• The Korean Journal of Archival Studies
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• no.79
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• pp.389-442
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• 2024

In order to establish a corporate records schedule, this study identifies the types of records and retention periods specified by domestic laws for companies to retain, reviews the significance and characteristics of the results, and proposes establishing a corporate records schedule. To this end, this study identified the company's management activities, prepared a record survey for legal analysis, and extracted the record types and retention periods necessary for the company's management activities through a review of various laws. Next, this study looked at the meaning and characteristics of the types of records and retention periods required by companies. Finally, based on the analysis results, a method for establishing a corporate record processing schedule was proposed.

• The korean journal of orthodontics
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• v.21 no.3
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• pp.635-656
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• 1991

It was the aim of this investigation to evaluate some histologic aspect of rat pulp tissue after it had been compromised by an experimental orthodontic force. Experimental animals of thirty five Spraque-Dawley rats were employed. The first upper molars had been successively mesial moved (initial load 100 gr.) with a closed coil spring during 21 days. The experimental periods were set on immediate, 1 day, 1 week, 2 weeks, 3 weeks, 4 weeks following retention time. On each experimental period, the rats were killed and prepared for the light microscopy. After prepared with H/E stain and Gomori's one-step trichrome stain, the specimens were analyzed with evaluation criteria which were adopted in this study. The result may be summarized as follows; 1. The main pulp changes due to experimental orthodontic force included vacuolization of odontoblastic layer, circulation disturbance, root resorption, reduced pulp collagenous fiber density and mean cell count of pulp fibroblast in the immediate group. 2. The pulp tissue changes were revealed reversible because the relieved pulp tissues from experimental orthodontic force were recovered rapidly in each evaluation criteria during retention periods. 3. Compared with normal control group, pulp collagenous fiber density were decreased in immediated group (p < 0.01), but increased in each retention groups. These seem to suggest that the pulp tissues were aged after experimental orthodontic force conditions. 4. Compared with normal control group, mean cell counts of pulp fibroblasts were decreased in immediate group (p < 0.05), but increased continuous in each retention groups. These seem to indicate that the pulp tissues were highly regenerative after experimental orthodontic force conditions. 5. Compared with normal control group, root resorptions occurred in all immediate specimens (p < 0.01) and they were healed in each retention periods, but often observed in 4 weeks retention group. These seem to indicate that root resorptions were recovered slowly after experimental orthodontic force conditions.

• The korean journal of orthodontics
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• v.49 no.4
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• pp.235-245
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• 2019

Objective: This study examined bone microstructure restoration after rapid maxillary expansion (RME) with and without corticotomy over multiple retention periods. Methods: Eighteen male Dorper sheep were randomly distributed into three groups (n = 6 each group): group 1, RME with corticotomy on the buccal and palatal sides; group 2, conventional RME treatment; and group 3, no treatment. Post-RME, trabecular bone microstructure and new bone formation were evaluated by using microcomputed tomography (microCT) and histomorphometry after a 4- or 12-week retention period. Intergroup differences in bone quality and bone remodeling were analyzed by using two-way analysis of variance with Bonferroni post-hoc test. Results: The bone volume fraction (bone volume [BV]/total volume [TV]) values relative to the control in groups 1 and 2 were 54.40% to 69.88% after the 4-week retention period and returned to approximately 80% after the 12-week retention period. The pooled BV/TV values of the banded teeth in groups 1 and 2 were significantly lower than those of the control after the 4-week retention period (p < 0.05). However, after the 12-week retention period, the pooled BV/TV values in group 2 were significantly lower than those in groups 1 and 3 (p < 0.05). Histomorphological analysis showed that the new bone formation area in group 1 was approximately two to three times of those in group 2 and control. Conclusions: Corticotomy significantly enhanced the restoration of bone quality after the retention periods for banded teeth. This benefit might result from the increased new bone formation after corticotomy.

• Journal of Nutrition and Health
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• v.34 no.1
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• pp.54-61
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• 2001

The Ca and P balance studies were carried out with two different diets varying Ca levels : the current Korean RDA level(normal Ca diet) and the high level (High Ca diet) which was determined by adding 2SD to mean Ca intake of all subjects. The subjects were sever healthy adult woman, aged from 25 to 32 years old. The metabolic studies were conducted for two weeks with a days recess in between : during the fist week with normal Ca diet and during the second week with high Ca diet. The composition of nutrients excepting Ca of both diets was similar to subjects usual intake. The result were summarized as follows: Mean daily Ca intake was 728.8mg from norma Ca diet and 945.5mg from high Ca diet. Fecal excretion of Ca increased significantly(p<0.05) on high Ca diet, but urinary excretion of Ca did not show any differences between the two diet periods. There were also no significant differences in Ca retention between the two diet periods but it tended to be greater during high Ca diet period: 112.1mg/day during normal Ca diet period vs 208.2mg/day during high Ca diet period. Mean apparent Ca absorption was 41.2% on normal Ca diet and 42.1% on high Ca diet, indicating it was not affected by high Ca intake level used in this study. On the contrary, P retention was significantly increased up to 109.4mg/day with high Ca diet as compared to- 41mg/day with normal Ca diet. There were no significant differences in fecal and urinary excretion of P but those to be lower during high Ca diet period. The above results showed that higher Ca intake more than current RDA(700mg/day), in the level of 945.5mg/day, could increase Ca retention through Ca absorption comparable to the rate appeared on RDA level intake. P retention was also improved by high Ca intake. Therefore, higher Ca intake than the current RDA level seemed to produce favorable effects on bone health in adult women. However, the current RDA level seemed to be relatively appropriate, considering the results that all the subjects but one maintained positive Ca balance with normal Ca diet. (Korean J Nutrition 34(1):54-61, 2001)

• Journal of Korean Society of Archives and Records Management
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• v.12 no.2
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• pp.117-142
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• 2012

This study analyzes the relevance of retention period assigned for each unit task based on the table of records management standards that has been used in schools around the country since January 2011. Retention period, which used to be appropriated on the basis of a record file in the classification scheme, has been re-appropriated on the basis of unit tasks after the table of records management standards have been introduced. However, the new retention period of school records directly apply the 7 retention periods defined for public institutions according to Public Records Management Act. Therefore, this study attempts to analyze the relevance of retention period for school records appropriated for unit task from various angles regarding laws, indexes, survey results, overseas cases.

• Journal of The Korean Association For Science Education
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• v.32 no.6
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• pp.1027-1038
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• 2012

We investigated the effect of Science Writing Heuristic (SWH) on elementary students' concept formation and their retention. Also we explored the interaction effect of those with scientific attitudes. We developed mirrors/lenses lessons incorporating SWH. An experimental group of fifth grade students (n=25) had been instructed with SWH lessons for six periods while a control group (n=25) taught according to the normal science lessons based on the Korean national curriculum using teacher's guides published by the Ministry of Education. Results of pre- and post-test of understanding the concept of mirrors and lenses showed a positive impact of SWH on both male and female students. However, the retention effect after post-test revealed that SWH only had an effect on female students' scientific attitudes. SWH, therefore, could be an effective teaching approach especially on concept formation, retention effects by fostering female students' scientific attitudes.

• Journal of Veterinary Clinics
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• v.9 no.1
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• pp.311-316
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• 1992

Four retention sutures were used to correct the vaginal prolapse in a dairy cow. The methods used were two modified Caslick operation of vulva using absorbable(catgut chromic) and nonabsorbable(supramid) materials, and a modified mattress closure and a modified Buhner method of vulva using trocar and wire insulated by vinyl. The lasting periods for retention of bovine vaginal prolapse by the suture methods described above, were 12 days, 49 days, 39 days and 62 days respectively.

• The korean journal of orthodontics
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• v.33 no.2 s.97
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• pp.103-111
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• 2003

The Purpose of this study was to evaluate the effect of occlusion on the mechanical strength of periodontal fibers during retention periods after experimental tooth movement. In the Sprague-Dawley male rats weighing 200g or more, the ntraoral elastics were inserted into the both right and left interproximal space between upper first and second molars for tooth movement. kiter 4 days later, the left lower first, second, and third molars were extracted for differentiating the non-occlusal side from the occlusal side in the same mouth. At the same time the elastics were removed and then light cured resin was Placed in the space between upper first and second molars following undercut was made for retention bilaterally. From the beginning of retention, 7 rats were sacrificed at 0, 4, 8, 12, 16, 20 days respectively. For evaluating of magnitude on the mechanical strength of periodontal tissue, the maximal shear load of the upper first molars were measured bilateraly during extraction using Instron Universal Testing Machine. The results of this study were obtained as follows : 1. In the occlusal side, the maximal shear load was increased from no retention to retention 20 days group as time was going and statistically difference was shown from retention 12 days group (p<0.05). 2. In the non-occlusal side, the maximal shear load was increased slightly from no retention to 20 days group as time was going but there was no statistically difference (p>0.05). 3. The result compared with the maximal shear load between occlusal and nonocclusal side showed no statistically difference until retention 8 day group (p>0.05), but showed statistically difference from retention 12 day to 20day group (P<0.05). These results show that occlusion had an effect on mechanical strength of the periodontal fibers during retention periods after experimental tooth movement; therefore, it is suggested that occlusion should be considered while the retainer types and retention period are planned.

• Journal of the Korean BIBLIA Society for library and Information Science
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• v.31 no.2
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• pp.139-160
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• 2020

Since the Public Records Management Act was enacted in 2007, the administrative information system has already been included in the electronic records production system, and dataset has been subject to record management as a type of electronic records. With the recent revision of the enforcement decree, dataset records management has been enacted. This study analyzes business units related to administrative information systems of public institutions and examines the current status of retention periods estimation. For this purpose, we collected 36 records classification systems from 49 public institutions among the direct management agencies of the National Archives and disaster management agencies. And we discriminated 824 business units related to administrative information system and divided into large and small groups according to types. We also compared the retention period estimation of records. The problems and improvement plans of this study are expected to be used as basic data in preparing the standard of administrative dataset management in the future.

• Journal of the Korean School Mathematics Society
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• v.6 no.1
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• pp.45-63
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• 2003

This study is a research about the effect on achievement, retention and attitude of learning descriptive statistics with the computer software. For this study, 60 students are randomly divided two groups, one is an experimental group using software, the other one is a control group using lecture type of learning statistics. For the analysis, both groups are divided three subgroups according to mathematical ability. Also the topic "descriptive statistics" is divided by 5 subtopics. The test is divided three parts(computation, concept and application) according to knowledge type. The attitude toward statistics is investgated with questionaire and interview with both groups. The achievement test is taken after 8 class periods. The retention test were administered together six weeks after achievement test. The experimental group achieved significantly better than in concept type while the control group performed significantly better than the experimental group in computation type. With respect to the attitude toward statistics, lower ability students may have been negatively affected by the use of software.