subject's support is dissatisfying, and the support type is superficial. The responses to the "shrinkage" result in an impulsion whose consequence is wandering with part of it resulting in tension and pain. Through the results in this study, the following is to be suggested; O This research is basically aimed at analyzing the experience of the middle school students living in broken homes, for the more inclusive approach, the study for them is made systematically according to the type of their problems.

• Economic and Environmental Geology
• /
• v.43 no.1
• /
• pp.13-20
• /
• 2010

Acid mine drainage (AMD) from abandoned mine sites typically has low pH and contains high level of various heavy metals, aggravating ground- and surface water qualities and neighboring environments. This study investigated removal of heavy metals in a biological treatment system, mainly focusing on the removal by adsorption on a substrate material. Bench-scale batch experiments were performed with a mushroom compost to evaluate the adsorption characteristics of heavy metals leached out from a mine tailing sample and the role of SRB in the overall removal process. In addition, adsorption experiments were perform using an artificial AMD sample containing $Cd^{2+}$, $Cu^{2+}$, $Pb^{2+}$ and $Zn^{2+}$ to assess adsorption capacity of the mushroom compost. The results indicated Mn leached out from mine tailing was not subject to microbial stabilization or adsorption onto mushroom compost while microbially mediated stabilization played an important role in the removal of Zn. Fe leaching significantly increased in the presence of microbes as compared to autoclaved samples, and this was attributed to dissolution of Fe minerals in the mine tailing in a response to the depletion of $Fe^{3+}$ by iron reduction bacteria. Measurement of oxidation reduction potential (ORP) and pH indicated the reactive mixture maintained reducing condition and moderate pH during the reaction. The results of the adsorption experiments involving artificial AMD sample indicated adsorption removal efficiency was greater than 90% at pH 6 condition, but it decreased at pH 3 condition.

• Tuberculosis and Respiratory Diseases
• /
• v.43 no.6
• /
• pp.965-975
• /
• 1996

Background : Exogenous lipoid pneumonia is caused by inhalation or aspiration of animal, vegetable or mineral oil. Most cases are ascribed to aspiration of oil in laxatives or nose drops Petroleum, another pure hydrocarbon used as a base in various medications, is occasionally involved. Especially animal oil produces severe tissue inflammatory reaction, but most patients present with only abnormal chest X-ray and no specific clinical symptoms or signs. Method: Seven patients, 3 males and 4 females, with exogenous lipoid pneumonia, who was hospitalized or referred to pulmonary division at Samsung Medical Center from December 1994 10 July 1996, were included. They hadn a history of laking shark liver oil(so-called "squalene") for varying period of time. We reviewed clinical, radioloic and pathologic findings. Result: Patients look 7 to 30 capsules of "squalene" a day for at least one month to 5 years. Six cases had chronic disease such as diabetes, hypertension, or cerebrovascular accident. Respiratory symptoms of mild fever, cough and sputum were present in 3 cases and in 3 cases there was no clinical symptoms and signs but abnormal findings by chest X - ray. The major radiologic findings by simple chest X - ray and computed tomography consisted of consolidation, infiltration involving mainly right middle and both lower lobes, and ground-glass opacity. Five of six bronchoscopic examinations demonstrated both lipid droplets floating on the surface of bronchoalveolar lavage fluid and Lipid-laden macrophages in bronchoalveolar lavage fluid or lung tissue. Follow-up chest X -ray showed improvement in 4 cases but no marked interval change in 3 cases after removal of exposure to "squalene". Conclusion: Shark liver oil can induce lipoid pneumonia in adults. In case of high clinical suspicion, confirmation of "squalene" use by careful history taking is required and bronchoscopy is helpful in diagnosis.

• Journal of Korean Society of Forest Science
• /
• v.77 no.3
• /
• pp.259-268
• /
• 1988

For the purpose of examining the effects of simulated acid rain on nutrient contents of plant tissues in Pintos densiflora seedlings and Forsythia koreana rooted cuttings, the experimental design of randomized block arrangement with three replications was implemented in the experimental field of Yesan National Agricultural Junior College. One-year-old Pinus densiflora seedlings and Forsythia koreana cuttings were planted in the pots filled the mixed soils(nursery soil : forest soil of siliceous sandy loam=1 : 1 v/v) in the early spring of 1986. The regime of artificial acid rain, in terms of spray frequency per month and spray amount at single treatment per plot, was simulated on the basis of climatological data averaged from 30 years records. Simulated acid rain(pH 2.0, pH 4.0, and pH 5.5 as control) containing sulfuric and nutric acid in the ratio of 3 : 2(chemical equivalant basis) diluted with ground water were treated on the experimental plants under condition of cutting off the natural precipitation with vinyl tunnel, during the growing season(May 1 to August 31) in 1986. The results obtained in this study were as follow : (1) As for the nitrogen contents in plant tissues, P. densiflora increased significantly in one-year-old stembranch and root tissues, and F. koreana increased significantly in leaf and root tissues, as the pH levels of acid rain decreased. (2) The available phosphate contents in root tissues of P. densiflora, and in leaf and root tissues of F. koreana were significantly decreased, as the pH levels of acid rain decreased. (3) $K_2O$, CaO and MgO contents in plant tissues were significantly decreased in the both species as the pH levels decreased. And the effects of acid rain on F. koreana were higher than those of P. densiflora. (4) Sulfur contents of plant tissues in the both species were increased at pH 2.0 treatment. There were significant differences among three acid rain treatments in leaf and root tissues of P. densiflora, and in all parts of F. koreana. (5) In the effects of simulated acid rain on the both species and the tested soils, in general, F. koreana revealed higher sensitiveness than P. densiflora, and the lower pH levels of simulated acid rain were treated, the more sharp reaction was showed.

• Journal of Food Hygiene and Safety
• /
• v.29 no.4
• /
• pp.340-346
• /
• 2014

In this study, the detection method was developed using real-time PCR to distinguish 4 species (bovine, porcine, horse, and chicken) of raw meats. The genes for distinction of species about meats targeted at 12S rRNA and 16S rRNA parts in mitochondrial DNA. Probes were designed to have a 5' FAM and a TAMRA at the 3' end. This study is to develop 4 species-specific primer and probes about raw materials and real-time PCR on 10 strains to observe the products of non-specific signal for similar species. As a result, any non-specific signal were not detected among each other. Real-time PCR method was developed for quantitation and identification of intentional and unintentional mixture in ground mixed meat (The difference of $C_T$ value between intentional mixture and 100% meat: $${\leq_-}$$ cycles, The difference of $C_T$ value between unintentional mixture and 100% meat: $${\geq_-}$$ cycles). The detection and differentiation of intentional and unintentional mixture in this study would be applied to food safety management for eradication of adulterated food distribution and protection of consumer's right.