• Journal of the Korean Society of Food Science and Nutrition
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• v.32 no.2
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• pp.175-180
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• 2003

Effect of the addition of maltitol to Korean rice cake (Karedduk) on its retrogradation was examined. Degree of retrogradation was also examined in terms of recrystallinity of starch and color change with a differential scanning calorimeter. As a result, retrogradation was suppressed by the increasing addition of maltitol. In particular, enthalpy showed a tendency to decrease at $25^{\circ}C$ rather than at 4$^{\circ}C$ during 4 days. In the gelatinization properties using DSC, onset temperature (To) was shown to increase slightly according to storage time. Maximum peak temperature (Tp) was shown to decrease by the addition of maltitol during 4 days. Melting enthalpy was decreased at $25^{\circ}C$ and 4$^{\circ}C$ by the addition of maltitol. The analysis X-ray diffraction also revealed that retrogradation of the Korean rice cake was suppressed by the addition of maltitol because crystalline region did not appear. The addition of maltitol into the Korean rice cake was found to result in an increase of its qualify or color stability.

• Elastomers and Composites
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• v.44 no.3
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• pp.269-273
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• 2009

A study on the life-time expectation of a CR-modified NR rubber composite through the change of thermal degradation characteristics was performed using both isothermal thermogravimetric analysis (TGA) and thermomechanical analysis (TMA). Master curves at reference temperature of $90^{\circ}C$ could be obtained with shift factor $a_T$, which was determined empirically using Time-Temperature Superposition Principle (TTSP). Activation energies could be calculated from the slope of Arrhenius plot of shift factor and showed similar values of $E_{a,TGA}$= 41.2 and $E_{a,TMA}$= 54.5 kJ/mol, respectively. It was considered from the results that chemical degradation resulting weight loss of the sample might be closely related to a physical degradation such as the dimensional change of the sample.

• Composites Research
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• v.21 no.6
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• pp.23-30
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• 2008

In this paper, the effect of the natural aging on the strength distribution and structural service life of a Filament Wound (FW) composite pressure vessel was studied. The fiber failure strain, which is varied significantly, was considered as the design random variable and the strength analysis was carried out by probabilistic numerical approach. The progressive failure analysis technique and the First Order Reliability Method (FORM) were embedded in this numerical model. As the calculation results, the probability of failure was obtained for each aging time steps and it is found that the strength degradation in FW composite pressure vessel, due to the natural aging, appears within 10 year-aging-time. As an example of the life prediction under natural aging using arbitrary laminated model, the service lifetime of 13 years was predicted based on the probability of failure of 2.5% and the design pressure of 3,250 psi.

• The Journal of the Korea Contents Association
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• v.20 no.9
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• pp.494-502
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• 2020

This study is a phenomenological study conducted to gain a deeper understanding of the positive psychological capital experience of the elderly women who participated in the long-term movement. In Korea, women are eight years older on average than men, and two-thirds of the elderly in need are women, so research on the issue of women and senior citizens is urgent. The research participants include seven female senior citizens from the Seoul-based sports center. The data collection was conducted through in-depth interviews once for 90 to 180 minutes and twice per participant from March to May 2020, and was analyzed using the phenomenological research method of Colaizzi. The analysis results showed that regular life, relationship and interest life, changing life, and satisfying life were factors that acquired and developed positive psychological capital for elderly women, which were possible only if they maintained their health, regularity and relationship. The experience of participants who achieved successful aging by acquiring positive psychological capital through exercise is suggested as a solution to aging social problems, and furthermore, it is expected to serve as a healthy guide for successful aging for young and old people ahead of their old age.

• Korean Journal of Food Science and Technology
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• v.20 no.3
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• pp.331-337
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• 1988

The thermal properties of typical five Indica and five Japonica rice varieties were investigated by Differential Scanning Calorimetry (DSC). There was no significant difference in gelatinization temperature between Indica and Japonica varieties, but the average enthalpy of gelatinization was larger in Indica types than that in Japonica. However, the enthalpy of melting of amylose-lipid complex was larger in Japonica types than that in Indica types. The DSC thermogram of hydrolyzed rice residue included a smaller peak of gelatinization with narrow range of temperature. Retrogradation of gelatinized rice kernel was also determined with DSC theremograms. The endothermic peak areas clearly increased with increasing storage time at $4^{\circ}C$ so that the area could be used as a measure of the relative degree of retrogradation. The results indicated that Samgang variety(Indica) retrograded more rapidly than Chuncheong variety(Japonica).

• Elastomers and Composites
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• v.47 no.3
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• pp.210-215
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• 2012

Whitening phenomena of the EPDM composites with different inorganic filler compositions which were aged at $90^{\circ}C$ for 7 days in air and tap water atmospheres, respectively, were investigated. The aged samples in tap water containing stearic acid exhibited severe whitening phenomena, while all the samples aged in air did not show any whitening. Depending on the filler compositions, there was no big difference in the whitening phenomena. The whitening materials were analyzed using gas chromatography/mass spectrometry (GC/MS), image analysis, energy-dispersive X-ray spectroscopy (EDX), and attenuated total reflectance-Fourier transform infrared spectroscopy (ATR-FTIR). The whitening materials were identified to be salts of stearic acid. The salts of stearic acid were formed by reaction of metal cation in tap water and stearic acid in the sample.

• Journal of Life Science
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• v.27 no.12
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• pp.1515-1522
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• 2017

Most people have a desire to live longer. According to ancient Chinese and Korean mythology, Dongfang Shuo (Dongbang Sahk) lived for 18,000 years. According to a WHO report, the average longevity of humans has extended from 50-odd years in the 1960s to 75-85 years in 2016. Parabiosis, the joining to circulatory systems of two animals, was described as early as the 1860s. It provides a powerful experimental model to investigate the effects of one animal on its partner animal in vivo. Research on reverse aging is an immensely popular in parabiosis studies. In this review, the origin of the parabiosis model and important historical findings based on parabiosis models are presented. Surprising and debated discoveries in aging research are also introduced. Using heterochronic parabiosis of connecting circulatory systems of a young mouse and old mouse, various groups claim to have identified a reverse aging factor, growth differentiation factor 11 (GDF11), which was significantly reduced in blood of old mice. Although the potential existence of any one factor or factors that could reverse aging remains to be confirmed, studies have shown that the parabiosis model is powerful enough to detect reverse aging factors.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2009.06a
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• pp.469-470
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• 2009

본 논문은 전류의 변화에 따른 태양전지 모듈의 열 분포에 대하여 실험하였다. 태양전지 모듈의 경우 내구성의 문제가 대두되고 있는데 그 중에 열에 의한 노화현상이 가장 큰 문제이다. 실제적으로 태양전지 모듈에서 저 전류와 고 전류의 경우에서 서로 상이한 열 분포가 이루어지고 있다. 이번 연구를 통해 열 해석에 있어서 전류에 따른 태양전지 모듈에서의 열에 의한 노화현상을 좀 더 정확히 예측 할 수 있을 것이다.

• Biomedical Science Letters
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• v.2 no.1
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• pp.91-108
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• 1996

The present study was designed to examine effect of short term treadmill and weight-training on aging arophy in the rat skeletal muscle. Male rats of 24 months old were used. Each groups included control, treadmill and weight-training for 4 weeks by using treadmill apparatus and body press apparatus. The histo and cytochemical, ultrastructural and stereological changes in senile skeletal muscles of the rat were observed in the present study. During the training period the body weight and muscular weight in all groups remained constant. The volume density of muscle fiber type IIC and IIB were increased, that of type IIA was decreased, but type I remained constant in treadmill-training group. In weight-training rat, the density of type IIA and IIB were increased, both those of type IIC was decreased. But, all changes of muscle fiber type is not significant. Senile control group some usual formation of mild contraction band, liposuscin pigment and muscular splitting were observed. After treadmill-training, histological and ultrastructural changes occurred in the muscle fiber, such as irregularity of the sarcolemma, interfibrillar vacuolization, longitudinal splitting, and widened I-bond. After weight-training, the changes occurred in the trained muscle fiber, such as appearances of many lysosomes and autophagic vacuoles, severe contraction band, and breakup of myofibrils. Histo and cytochemical studies showed that the activities of succinic dehydrogenase and acid phosphatase remained constant, activities of $Mg^{++}$-ATPase decrease with training. Stereological changes were not observed in the volume and numerical density of all subject component, but the surface density of mitochondrial inner membrane was increased with treadmill-training. These experimental results suggested that endurance training during short-term may result in the adaptible response in senile skeletal muscles. On the other side, weight-training is bad for senile skeletal muscle.

• Proceedings of the KSME Conference
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• 2008.11a
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• pp.1674-1678
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• 2008

본 연구에서는 심장의 세포 변화에서부터 혈류 순환의 시스템 변화까지 일련의 과정을 시뮬레이션 할 수 있는 통합모델을 개발하였다. 본 통합 모델을 이용하여 대동맥의 탄성도 변화 따른 Pulse Wave Velocity를 추정하였으며 심근의 수축 Mechanics의 변화를 시뮬레이션 하였다. 심장은 단순한 구 형상으로 모델링 되었다. 특히 동맥순환의 특성인 Wave propagation 과 Wave deflection의 현상을 모델링하기 위해 기존 모델에서 사용된 동맥계 순환 모델을 수정하였다. 즉 기존의 동맥 모델을 1차원의 운동방정식과 연속방정식을 기반으로 하는 Distributed arterial model로 대체하였다. Distributed arterial model은 혈액의 점성에 의한 에너지 손실, 혈관의 점탄성 효과 그리고 분지 되는 혈관에서의 에너지 손실을 포함하는 정교한 동맥 순환 모델이다. 정교한 동맥계 순환 모델의 동맥 탄성도 값을 조절함으로써 탄성도 변화에 대한 PWV를 계산 할 수 있었다. 이러한 수치적 방법을 사용하여 노화에 따른 동맥벽 탄성도의 저하가 심근세포의 Cross-bridge 동역학에 미치는 영향을 시뮬레이션 하였다.