• Carbon letters
• /
• v.14 no.2
• /
• pp.121-125
• /
• 2013

In this study, PtRu nanoparticles deposited on binary carbon supports were developed for use in direct methanol fuel cells using carbon blacks (CBs) and multi-walled carbon nanotubes (MWCNTs). The particle sizes and morphological structures of the catalysts were analyzed using X-ray diffraction and transmission electron microscopy, and the PtRu loading content was determined using an inductively coupled plasma-mass spectrometer. The electrocatalytic characteristics for methanol oxidation were evaluated by means of cyclic voltammetry with 1 M $CH_3OH$ in a 0.5 M $H_2SO_4$ solution as the electrolyte. The PtRu particle sizes and the loading level were found to be dependent on the mixing ratio of the two carbon materials. The electroactivity of the catalysts increased with an increasing MWCNT content, reaching a maximum at 30% MWCNTs, and subsequently decreased. This was attributed to the introduction of MWCNTs as a secondary support, which provided a highly accessible surface area and caused morphological changes in the carbon supports. Consequently, the PtRu nanoparticles deposited on the binary support exhibited better performance than those deposited on the single support, and the best performance was obtained when the mass ratio of CBs to MWCNTs was 70:30.

• Journal of Hydrogen and New Energy
• /
• v.31 no.4
• /
• pp.345-350
• /
• 2020

Hydrogen is an green energy without pollution. Recently, fuel cell electric vehicle has been commercialized, and many studies have been conducted on hydrogen tanks for vehicles. The hydrogen tank for vehicles can be charged up to 70 MPa pressure. In this study, the change in filling time, pressure, and temperature for each hydrogen level in a 59 L hydrogen tank was predicted by numerical analysis. The injected hydrogen has the properties of real gas, the temperature is -40℃, and the mass flow rate is injected into the tank at 35 g/s. The initial tank internal temperature is 25℃. Realizable k-epsilon turbulence model was used for numerical analysis. As a result of numerical analysis, it was predicted that the temperature, charging time, and the mass of injected hydrogen increased as the residual capacity of hydrogen is smaller.

• Biomedical Science Letters
• /
• v.11 no.1
• /
• pp.1-8
• /
• 2005

Fibrates are a class of hypolipidemic agents whose effects are mediated by activation of a specific transcription factor called the peroxisome proliferator-activated receptor $\alpha\;(PPAR\alpha).\;PPAR\alpha$ regulates the pathways of lipid catabolism such as fatty acid oxidation and the triglyceride metabolism, resulting in the treatment of hyperlipidemia. The decreased levels of plasma triglycerides by fibrates are responsible for hypertrophy and hyperpalsia of adipose cells. To determine whether fenofibrate regulates adipogenesis in female C57BL/6J mice, we measured the effects of fenofibrate on not only body weight, adipose tissue mass and serum triglycerides, but also the histology of adipose tissue and the expression of adipocyte marker genes. Fenofibrate did not inhibit high fat diet-induced increases in body weight, adipose tissue mass and serum triglycerides. Furthermore, fenofibrate did not cause the changes in the size and number of adipocytes and the expression of adipocyte-specific genes such as leptin and $TNF\alpha$. Therefore, this study demonstrates that fenofibrate does not affect adipogenesis in female mice.

• Journal of Korean Neurosurgical Society
• /
• v.49 no.4
• /
• pp.237-240
• /
• 2011

Ganglion cysts usually arise from the tendon sheaths and tissues around the joints. It is usually associated with degenerative arthritic changes in older people. Ganglion cyst in the spine is rare and there is no previous report on case that located in the intervertebral foramen and compressed dorsal root ganglion associated severe radiculopathy. A 29-year-old woman presented with severe left thigh pain and dysesthesia for a month. Magnetic resonance imaging revealed a dumbbell like mass in the intervertebral foramen between second and third lumbar vertebrae on the left side. The lesion was removed after exposure of the L2-L3 intervertebral foramen. The histological examination showed fragmented cystic wall-like structure composed of fibromyxoid tissue but there was no lining epithelium. A ganglion cyst may compromise lumbar dorsal root ganglion when it located in the intervertebral foramen. Although it is very rare location, ganglion cyst should be included in the differential diagnosis for intervertebral foraminal mass lesions.

• Analytical Science and Technology
• /
• v.30 no.2
• /
• pp.68-74
• /
• 2017

The volatile components in 'Fuji' apple were effectively determined by a headspace solid-phase microextraction (HS-SPME) combined with gas chromatography-mass spectrometry (GC-MS). A total of 48 volatile components were identified and tentatively characterized based on National Institute of Standards and Technology (NIST) MS spectra library and the Kovats GC retention index I (RI). The harvested Fuji apples were divided into two groups: 1-methylcyclopropene (1-MCP) treated and non-treated (control) samples for finding important indicators between two groups. The major volatile components of both apples were 2-methylbutyl acetate, hexyl acetate, butyl 2-methylbutanoate, hexyl butanoate, hexyl 2-methylbutanoate, hexyl hexanoate and farnesene. No significant differences of these major compounds between 1-MCP treated and non-treated apples were observed during 1 month storage. Interestingly, the amount of off-flavors, including 1-butanol and butyl butanoate, in 1-MCP treated apples decreased over 5 months, and then increased after 7 months. However, non-treated apples did not show significant changes for off-flavors during 7 month storage (p<0.05). The non-treated apples also contained the higher levels of two off-flavors than 1-MCP treated apples. These two compounds, 1-butanol and butyl butanoate, can be used as quality indicators for the quality evaluation of Fuji apple.

• The Journal of Pediatrics of Korean Medicine
• /
• v.24 no.2
• /
• pp.49-58
• /
• 2010

Objectives This study was performed to investigate the effects of obesity, food, physical activity and stress on blood pressure changes for children and for adolescents. Methods The participants were the first and the fourth grade elementary school students and the first grade of middle school students. They were asked to measure the blood pressure, height, weight and were asked to complete questionnaires. Results The systolic and diastolic blood pressure of male was significantly higher than that of female and the prevalence of hypertension among the first and the fourth grade elementary school students and the first grade of middle school students were 15.6%, 13.6%, and 7.8%, respectively. Height, weight and body mass index (BMI) were highly correlated with the level of blood pressure. However, food, and physical activity, stress and depression were poorly correlated with the level of blood pressure. Conclusions This study proved that blood pressures in children and in adolescent were closely related with obesity, sex, and height.

• Clinical and Experimental Pediatrics
• /
• v.54 no.11
• /
• pp.436-442
• /
• 2011

An anthropometric survey is one of the most important approaches to use when evaluating the health status of children. Secular trends in body sizes, such as height, weight, head circumference, chest circumference, and body mass index showed significant changes over 40 years in Korea. A series of periodic surveys were conducted in 1967, 1975, 1985, 1997, and 2005 by the Korean Pediatric Society and Ministry of Health and Welfare. The quality of data from school health examinations and the Korea National Health and Nutrition Examination Survey has improved, so we can use them now as resources for anthropometric analysis. The final height differences between 1965 and 1997 were 4.5 cm both in boys (168.9 cm in 1965; 173.4 cm in 1997) and girls (155.9 cm in 1965; 160.4 cm in 1997). The differences between 1997 and 2005 were 0.9 cm in boys (174.3cm in 2005) and 0.8 cm in girls (161.2 cm in 2005). There was no difference in final height measurements between 2005 and 2010. An increase in body size at earlier teen ages was pronounced during these decades compared to the previous generation; however, little change has been identified more recently. Body size has been increasing, and obesity has become more prevalent. Systems that gather data should be updated in order to cope with these secular trends. In an upcoming era of secular trends that would be in a slow transition, several surveys that include body measurements should be prepared to meet future needs.

• Clinical and Experimental Pediatrics
• /
• v.61 no.4
• /
• pp.132-134
• /
• 2018

We report a unique case of intestinal duplication detected on posterior reversible encephalopathy syndrome (PRES) in a 13-year-old girl. She was admitted to the pediatric Emergency Department because of generalized seizures. Radiological assessment revealed a large, well-defined, thick-walled cystic lesion in the mid abdomen, suggestive of duplication cyst associated to a PRES. Exploration confirmed the diagnosis of ileal duplication cyst, and the mass was resected. The postoperative course was uneventful. Both hypertension and neurological dysfunction resolved after the mass resection. A follow-up brain magnetic resonance imaging was performed 9 months later and showed complete resolution of the cerebellar changes. Although extrinsic compression of the retroperitoneal structures has not been reported in the literature as a complication of duplication cyst, we strongly believe that this is the most logical and plausible hypothesis that would explain the pathogenesis of PRES in our patient.

• Structural Engineering and Mechanics
• /
• v.16 no.1
• /
• pp.17-34
• /
• 2003

This paper presents a damage assessment procedure applied to periodic spring mass systems using an eigenvalue sensitivity-based method. The damage is directly related to the stiffness reduction of the damage element. The natural frequencies of periodic structures with one single disorder are found by adopting the transfer matrix approach, consequently, the first order approximation of the natural frequencies with respect to the disordered stiffness in different elements is used to form the sensitivity matrix. The analysis shows that the sensitivity of natural frequencies to damage in different locations depends only on the mode number and the location of damage. The stiffness changes due to damage can be identified by solving a set of underdetermined equations based on the sensitivity matrix. The issues associated with many possible damage locations in large structural systems are addressed, and a means of improving the computational efficiency of damage detection while maintaining the accuracy for large periodic structures with limited available measured natural frequencies, is also introduced in this paper. The incomplete measurements and the effect of random error in terms of measurement noise in the natural frequencies are considered. Numerical results of a periodic spring-mass system of 20 degrees of freedom illustrate that the proposed method is simple and robust in locating single or multiple damages in a large periodic structure with a high computational efficiency.

• The Research Journal of the Costume Culture
• /
• v.18 no.3
• /
• pp.550-558
• /
• 2010

Russian Constructivism, which took the lead in the Russian trend of art until the late 1920's, was influenced by European Cubism and Futurism. Breaking away from the previous realistic tendency, Russian Constructivism, to meet the ideology of the revolution, insisted the "Art into Street" and the "Art in Industry" with its abstract and geometric design. Russian Constructivism effected paintings of mid 1920's, as well as Industrial design and costume design. This operated remarkable changes in Russian form of costume and textile area. An unusual situation like revolution had provided the social justification to develop a new costume design not for the special class of people, but for the general public. In this atmosphere, the plan of clothing mass production began to progress. Although the Russian Constructivism costume of arts shows the similarity in the trend of fashion and the physical forms of those days, its fundamental idea in manufacturing costumes was 'to create costumes to be possible to mass-produce and to be wearable to anyone regardless of the social class'. Therefore, Constructivism costume of arts pursued dynamism and geometric form through non-objective design that has broken away from the handcrafted and traditional standards of the past. These distinct characteristics served as a momentum to seek costume design based on productivity and functionality.