• Journal of the Society of Cosmetic Scientists of Korea
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• v.26 no.1
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• pp.213-232
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• 2000

Cetostearyl alcohol has been incorporated into cosmetic or pharmaceutial emulsions to give them an appropriate consistency and a long term stability. It is well known that cetostearyl alcohol forms a gel phase with a nonionic surfactant in an aqueous system, and the properties of the gel phase depend on several factors such as the ratio of fatty alcohols. The aim of the present Paper is to investigate the effect of the structural difference of the lipophilic part of surfactants on the stability of the gel phase in the nonionic surfactant / cetostearyl alcohol / water ternary systems using differential scanning calorimeter. It is concluded that the gel phase formed by the surfactant having the bended alkyl chain is more unstable than that formed by the case of the straight alkyl chain, and we discussed the reason why the former is more unstable after long term storage by means of the measurements of the ${\Delta}$H.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• v.41 no.3
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• pp.156-164
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• 2015

Bilateral sagittal split ramus osteotomy is considered a standard technique in mandibular orthognathic surgeries to reduce unexpected bilateral stress in the temporomandibular joints. Unilateral sagittal split ramus osteotomy (USSO) was recently introduced to correct facial asymmetry caused by asymmetric mandibular prognathism and has shown favorable outcomes. If unilateral surgery could guarantee long-term postoperative stability as well as favorable results, operation time and the incidence of postoperative complications could be reduced compared to those in bilateral surgery. This report highlights three consecutive cases with long-term follow-up in which USSO was used to correct asymmetric mandibular prognathism. Long-term postoperative changes in the condylar contour and ramus and condylar head length were analyzed using routine radiography and computed tomography. In addition, prior USSO studies were reviewed to outline clear criteria for applying this technique. In conclusion, patients showing functional-type asymmetry with predicted unilateral mandibular movement of less than 7 mm can be considered suitable candidates for USSO-based correction of asymmetric mandibular prognathism with or without maxillary arch surgeries.

• Journal of the Korean Geotechnical Society
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• v.37 no.8
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• pp.25-35
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• 2021

Recently, the ground anchor method is commonly applied with nail and rock bolt to secure the stability of slopes and structures in Korea. Among them, permanent anchor which is used for long-term stability should secure bearing capacity and durability during the period of use. However, according to recent studies, phenomenon such as deformation to slope and the reduction of residual tensile load over time have been reported along the long-term behavior of the anchors. These problems of reducing residual tensile load are expected to increase in the future, which will inevitably lead to problems such as increasing maintenance costs. In this study, we identified the factors that affect the tensile load of permanent anchor from a literature study on the domestic and foreign, and investigated the prior studies that analyzed previously conducted load cell monitoring data. Afterwards, using this as basic data, the load cell measurement data collected at the actual site were analyzed to identify the tensile load reduction status of anchors, and the long-term load reduction characteristics were analyzed. Finally, by aggregating the preceding results, proposed a technique to predict the long-term load reduction characteristics of permanent anchors through short-term data to around 100 days after installation.

• Communications for Statistical Applications and Methods
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• v.18 no.4
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• pp.495-505
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• 2011

This study performs statistical tests for stability of a long-run relationship in the telecommunication market system by identifying the time path of a recursively estimated cointegration parameter. A dummy variable is used to recover stability for the period that the hypothesis of stable cointegration is rejected, and then a proper cointegrating relation is derived. A dummy variable appears to reflect the structural change in the cointegrating relation according to the analytical results for the error correction term.

• Proceedings of the KIEE Conference
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• 1987.07a
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• pp.662-666
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• 1987

• Proceedings of the Korean Radioactive Waste Society Conference
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• 2016.10a
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• pp.231-232
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• 2016

• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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• v.20 no.4
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• pp.429-453
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• 2022

Numerical modeling and scenario composition are needed to characterize the geological environment of the disposal site and analyze the long-term evolution of natural barriers. In this study, processes and features of the hydro-mechanical behavior of natural barriers were categorized and represented using the interrelation matrix proposed by SKB and Posiva. A hydro-mechanical coupled model was evaluated for analyzing stress field changes and fracture zone re-activation. The processes corresponding to long-term evolution and the hydro-mechanical mechanisms that may accompany critical processes were identified. Consequently, practical numerical methods could be considered for these geological engineering issues. A case study using a numerical method for the stability analysis of an underground disposal system was performed. Critical stress distribution regime problems were analyzed numerically by considering the strata's movement. Another case focused on the equivalent continuum domain composition under the upscaling process in fractured rocks. Numerical methods and case studies were reviewed, confirming that an appropriate and optimized modeling technique is essential for studying the stress state and geological history of the Korean Peninsula. Considering the environments of potential disposal sites in Korea, selecting the optimal application method that effectively simulates fractured rocks should be prioritized.

• Herbal Formula Science
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• v.19 no.1
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• pp.183-194
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• 2011

Objectives : To estimate the shelf-life by long-term storage test of Pyungwi-san. Methods : Experiments were conducted to evaluate the stability such as the selected physicochemical, heavy metal, microbilogical experiment under an acceleration test and long-term storage test of Pyungwi-san in different storage under room temperature, refrigeration and freezing. Futhermore, HPLC analysis was performed for the determinations of glycyrrhizin in the Pyungwi-san on an Inertsil ODS-3 column(250 mm ${\times}$ 4.6 mm, 5 um) using solvent 35% acetonitrile include 0.05% phosphoric acid at 254 nm. The flow rate was 1.0 mL/min. Results : The significant change was not showed in pH, heavy metal, microbiological, identification test and quantitative analysis based on acceleration test and long-term storage test. Retention time of glycyrrhizin in HPLC chromatogram was about 16.065 min and calibration curve showed good linearity($R^2$ = 0.9999). The contents of glycyrrhizin in acceleration test and long-term storage test were 0.068~0.076 mg/mL and 0.066~0.077 mg/mL, respectively. Shelf-lifes of room temperature, refrigeration and freezing by long-term storage test were predicted 41, 24 and 34 months, respectively. Conclusions : The suggested shelf-life would be helpful on the storage and distribution of herbal medicine.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.20 no.10
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• pp.395-405
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• 2019

Korea is undergoing a change in its population structure, due to economic development, falling birth rates and the development of health care. As the population ages, the number of elderly people who have difficulty in daily life such as dementia and paralysis increases every day. The growth of nuclear families and the increased participation of women in society make it difficult to take care of elderly people who need long-term care at home. As the social problems resulting from this have emerged as serious problems, the government enacted and implemented the Long Term Care Insurance Act to improve the quality of life for the elderly subject to long-term care and to ease the burden of family support in order to solve such problems. Therefore, the present study explores ways to improve legal and institutional aspects, and seek mental and psychological measures for the stability of old life as well as the physical health of welfare.

• Research in Community and Public Health Nursing
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• v.30 no.3
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• pp.295-306
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• 2019

Purpose: There has been a growing recognition that person-centered care enhances the quality of life of nursing home residents with dementia. This study was conducted to develop a person-centered dementia care online education program for direct care staff in long-term care facilities. Methods: Delphi method with expert group was used to validate contents. We developed 61 draft items based on literature review. Twenty experts participated in consecutive three round surveys including 5-point Likert scale questions and open-ended questions. Based on experts' opinions, the content validity ratio for content validity and the coefficient of variation for stability were calculated. Results: Three-round Delphi surveys and additional feedback from the expert panel established a consensus of core contents: 1) dementia (7 categories), 2) person-centered care (6 categories), 3) communication (8 categories), and 4) behavioral and psychological symptoms of dementia (6 categories). Specific sub-categories in each category were differentiated according to the job qualifications (65 sub-categories for registered nurses, 64 sub-categories for nursing aids, and 41 sub-categories for personal care workers). Conclusion: This delphi study identified person-centered dementia education curricula, in which the person-centered approach should be a key policy priority in Korean long-term care system. Now it is urgently needed to develop education programs utilizing online platforms that enable efficient and continuous learning for long-term care staff, which can contribute to behavior changes in the person-centered dementia care approach and improvement of care quality in long-term care facilities.