• Journal of the Korean Applied Science and Technology
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• v.17 no.1
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• pp.43-48
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• 2000

Drug delivery system(DDS) applied to various fields, such as medicine, cosmetics, agriculture and necessities of life. Among these application fields, DDS is often used as the method of drug dosage into the epidermic skin. We investigated characters of transdermal therapeutic system(TTS) and the skin permeability of that with applying DDS. Chitosan was selected as material of TTS. We investigated the permeation of chitosan ointment containing drug in rat skin using horizontal membrane cell model. Permeation properties of materials were investigated for water-soluble drug such as riboflavin in vitro. We used glycerin, PEG 600 and oleic acid as enhancers. Since dermis has more content water(hydration) than the stratum corneum, skin permeation rate at steady state was highly influenced when glycerin was used in water-soluble drug. The permeation rate of content enhancer and drug was found to be faster than that of content water-soluble drug only. These results showed that skin permeation rate of drug across the composite was manly dependent on the property of ointment base and drug. Proper selection of the polymeric materials which resemble and enhance properties of the delivering drug was found to be important in controlling the skin permeation rate.

• International Journal of Naval Architecture and Ocean Engineering
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• v.8 no.5
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• pp.423-433
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• 2016

In this paper, we consider the cybersecurity issue of ship information system (SIS) from a new perspective which is called opacity. For a SIS, its confidential information (named as "secret") may be leaked through the working behaviors of each Distributed Control Unit (DCU) from an outside observer called an "intruder" which is able to determine ship's mission state by detecting the source of each data flow from the corresponding DCUs in SIS. Therefore we proposed a dual layer mechanism to enforce opacity by activating non-essential DCU during secret mission. This mechanism is calculated by two types of insertion functions: Safety-assured insertion function ($f_{IS}$) and Admissibility-assured insertion function ($f_{IA}$). Due to different objectives, $f_{IS}$ is designed to confuse intruder by constructing a non-secret behaviors from a unsafe one, and the division of $f_{IA}$ is to polish the modified output behaviors back to normal. We define the property of "$I_2$-Enforceability" that dual layer insertion functions has the ability to enforce opacity. By a given mission map of SIS and the marked secret missions, we propose an algorithm to select $f_{IS}$ and compute its matchable $f_{IA}$ and then the DCUs which should be activated to release non-essential data flow in each step is calculable.

• Journal of Korea Foundry Society
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• v.10 no.5
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• pp.435-443
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• 1990

By using the centrifugal atomization, which is one of the rapid solidification processes, Al-5,10wt%Pb alloys which are monotectic alloys were melted at 150K over two liquid phase line in the phase diagram. The melted alloy was poured on the rotating disk, being made into atomized powders, and then the solidified microstructure and morphology of the powder were investigated. This study converted the produced powders into strips by strained powder rolling. According to sintering temperature, the microstructure and hardness were investigated. The solidified structure of the powders were almost cellular dendritic structure. Pb particles ($2.0-3.0{\mu}m$) were fairl distributed in the Al matrix. Powder shapes were irregular. Rolling property and the compacting was good, respectively, because of increasing mechanical interlocking and surface area in the small size powders. With increasing temperature, the boundarys of powders were in porous form due to the diffusion. Pb particles which were surrounding the pores were inverse-segregated at the surface of the powders. With increasing of sintering temperature, the hardness of the powders and the strips decreased. In particular rolling-strip, the hardness abruptly decreased due to the release of work-hardening.

• BMB Reports
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• v.47 no.2
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• pp.69-79
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• 2014

$Ca^{2+}$ release from intracellular stores and influx from extracellular reservoir regulate a wide range of physiological functions including muscle contraction and rhythmic heartbeat. One of the most ubiquitous pathways involved in controlled $Ca^{2+}$ influx into cells is store-operated $Ca^{2+}$ entry (SOCE), which is activated by the reduction of $Ca^{2+}$ concentration in the lumen of endoplasmic or sarcoplasmic reticulum (ER/SR). Although SOCE is pronounced in non-excitable cells, accumulating evidences highlight its presence and important roles in skeletal muscle and heart. Recent discovery of STIM proteins as ER/SR $Ca^{2+}$ sensors and Orai proteins as $Ca^{2+}$ channel pore forming unit expedited the mechanistic understanding of this pathway. This review focuses on current advances of SOCE components, regulation and physiologic and pathophysiologic roles in muscles. The specific property and the dysfunction of this pathway in muscle diseases, and new directions for future research in this rapidly growing field are discussed.

• Proceedings of the Materials Research Society of Korea Conference
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• 2010.05a
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• pp.44.1-44.1
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• 2010

poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) is a bacterially derived copolymer produced by fermentation. PHBV has been attractive because of its potential environmental, pharmaceutical and biomedical applications. Recently, the electrospinning technique has been used to fabricate fibrous mat for biomedical applications such as artificial blood vessel, drug release and scaffolds, because this method is simple and easy to get ultrafine polymer fibers. Depending on speed of rotation drum collector, fiber structure was different. In this work, PHBV fiber was aligned by electrospinnning machine. Furthermore, alignment of PHBV fiber mats was given angle such as $45^{\circ}$, $60^{\circ}$ and $90^{\circ}$. The morphology of each aligned PHBV fiber mat was observed by SEM technique. The mechanical property was evaluated depending on alignment angle. Especially, cell attachment ability depending on alignment of PHBV fiber mats was carried out using MG- 63 osteoblast like cells.

• Journal of the Korean Society of Laryngology, Phoniatrics and Logopedics
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• v.4 no.1
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• pp.24-32
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• 1991

Cleft palate or velopharyngeal incompetence shows many disorders and disabilities affecting speech transmission. including distortion. substitution. and the nasalization of the vowels. The nasalized vowels are produced primarily by lowering of the velum. resulting in opening a side passage for the air flow through the nasal cavity. These abnormal movements give rise to complex modification of the physical property of the sound or in the sound spectrum. The authors employed Sonagraph$^{\circledR}$ as a sound analyzer in order to ascertain the features which characterize the nasalization of vowels. Twenty healthy Korean male adult voluteers were analyzed in artificial conditions of anterior and posterior nasal obstruction. and velo-pharyngeal incompetence. The results were as follows : 1) Fundamental frequency was not changed by nasal obstruction or velopharyngeal incompetence. 2) There was no significant difference of the formant intensity between normal and nasal vowels. 3) In VPI, a decrease of the frequency of $F_2$ was observed in /e/ and /i/ vowels(p<0.001). 4) In VPI, the $F_2$ was frequently missed in /o/ and /u/ vowels. 5) In the consonant spectra of VPI, the 'release burst' was usually not observed.

• Archives of Pharmacal Research
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• v.26 no.5
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• pp.426-431
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• 2003

This study was carried out to investigate the addition of water-soluble isoflavone into milk by means of microencapsulation technique. The yield of microencapsulation, sensory attributes, and capsule stability of water-soluble isoflavone microcapsules in milk were measured. Coating materials used was polyglycerol monostearate (PGMS), and core material was water-soluble isoflavone. The encapsulation yield of water-soluble isoflavone with PGMS was 67.2% when the ratio of coating material to core material was 15 : 1. The rate of water-soluble isoflavone release from capsules was 18, 19, and 25% when stored at 4,20, and $30^{\circ}C$ for 12 days in milk, respectively. In sensory evaluation, beany flavor and color of microencapsuled water-soluble isoflavone added milk were significantly different from uncapsuled water-soluble isoflavone added milk, however, bitterness was not significantly different. In vitro study, micro-capsules of water-soluble isoflavone in simulated gastric fluid with the range of 3 to 6 pHs were released 3.0∼15.0%, however, the capsules in simulated intestinal fluid with pH 7 were released 95.7% for 40 min incubation time. In conclusion, this study provided that PGMS as coating materials was suitable for the microencapsulation of water-soluble isoflavone, and the capsule containing milk was almost not affected with sensory attribute.

• Journal of Pharmacopuncture
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• v.23 no.1
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• pp.1-7
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• 2020

Nicotine, primary component of tobaco produces craving and withdrawal effect both in humans and animals. Nicotine shows a close resemblance to other addictive drugs in molecular, neuroanatomical and pharmacological, particularly the drugs which enhances the cognitive functions. Nicotine mainly shows its action through specific nicotinic acetylcholine receptors located in brain. It stimulates presynaptic acetylcholine receptors thereby enhancing Ach release and metabolism. Dopaminergic system is also stimulated by it, thus increasing the concentration of dopamine in nuclear accumbens. This property of nicotine according to various researchers is responsible for reinforcing behavioral change and dependence of nicotine. Various researchers have also depicted that some non dopaminergic systems are also involved for rewarding effect of nicotinic withdrawal. Neurological systems such as GABAergic, serotonergic, noradrenergic, and brain stem cholinergic may also be involved to mediate the actions of nicotine. Further, the neurobiological pathway to nicotine dependence might perhaps be appropriate to the attachment of nicotine to nicotinic acetylcholine receptors, peruse by stimulation of dopaminergic system and activation of general pharmacological changes that might be responsible for nicotine addiction. It is also suggested that MAO A and B both are restrained by nicotine. This enzyme helps in degradation dopamine, which is mainly responsible for nicotinic actions and dependence. Various questions remain uninsurable to nicotine mechanism and require more research. Also, various genetic methods united with modern instrumental analysis might result for more authentic information for nicotine addiction.

• The Transactions of the Korean Institute of Electrical Engineers C
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• v.52 no.8
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• pp.325-329
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• 2003

Effects of thermal treatment on the structural properties of diamond-like carbon (DU) films were examined. The DLC films were deposited by using a modified filtered cathodic vacuum arc (FCVA) deposition system and by varying the negative substrate bias voltage, deposition time, and nitrogen flow rate. Thermal treatment on DLC films was performed using a rapid thermal annealing (RTA) process at $600^{\circ}C$ for 2min. Raman spectroscopy, x-ray photoemission spectroscopy (XPS), atomic force microscope (AFM), and surface profiler were used to characterize the I$_{D}$I$_{G}$ intensity ratio, sp$^3$ hybrid carbon fraction, internal stress, and surface roughness. It was found for all the deposited DLC films that the RTA-treatment results in the release of internal compressive stress, while at the same time it leds to the decrease of sp$^3$ fraction and the increase of I$_{D}$I$_{G}$ intensity ratio. It was also suggested that the thermal treatment effect on the structural property of DLC films strongly depends on the diamond-like nature (i.e., sp$^3$ fraction) of as-deposited film.ed film.

• Journal of the Korean Solar Energy Society
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• v.26 no.1
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• pp.21-28
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• 2006

Changes in building construction methods and repairing of older buildings have reduced infiltration rate. Synthetic materials, release airborne particles and uneven healthy odor are increased. For preventing pollutants introduce fresh outdoor air into the building, simply letting fresh outdoor air into building, however, Is not a cost-effective way to ventilation. When additional ventilation is added to an existing HVAC system, the heating and cooling equipment, often cannot handle the increased load. A HRV provides a way to minimize in energy costs while introducing fresh air to a building. In this study, the economical research of HRV, made of three types of materials, are conducted. Heat recovering characteristics are studied at seasonal outdoor air conditions based on the outdoor air property condition at, Seoul in 2002. As a results, the average sensible effectiveness is 0.75 in the sensible heat exchanger and average total effectiveness is 0.65 in the total heat exchanger. The pay back period of the sensible heat exchangers are $3.2{\sim}3.5$ year and it of total heat exchanger is 2.2 years.