• Journal of Korean Elementary Science Education
• /
• v.22 no.1
• /
• pp.121-129
• /
• 2003

The enhancement of inquiry skills has been emphasized as a important objective of science education for a long time. Of these, the observation is not only a simple and basic skill, but also a very important skill, in aspect of gathering informations about the nature of all things around us, through interaction between the sense organs of body and objectives. The purpose of this study is to investigate the results of observations about the grasshopper(Oxya chinesis), made by the elementary student from the 3rd to the 6th grade, and to make use of them as the basic materials for the observative teaming and the evaluation of the observation ability. Through this study, the collected items of observation are as follows For grasshopper, a total of observation items is 95, 70 using the sight sense, 13 using the tactile sense,7 using the olfactory sense. 3 using the palate sense and 2 using the auditory sense. In this study, the findings of elementary student's observation are as follows. 1. On the whole, most of students have observed mainly by the sight and the tactile sense, when observing the grasshopper. 2. It is showed a tendency that the observation ability of student is increased with the higher grade in elementary school. 3. As the grade ascends. the observations with operating are increased, also the quantitative expression and interpretation about them are increased. 4. In the case of same grade, there is no significant difference between students' gender, though girls' ability of the observation showed somewhat higher than boys' 5. Occasionally, the interpretations on the observative facts made by student, are inaccurate. Basis on the above results, we suggested some directions for the improvement of the observative learning program in science classroom of elementary school. First, the teacher have to serve as a guide and encouragement in the observative learning class, to be accomplished the various observation, which all the sensory organ can be used by student than the sight sense. Second, to get elevated the ability of observation, it is necessary that some experimental tools(magnifying lens, stereoscope, auxiliary implements etc.) are utilized. Third, the teacher have to make often endeavors showing an example of operation, to be activated the atmosphere of operative observation.

• Restorative Dentistry and Endodontics
• /
• v.20 no.2
• /
• pp.671-684
• /
• 1995

The purpose of this study was to compare the apical sealing ability, overfilling and obturation of lateral canals using two gutta-percha techniques: Thermafil obturators and cold lateral condensation. Eighty numbered epoxide blocks with one major and five lateral canals were divided into four experimental groups and obturated according to experimental groups. Four experimental groups were as follows: Group 1 : Filling with Thermafil plastic obturators and sealer(ThermaSeal) Group 2 : Filling with Thermafil plastic obturators only, without sealer(ThermaSeal) Group 3 : Fillng using lateral condensation with sealer(AH-26) Group 4 : Fillng using lateral condensation without sealer(AH-26) All the blocks were stored in 100% relative humidor at room temperature for 7 days. Each block was placed in centrifuge tube filled with India ink, and then centrifuged for 20 minutes at 3,000 rpm. Apical leakage was measured from the apical foramen to the most coronal level of dye penetration in millimeter under a stereoscope. The length of gutta-percha and sealer in each of the lateral canals was measured, too. The presence or absence of overfilling of gutta-percha and sealer was recorded. The data was analyzed by one-way ANOVA. The obtained results were as follows: l. Apical dye leakage was almost: not occurred in Group Willed with Thermafil and sealer) and Group 3(filled using lateral condensation with sealer), and there was no significant difference in linear leakage between two groups(p>0.01). 2. In both Thermafil and lateral condensation groups, linear leakage of Group I, 3(filled with sealer) was less than that of Group 2, 4(filled without sealer), and there was no significant difference in linear leakage between Group 1, 2, 3(p> 0.01). 3. Overfilling during obturation of Group 1, 2(filled with Thermafil) was more than Group 3, 4(filled using lateral condensation), and there was no significant difference between groups(p> 0.05). 4. Groups filled with Thermafil had significantly more gutta-percha than groups filled using lateral condensation in all lateral canals(p <0.01), the total length of gutta-percha and sealer found in all lateral canals were similar in Group 1 and Group 3.

• Restorative Dentistry and Endodontics
• /
• v.18 no.1
• /
• pp.205-213
• /
• 1993

The purpose of the study was to evaluate the degree of the marginal leakage of esthetic restorative materials on root caries restoration. 120 cavities were prepared to $90^{\circ}$ butt joint on all margins on the crown and root portion, and divided into 4 groups. The four groups of cavity were filled with Amalgam(Dongmuyung Dental Alloy Co., Ltd, KOREA), Silux$^{(R)}$(3M Co., USA)-Scotch Bond 2$^{(R)}$(3M Co., USA), Silux$^{(R)}$-All Bond$^{(R)}$(BISCO USA), and GC Fuji II$^{(R)}$(G-C Co., JAPAN) respectively. The apical margin of the preparation was finished to leave a flash of restorative material. The coronal margin of the preparation was finished not to leave a flash of restorative material. All specimens were sectioned longitudinally with Isomet Low speed saw(Buether Ltd, USA). The degree of dye penetration was evaluated as the parameter of marginal leakage under the stereoscope. The results were as follows. 1. At the enamel and dentin/cementum margins, the margin were finished to leave a flash of material showed less marginal leakage than that were finished not to leave a flash of material (P<0.001). 2. The enamel margins showed less marginal leakage than the dentin/cementum margins(P<0.001). 3. There was no significant difference in the degree of the marginal leakage between Silux$^{(R)}$-Scotch Bond 2$^{(R)}$ group and Silux$^{(R)}$-All Bond$^{(R)}$ group.

• Restorative Dentistry and Endodontics
• /
• v.17 no.1
• /
• pp.95-103
• /
• 1992

The purpose of this study was to evaluate the effect of the dentin pretreatment on the marginal leakage of a glassionomer cement. 1n this study, 60 molars with sound and healthy crown portion were used. The dentin surface of these teeth were exposed and polished with 600 grit silicon carbide paper. Square - shaped cavities were prepared on the flattened dentin surfaces and these were divided into 4 groups according to the dentin pretreatment procedures. Group I : Dentin pretreatment with distilled water as a control group. Group II : Dentin pretreatment with 5% sodium hypochlorite solution. Group III : Dentin pretreatment with Ketac conditioner. Group IV : Dentin pretreatment with 40% polyacrylic acid. The degrees of dye penetration in the cavity walls were assessed using a stereoscope at ${\times}40$ magnification according to the maximum dye penetration. The results were analyzed by using Mann - Whitney U test. The results were as follows : 1. All groups showed varying depth of dye penetration. 2. Distilled water group showed the most severe marginal leakage when compared with the other groups(P<0.05). 3. 40% polyacrylic acid group showed the least amount of marginal leakage compared with the other groups (P<0.05). 4. There were significant differences between Goup I(distilled water) and Group IV (40% polyacrylic acid)(P<0.05), but there were no significant differences among Group I(distilled water), Group II(sodium hypochlorite), Group III(Ketac conditioner) (P>0.05).

• Restorative Dentistry and Endodontics
• /
• v.19 no.1
• /
• pp.205-216
• /
• 1994

The purpose of this study is to evaluate of apical plug materials for the contral of extrusion and sealing ability of high-temperature thermoplasticized gutta-percha in plastic root canal blocks. Seventy seven plastic blocks with canal preformed were instrumented with # 50K file 1 mm beyond apical foramen. Blocks were randomly divided into 5 groups of 15 blocks each. Group 1 was filled by high-temperature thermoplasticized gutta-percha only. The another 4 groups were placed with apical plug materials each other and then remaining space was back filled with high temperature thermoplasticized gutta-percha Apical plug materials were used as follows; Group 2: Thermoplasticized gutta-percha (Thermoplasticized gutta-percha group) Group 3 :. Calcium hydroxide powder (Calcium hydroxide group) Group 4 : Silver point (Silver point group) Group 5 : Gutta-percha cone softened by chloroform (Gutta-percha cone group) All the blocks were stored in 100 % relative humidor at room temperature for 14 days. Filling material extruded was removed carefully and then weighed in analytic balance. Each block was placed in centrifuge tube filled with India ink, and then centrifuged for 20 minutes at 3,000 rpm. Apical leakage was measured from the apical foramen to the most coronal level of dye leakage in millimeter by two examiners under a stereoscope. The data were analysed statistically by Student's t-test The obtained results were as follows; 1. The amounts of material extruded through the foramen decreased in all of groups used apical plug materials (P<0.01). 2. Silver point group and gutta-percha cone group were similar linear leakage to high-temperature thermoplasticised gutta-percha technique only (P>0..5). 3. Calcium hydroxide group and thermoplasticized gutta-percha group showed more liner leakage than high-temperature thermoplasticized gutta-percha only (P<0.01, P<0.05). 4. High-temperature thermoplasticized gutta-percha technique with silver point and gutta-percha cone as apical plugs showed less linear leakage and less extrusion of filling material.

• Restorative Dentistry and Endodontics
• /
• v.23 no.1
• /
• pp.20-42
• /
• 1998

The present study was designed to understand the basic principles of the laser system and to assess the optimal coditions of the Nd:YAG laser irradiation system in order to expand the use of the laser system in the dental field. The laser system used in this study was a pulsed-wave output type and the power level is 9 watts. The incisors of developing rats were irradiated with the laser system explained above for 0.5, 1, and 2 seconds giving energy density 71, 167, and 215 J/$cm^2$ respectively. The rats were sacrificed just after irradiation or 10 minutes and 10 days after irradiation. The specimens were examined with the stereoscope, light microscope and transmission electron microscope. The results are as follows: 1. The tissue removal efficiency (depth of the cavity formed) is increased with the energy density after Nd:YAG laser irradiation. 2. The carbonized area is increased with the energy density. Cracks and melted appearance are seen in all kinds of the energy densities. 3. The lacunae in the damaged alveolar bone by the laser irradiation were empty, while those in the newly formed bone were occupied with the osteocytes. The damaged alveolar bone was repaired by the osteoblasts and macrophages on the periphery of the bone matrix. 4. The damaged enamel was replaced by the loose connective tissues showing many kinds of cells. The ameloblasts were differntiated on the replaced loose connective tissue. 5. The damaged dentin was repaired by the irregular dentin formed by the odontoblasts differentiated from the mesenchymal cells migrated from the pulp core.

• The Korea Journal of Herbology
• /
• v.32 no.2
• /
• pp.33-40
• /
• 2017

Objectives : This study is aimed at establishing the discriminative criteria for Adenophorae Radix (AT; Sasam), Codonopsis Lanceolatae Radix (CL; Yangyu) and Adenophorae Remotiflori Radix (AR; Jeni). Because of confusable publications and the similitude of herb shape, CL and AR have been used as AT in the markets. Methods : We firstly discriminated and confirmed AT, CL and AR through observing the external morphology of original plants. Then, external-internal morphological features of the medicinal herbs were studied. A stereoscope was used to determine macroscopic features of dried herbal medicines and a microscope was conducted to examine internal features with the samples, which were embedded in paraffin and stained. Results : 1. The original plant of CL was discriminated with the stem shape in comparison with others. AT and AR were classified by the leaf position of original plant. 2. In the macroscopic morphological study of medicinal herbs, CL had lumps, which seem like a wart. Also, AT and AR were different in the density of cross section. 3. In the microscopic morphological study of the medicinal herbs, the phloem, fissures and the arrangement of xylem were selected as discriminative criteria for 3 kinds of herbs. With these contents, we suggested the identification keys, including further details. Conclusions : These results, especially identification keys, will be helpful to distinguish 3 kinds of herbs, referred to as a 'Sasam'. Moreover, macroscopic and microscopic methods used in this article would be applicable tools for the discrimination of other herbs.

• The Korea Journal of Herbology
• /
• v.33 no.2
• /
• pp.29-43
• /
• 2018

Objectives : Araliae Continentalis Radix(AC) is a medicinal herb belonging to the drug efficacy group treating musculoskeletal disorders(MSD) with anti-inflammatory, analgesic and antipyretic action. However, due to morphologic and onomastic similarity, adulterants(Angelicae Pubescentis Radix: AP, Gypsophilae Oldhamianae Radix: GO, Levistici Officinalis Radix: LO) have been included or replaced the standard. Methods : Multilateral methods were carried out on the identification of AC and its adulterants. Macroscopic and microscopic characteristics were observed by using stereoscope and microscope. For the comparison of chromatogram pattern, standard compounds were analyzed simultaneously using high performance liquid chromatography. Results : 1. The macroscopic identification of original plants was determined by the phyllotaxis type, the inflorescence type, the leaf margin and the color of flowers. The macroscopic identification of herbal materials was examined by oil spots, the cambium, heteromorphic vascular bundles, and the pholem. 2. For the microscopic identification, the fact whether its xylem ray is proliferated or not was first determined. Then medicinal herbs were secondly divided by cellular inclusions, fiber bundles, the distribution of secretary canals and the shape of cambium. 3. AC and its adulterants showed different chromatographic fingerprints. AC was containing continentalic acid and kaurenoic acid. AP was containing osthole and columbianadin. LO was containing osthole and falcarindiol. None of the compounds were found in GO. Conclusions : This recent identification keys of might be helpful to discriminate the pharmacopoeia standard and its adulterants for the right usage in clinics.

• The Korea Journal of Herbology
• /
• v.32 no.6
• /
• pp.49-54
• /
• 2017

Objectives : Bangki is commonly Sinomeni Caulis et Rhizoma (SC) in Korea. But it often confused with others such as Cocculi Radix (CR), Stephaniae Tetrandrae Radix (SR) and Aristolochiae Fangchi (AR) due to the similarity in herbal names and morphological characteristics. However, because all of these types of Bangi have different healing properties, they need to be differentiated. Methods : A discrimination on external features of original plants and external characteristics of herbal medicines was carried out using visual examination, stereoscope. For the examination of Internal characteristics of herbal medicines, tissues were dyed using fast green FCF, hematoxylin and safranin O, and the features were observed by the microscope. Results : In external morphology of original plants, the original plants of SC and AR were lignum plants and others were herbaceous plants. The leaf blade and the petiole were another discriminative criteria. In external morphology of herbal medicines, SR and AR have powders and others didn't. Also, SC and CR were determined by the dense of the radiation pattern in the cross section. In internal morphology of herbal medicines, SR and AR were distinguished by the dense of Stone cells. Moreover, SC and CR were different in the pattern of medullary ray and vascular bundle. Conclusions : The results above could be used as identification keys of Bangki. Moreover, these identifications might attribute as a fundamental material to further studies like physicochemical pattern analysis and biological reaction.

• The korean journal of orthodontics
• /
• v.31 no.2 s.85
• /
• pp.261-270
• /
• 2001

The purpose of this study was to evaluate the clinical usefulness of plasma arc light which can reduce the curing time dramatically compared by shear bond strengths and failure patterns of the brackets bonded with visible light in direct bracket bonding. Some kinds of brackets were bonded with the Transbond$^{\circledR}$ to the human premolars which were embedded in the resin blocks according to the various conditions. After bonding, the shear bond strength was tested by Instron universal testing machine and in addition , the amount of residual adhesive remaining on the tooth after debonding was measured by the stereoscope and assessed with adhesive remnant index(ARI). The results were as follows : 1. When plasma arc light was used for bonding the brackets, the shear bond strength was clinically sufficient in both metal and ceramic brackets, but resin brackets showed significantly lower bond strength but which was clinically useful. 2. When metal brackets were bonded using visible light, there was no significant difference in shear bond strength due to the light-curing time and the bond strength was clinically sufficient. 3. When the adhesive failure patterns of brackets bonded with plasma arc light were observed by using the adhesive remnant index, the bond failure of the metal and resin bracket occurred more frequently at bracket-adhesive interface but the failure of the ceramic bracket occurred more frequently at enamel-adhesive interface. 4. There was no statistically significant difference of the shear bond strength and adhesive failure pattern between metal bracket bonded for 2 seconds by curing with plasma arc light and 10 seconds by curing with visible light. 6. When metal brackets were bonded using plasma arc light, the shear bond strength decreased as the distance from the light source increased. The above results suggest that plasma arc light can be clinically useful for bonding the brackets without fear of the decrease of the shear bond strength.