• Korean Journal of Child Studies
• /
• v.32 no.1
• /
• pp.103-123
• /
• 2011

The purpose of this study was to investigate infants' individual attempts at interaction with their teachers in the two-year-old class curriculum of a child care center. To achieve this aim, this study analyzed both the types of interactions that infants attempted with their teachers, as well as the underlying message contained in infants' attempts at of interacting. This study used the complete participation observation methodology following an ethnographic approach, a research method which can help us see the whole picture by tracing the main causes and connections. The participants in this study were 13 infants and their teachers in 2 two-year-old classes (Hope and Love) of the Vision Child Care Center located in G city. The researcher, who was also a Hope-class teacher, ad as an observer, and the Love-class teacher acted as an assistant observer. Participant observation was made everyday except the days when field trips and group activities wewe planned, from october 2009 to January 2010. A variety of methods were used to collect materials, such as participant observation, in-depth interviews and collection of documents.

• Development and Reproduction
• /
• v.16 no.4
• /
• pp.385-388
• /
• 2012

The sex ratio (F:M) in the same population of oyster, Crassostrea gigas at the commencement of the study (2007) was 1:1.0, but changed to 1:2.8 by the end of the study (2008). The sex reversal rate in two-year-old oysters was 40.2%. Specifically, female to male sex reversal rate was 66.1%, which is higher than the male to female sex reversal rate of 21.1%. The sex reversal pattern of C. gigas appears to go from male ${\Rightarrow}$ female ${\Rightarrow}$ male, and as such is determined to be rhythmical hermaphroditism.

• Journal of Korean Society of Forest Science
• /
• v.111 no.3
• /
• pp.394-404
• /
• 2022

This study was conducted to optimize the amount of drip irrigation for Prunus×yedoensis Matsum., one of the major medium-sized landscaping trees used mainly for streetscapes and as ornamentals. The experiment was conducted in a container nursery, where we assessed the growth and physiological characteristics of 4- and 8-year-old seedlings watered at different rates (x) by a drip irrigation system. The relative growth rates (based on height and root collar diameter (RCD) measurements) were highest at 288 and 416 L/year/tree for the 4- and 8-year-old containerized seedlings, respectively. These age and treatment combinations also produced significantly different dry weight and seedling quality index values, indicating good growth. The two age groups had significantly different total root lengths, root diameters, and root volumes under these respective irrigation treatments. In addition, the 4-year-old containerized seedlings irrigated at 288 L/year/tree and the 8-year-old containerized seedlings irrigated at 416 L/year/tree had the highest activations in their chlorophyll contents. Overall, the results (differences in irrigation amounts affect the seedlings morphological relative growth, biomass growth, seedling quality, and physiological reaction) indicate that the optimal irrigation amounts for container-grown Prunus×yedoensis are 288 L/year/tree for 4-year-old (RCD class, 3cm) and 416 L/year/tree for 8-year-old (RCD class, 7 cm) containerized seedlings.

• Journal of Forest and Environmental Science
• /
• v.9 no.1
• /
• pp.1-9
• /
• 1993

In the fall of 1992, growth characteristics and cone-bearing behaviour of crown top shoots were investigated on Pin us koraiensis trees, belonging to age class VII and IV, in the School Forests, College of Forestry, Kangwon National University to obtain basic information for the design of Korean pine cone harvesting machine. The results were summarized as follows. 1. The length of terminal main shoots and lateral shoots of the trees in age class IV was 27~56cm and 18~47cm, respectively, both of which were significantly higher than those of the trees in age class VII. 2. There was no significant difference between two age classes in the branching angle ($24{\sim}89^{\circ}$) of lateral shoots and in the diameter (10~30mm) of two-year-old main shoots. However, one-year-old terminal main shoots of age class IV showed the higher diameter (9~18mm) than those of age class VII. 3. Mean cone number per tree was 5, and mean fresh weight of cone was 272g. No significant difference was found in these traits between both age classes. 4. Cones, on an average, hung on the two-year-old main shoots 15cm above the basal ends in age class VII and 33cm above in age class IV. Both lengths are equivalent to one half and four fifths of the shoots, respectively. 5. The fresh weight range of crown-top shoots containing cones was 1.0~7.4kg.

• Korean Journal of Child Studies
• /
• v.22 no.4
• /
• pp.201-212
• /
• 2001

The purpose of this study was to analyze toddlers' verbal and nonverbal interaction with their peers and caregivers according to the class size of child care centers in Seoul. The subjects of this study were 20, two-year-old(M=32.5 month) toddlers with peers and caregivers from child care centers in different class sizes, but with same caregiver-toddler ratio. Verbal and nonverbal interactions were videotaped during one hour indoor free play per child in the center. According to the class size, the results were as follows : 1) Toddlers in the small class played more cooperatively with peers, and uttered more regulative or directive words than those in the large class. 2) Toddlers in the large class were more aggressive than those in the small class. 3) Caregivers in small class expressed more empathetic behaviors to a toddler than those in large class.

• Korean Journal of Child Studies
• /
• v.23 no.1
• /
• pp.121-137
• /
• 2002

This study examined the vocabulary competence of institutionalized and home-reared 6- and 7-year-old children with the use of the Revised Picture Vocabulary Test(Dunn & Dunn, 1981; Korean version, Kim et al., 1995), administered to 113 institutionalized children and 124 middle class home-reared children. Results indicated that the vocabulary competence of institutionalized children was inferior to that of home-reared children. Children who had lived in an institution for two years or more scored lower than those who had been institutionalized for a shorter time. 7-year-olds scored higher than 6-year-olds, regardless of institutionalization. Home-reared girls scored higher than home-reared boys, but there was no sex difference between institutionalized children. These findings suggest that efforts should be directed toward improving the linguistic environment of institutionalized children.

• The korean journal of orthodontics
• /
• v.45 no.6
• /
• pp.322-332
• /
• 2015

A 12-year-old girl was referred to our clinic for evaluation of an unaesthetic dental appearance. All permanent teeth were erupted, while the deciduous maxillary right canine was retained. Cone-beam computed tomography revealed a complete transposition of the maxillary left canine and first premolar involving both the crowns and the roots. Initial cephalometric analysis showed a skeletal Class III pattern, with a slight maxillary retrusion and a compensated proclination of the upper incisors. The patient's teeth were considered to be in the correct position; therefore, we decided to attempt treatment by correcting the transposition and using only orthodontic compensation of the skeletal Class III malocclusion. After 25 months of active orthodontic treatment, the patient had a Class I molar and canine relationship on both sides, with ideal overbite and overjet values. Her profile was improved, her lips were competent, and cephalometric evaluation showed acceptable maxillary and mandibular incisor inclinations. The final panoramic radiograph showed that good root parallelism was achieved. Two-year follow-up intraoral photography showed stable results.

• The Journal of the Korean dental association
• /
• v.48 no.11
• /
• pp.819-828
• /
• 2010

Activator is a removable functional appliance used for correcting the skeletal Class II malocclusion in children with the mandibular deficiency. Berlin standard activator modified from Andresen activator has following characters; do not cover the palatal surface for tongue space, relief on lingual surface of mandibular incisors and resin capping 1/3-1/2 of crown height on mandibular incisors for preventing labioversion of mandibular incisors, L-hook between maxillary lateral incisor and canine for anterior high pull headgear, relief on mandibular posterior bite block for differential eruption of posterior teeth. Two cases presented here had a mandibular deficiency and slight maxillary protrusion. First case (an 11-year-old girl) treated with Berlin standard activator and anterior high pull headgear for 13 months followed by fixed orthodontic appliance for another 29 months. Second case (a 12-year-old boy) treated with Berlin standard activator for 6 months followed by fixed appliance for another 24 months. Treatment results showed a significant improvement in sagittal skeletal and occlusal relationship without premolar extraction. Mandibular condyles were concentric in TMJ [ossa, and masticatory muscle activities were normalized after treatment. In the retention period facial harmony and occlusal stability was maintained.

• The Journal of the Korean dental association
• /
• v.15 no.2
• /
• pp.107-110
• /
• 1977

Class I malocclusion is essentially a dental dysplasia. Rotations, individual tooth malpositions, missing teeth, tooth size discrepancies, etc., fall under this classification. There are two types of class I malocclusions. One is identified by and insufficient denture base to accommodate the teeth; the other has more denture base than tooth material, creating spaces in the arch. The tooth material-to denture base discrepancies may be slight, calling for only a little increase in arch length for alignment and the correction of minor rotations. Discrepancies may also be great, in which case it becomes necessary to reduce tooth material by extraction, so as to make the tooth material more in proportion to the size of the denture base. The author had attempted orthodontic treatment of a class I malocclusion case of 13-year old boy in which high canines and impacted mandibular second premolars were involved. The author obtained good results.

• Journal of dental hygiene science
• /
• v.20 no.2
• /
• pp.118-124
• /
• 2020

The purpose of this comparison of case reports is to introduce the results of the application of new devices for the management of growing Class III malocclusions in children. Two 8-year-old boys had a chief complaint of anterior crossbite. Anterior crossbite correction using a tandem traction bow appliance (TTBA) or a Carriere Motion 3D Class III appliance with a Transforce appliance was planned. By comparing cephalometric radiographs before and after treatment, changes in skeletal growth and incisor inclination to the Frankfort horizontal (FH) plane could be measured. Both devices increased SNA and ANB angles, N-I Pg-A, U1 to SN, and U1 to FH. Both appliances improved facial features and resolution of anterior crossbite. The TTBA and Carriere Motion 3D Class III appliance had similar effects when applied as early treatment for growing mesio-occlusions and anterior crossbite in two boys. However, long-term outcome assessments and well-designed comparative studies are still required.