• Journal of the korean academy of Pediatric Dentistry
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• v.34 no.1
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• pp.162-168
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• 2007

Impaction of the maxillary central incisor may cause social, esthetic, and functional problems in children. There are various means of treatment for the inverted maxillary central incisor, such as extraction, surgical opening followed by orthodontic traction surgical repositioning or intra-alveolar autotransplantation prior to extraction. In this case, we surgically repositioned the inverted maxillary central incisor to normal semi-erupted position in a 5-year-old boy The developmental stage of the inverted tooth was Nolla's 6.5, which indicates formation of less than one third of the root. After surgical reposition, we did follow-up for 21 months, expecting spontaneous growth Unfortunately, poor prognosis was noted further root was not observed. Such failure seems to originate from possible injury on Hertwig's epithelial root sheath by surgical trauma. We performed surgical repositioning to retain the tooth instead of extraction. However, arrest of root development occurred which is one of the critical complications. In order to increase the success rate of the surgical reposition procedure, minimal surgical trauma is required as well as selection of adequate indication and decision of proper time of treatment considering the stage of root development.

• Journal of Plant Biotechnology
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• v.30 no.2
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• pp.173-177
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• 2003

The effect of IBA and NAA on adventitious root cultures of Panax ginseng C.A. Mater were investigated. Results indicated differences in growth and development of the roots according to 5mg/L IBA and 2mg/L NAA. IBA resulted in a normal root development and a higher growth compared to NAA. The roots formed on NAA-containing media were shorter and thicker than those in IBA, showing a hypertrophy of the root tip. NAA induced more than 1.6 times higher ethylene production compared to IBA, which caused inhibition of the root growth. Under the ventilation, in the other hand, on difference was observed in ethylene concentration and the root growth between IBA and NAA treatments. Under ventilation ethylene production was not detected until 10 days of culture, while detected from the initial stage under on ventilation. The results suggested the importance of ventilation during the culture for the growth and development of ginseng adventitious roots.

• The Journal of Korea Assosiation for Disability and Oral Health
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• v.13 no.1
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• pp.6-13
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• 2017

Premolars show the greatest variation in development and eruption. The present case report identified characteristics of eruption of maxillary premolars with delayed development. Multiple maxillary premolars with delayed development were found to have a palatal ectopic eruption pattern, which was self-corrected through eruption guidance by extraction of preceding primary teeth at the stage of root development when eruption force was maximal. In addition, delayed eruption due to delayed development was substantially improved by eruption guidance. Early erupted premolars with less than 1/3 of root development were induced to have normal root development using stabilizing appliance. The maxillary premolars with delayed development reported in the present study showed no complications such as impaction, space loss by delayed eruption, or insufficient root development.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.27 no.3
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• pp.223-228
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• 1982

Experiments were conducted to study the interrelationships between root development of rice plant and water managements at saline paddy field where has been grown rice plant for 3 years, and to compare the root development between two fields, saline and matured. Under the conditions of non interval and two day interval flooding at saline paddy fields, root systems developed well at surface soil, however, root systems developed well and distributed evenly through surface and sub-soil at saline field where underground drainage was performed, and at matured field. Root developments at field flooded with no interval and with two-day interval were poor as compared with those of saline paddy field of underground drainage and matured field. Regardless of water managements and fields, the ratio of stunted crown roots developed after panicle fromation stage was higher than that developed at early or middle growth stage.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.49 no.2
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• pp.94-99
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• 2004

This study was conducted to determine the effect of salinity on the growth and development of Korean ginseng (Panax ginseng C.A.Meyer) and to evaluate the inorganic ion content in Korean ginseng with different general complete fertilizer (GCF) and NaCI concentrations at two growth stages. The stem height of Korean ginseng treated with different GCF and NaCI concentrations decreased at the higher EC (2.0 dS m$^{-1}$ ), but there were no significant difference in the stem diameter, the leaf length, and the leaf width among different treatments. The root growth increased with the supply of GCF. Especially, the root growth was facilitated two times at 3.0 dS $\textrm{m}^{-1}$ as compared to control. But the root growth more sharply decreased with NaCI treatment than GCF. The $\textrm{K}^{+}$ and $\textrm{Mg}^{2+}$ content in leaves and roots increased with GCF at the early growth stage. At the late growth stage, the $\textrm{K}^{+}$ content in leaves decreased but the $\textrm{Ca}^{2+}$ and $\textrm{Mg}^{2+}$ content increased. The $\textrm{Ca}^{2+}$ and $\textrm{Mg}^{2+}$ content in roots increased but the $\textrm{K}^{+}$ content decreased. The $\textrm{Na}^{+}$ content in Korean ginseng increased sharply with NaCl treatment. The $\textrm{NO}_3^{-}$ content in leaves and $\textrm{NH}_4^{+}$ content in leaves and roots increased as GCF concentration increased. The $\textrm{NO}_3^{-}$ content in leaves, stems, and roots at the late growth stage decreased as NaCl concentration increased. The $\textrm{NH}_4^{+}$ content in leaves and roots decreased significantly at the early growth stage, but it decreased significantly in leaves and stems at the late growth stage. The root activity of Korean ginseng increased with GCF, but decreased as the EC increased with NaCl. The water potential of leaves with GCF showed no significant difference compare to control, but the water potential of leaves treated with NaCl decreased as EC increased.

• Journal of Ginseng Research
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• v.16 no.1
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• pp.31-36
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• 1992

The ultrastructural changes and differentiation mechanism of chromoplasts and leucoplasts from Proplastids in root tip cells of Panax ginseng seedlings were studied with transmission electron microscope. Initial cells have so many proplastids with a few osmiophilic droplets and a lot of mitochon dria at early stage of germination, therefore electron density of cytoplasm is generally higher than that of the other cells just like periblem, plerome and root cap. Proplastids are observed in the initial cells, but only leucoplasts appeared in the central root cap cells. Because root cap cells are derived ultimately from initial cells, the cell organelles in the root cap cells are directly related by those of initial cells. This result postulates that leucoplast is diferentiated from proplastid, and this is the same with other's concepts. On the contrary, the precise observations of chromoplast with crystalline inclusions in the peripheral root cap cells can conclude the direct pathway of chromoplast development from proplastid. Because of the differences of these result from those of other experiments, new scheme of plastid development, direct differentiation of chromoplast from proplastid, can be postulated. And this is the originality of this research on the differentiation of plastids.

• Journal of the korean academy of Pediatric Dentistry
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• v.29 no.4
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• pp.607-617
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• 2002

The purposes of this study were to evaluate the timing of tooth calcification and the change of tooth position with tooth developmental stage on the mandibular teeth. Seven hundred seventy two children(male:446, female:326), 3 to 12 years of age were examined radiographically with panoramic film. Dental development was determined by inspecting radiographs and assigning a rating according to consecutive stages defined by Moorrees, and tooth cusp position and root terminus position were measured from the lower border of mandibular body and calculated the position index to evaluate the movement of tooth with developmental stage. The results were as follows. 1. There were no significant differences between boys and girls in the timing of calcification until crown completion, but timing of calcification tend to be faster in girls than in boys after root initiation stage. 2. In terms of mean age, crown completion of central incisor in boys and girls occurred at the age of 3.71, 4.05 years, at 4.44, 4.60 years for the lateral incisor, at 5.35, 5.11 years for the canine, at 6.62, 6.36 years for the first premolar, at 7.36, 7.17 years of second premolar, at 3.51, 3.69 years of first molar, and at 7.90, 7.64 years for the second molar respectively. Apex 1/2 closed stage of central incisor occurred at the age of 8.70 in boys, 8.18 in girls, at 9.55, 8.99 years for the lateral incisor, at 12.48, 11.60 years for the canine, at 12.30, 12.01 years for the first premolar, at 12.19, 12.26 years of second premolar, at 9.12, 8.87 years of first molar, and at 12.59, 12.45 years for the second molar respectively. 3. There was no noticeable movement of cusp tip until crown completion (Crc), but showed rapid movement toward occlusion plane after root initiation(Ri) and again maintain stable position after root completion stage(Rc). 4. Root terminus position was stable until root 1/4 formation stage(R1/4), followed by rapid movement toward occlusal plane and was stable again after root 3/4 formation stage(R3/4). 5. Developmental stage at the time of alveolar bone penetration by cusp tip varied with each of the permanent teeth. 6. Canine tooth follicle was at the lowest position in the mandibular body during the early stage of calcification, followed by second premolar, first premolar, lateral incisor, second molar, first molar and central incisor in order.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.43 no.2
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• pp.77-82
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• 1998

Aerenchyma development in rice (Oryza sativa L.) roots is quite important for adaptation to waterlogged or reduced soil conditions. Anatomical observations were carried out to clarify the development of schizogenous and lysigenous aerenchyma in elongating crown roots of rice. The crown roots of 3rd and 4th phytomer were taken from rice plants of the 8th leaf stage grown by hydroponic culture. The schizogenous intercellular spaces in the cortex of crown root tip were observed using a light microscope with semi ultra-thin sections and the lysigenous aerenchyma in mature tissue of crown root were observed using a cryo scanning electron microscope (cryo-SEM) with freezing fracture method. The schizogenous intercellular spaces in the root tip exist obviously in the middle portion of cortical cell layers close to the root-root cap junction, but not in root cap, stele and outer cell layers of cortex. The air spaces were formed at the junction of four neighbouring cells of inner cortex in the transverse sections, and between longitudinal cell layer connected along the root axis. Although many of those spaces were filled with liquid, some spaces seem to exist as air spaces. The lysigenous aerenchyma in the cortex, which hardly filled with liquid, emerged at 3-4 cm segment from the root tip and increased toward the basal region of root axis. The developing process of lysigenous aerenchyma was primarily separation of a radial row of cells caused by the shrinking and collapsing of cortical cells and then formation of septa along the radial cell rows by the fusion of cell wall with each other. These results suggest that the schizogenous and lysigenous aerenchyma playa role as a passage for the movement of oxygen into the root tip region where oxygen is required for respiration.

• Plant Disease and Agriculture
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• v.5 no.2
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• pp.77-83
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• 1999

In 1997 surveys 82 out of 180 crucifer fields were infected with clubroot disease in a range of 1-100% of diseased plants and among crucifier crops Chinese cabbage was the most severe, In cropping systems Chinese cabbage-monocropping of Chinese cabbage-radish were found to be most common in major Chinese cabbage production areas. Welsh onion squash or paddy rice were also planted between cropping of Chinese cabbage. Paddy fields converted to upland were lowered in incidence of clubroot disease and fields with loam to silty loam soil were more severe in disease than those with sandy soil. Soil pH and organic contents were nor related to clubroot disease severity. Soil fauua such as total fungi bacteria actinomyces Pseudomonads and Bascillus were not correlated with severity of the disease. Root rall development on Chinese cabbage seedlings was initifially observed under a microscope 13 days after inoculation with Plasmodiophora brassicae but 18 days by naked eyes after inoculation. Root galls were formed mostly around collar roots and gradually spread to main root lateral roots and secondary root branches. Root galls started to enlarge greatly in size and weight from 23 days after inoculation. Chinese cabbage plants at mid-growth stage with root gall development were reduced to 1/2 of that of healthy plants in number of leaves 1/4-1/5 in above ground fresh weight 1/6 in root length but increased to 3 times in diameter of collar root. Diseased plants had little root hairs. Diseased Chinese cabbage plants at harvest were reduced by 9,1-11.8% in head weight compared to healthy plants a positive correlation was observed between root and head weight but those relationships were rot found in the diseased plants.

• Plant Resources
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• v.6 no.3
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• pp.183-187
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• 2003

Two kinds of Angelica belong to Umbelliferae collected, the one is Angelica gigas that is inhabitant in Korea and the other is Angelica acutiloba that is indigenous in Japan at the field of Snyder Research and Extension Farm Rutgers University, New Jersey and was analyszed by GC and GC/MS. The composition of the essential oil of the different aerial parts of the Angelica has been studied. The oil yields obtained upon hydrodistillation were 0.18% (v/w) in Korean Angelica and 0.44% (v/w) in Japanese Angelica on dry root weight basis. By the growing stage in the Rutgers greenhouse condition, leaf and root of essential oil content a little decreased on 9 months later than 4 months later except for Angelica gigas leaf. Both of Angelica showed that amounts of essential oil content presented in order of leaf > petiole > root according to different plant part. The analysis of the essential oil from Angelica root led to the identification of 14 constituents totaling 64% in Korean Angelica and 13 constituents totaling 68% in Japanese Angelica. The major constituents of the Angelica root essential oil were ligustilide (47 %) and gamma terpi (14 %) in Korean Angelica, and alpha pinei (32 %) and nonane (25 %) in Japanese Angelica