• YAKHAK HOEJI
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• v.40 no.1
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• pp.102-111
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• 1996

LB10522 is a new parenteral broad spectrum cephalosporin with a catechol moiety at C-7 position of beta-lactam ring. This compound can utilize tonB-dependent iron transp ort system in addition to porin proteins to enter bacterial periplasmic space and access to penicillin-binding proteins (PBPs) which are the lethal targets of ${\beta}$-lactam antibiotics. The chelating activity of LB10522 to metal iron was measured by spectrophotometrically scanning the absorbance from 200 to 900nm. When $FeCl_3$ was added, optical density was increased between 450 and 800nm. LB10522 was more active against gram-negative strains in iron-depleted media than in iron-replete media. This is due to the increased expression of iron transport channels in iron-depleted condition. LB10522 showed a similar activity against E. coli DC2 (permeability mutant) and E. coli DCO (wild type strain) in both iron-depleted and iron-replete media, indicating a minimal permeaility barrier for LB10522 uptake. LB10522 had high affinities to PBP 3 and PBP 1A, 1B of E. coli. By blocking these proteins, LB10522 caused inhibition of cell division and the eventual death of cells. This result was correlated well with the morphological changes in E. coli exposed to LB10522. Although the in vitro MIC of LB10522 against P. aeruginosa 1912E mutant (tonB) was 8-times higher than that of the P. aeruginosa 1912E parent strain, LB10522 showed a similar in vivo protection efficacy against both strains in the mouse systemic infection model. This result suggested that tonB mutant, which requires a high level of iron for normal growth, might have a difficulty in surviving in their host with an iron-limited environment.

• Corrosion Science and Technology
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• v.11 no.6
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• pp.280-285
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• 2012

Aluminum is on active metal, but it is well known that its oxide film plays a role as protective barrier which is comparatively stable in air and neutral aqueous solution. Thus, aluminum alloys have been widely applied in architectural trim, cold & hot-water storage vessels and piping etc., furthermore, the aluminum alloy of AC8A have been widely used in mold casting material of engine piston because of its properties of temperature and wear resistance. In recent years, the oil price is getting higher and higher, thus the using of low quality oil has been significantly increased in engines of ship and vehicle. Therefore it is considered that evaluation of corrosion resistance as well as wear resistance of AC8A material is also important to improve its property and prolong its lifetime. In this study, the effect of solution and tempering heat treatment to corrosion and wear resistance is investigated with electrochemical method and measurement of hardness. The hardness decreased with solution heat treatment compared to mold casting condition, but its value increased with tempering heat treatment and exhibited the highest value of hardness with tempering heat treatment temperature at $190^{\circ}C$ for 24hrs. Furthermore, corrosion resistance increased with decreasing of the hardness, and decreased with increasing of the hardness reversely. As a result, it is suggested that the optimum heat treatment to improve both corrosion and wear resistance is tempering heat treatment temperature at $190^{\circ}C$ for 16hrs.

• Journal of Korean Society on Water Environment
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• v.30 no.4
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• pp.394-402
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• 2014

High-voltage dielectric discharges are an emerging technique in environmental pollutant degradation, which are characterized by the production of hydroxyl radicals as the primary degradation species. The initiation and propagation of the electrical discharges depends on several physical, chemical, and electrical parameters such as 1st and 2nd voltage of power, gas supply, conductivity and pH. These parameters also influence the physical and chemical characteristics of the discharges, including the production of reactive species such as OH, $H_2O_2$ and $O_3$. The experimental results showed that the optimum 1st voltage and oxygen flow rate for RNO (N-Dimethyl-4-nitrosoaniline, indicator of the generation of OH radical) degradation were 160 V (2nd voltage of is 15 kV) and 4 L/min, respectively. As the 2nd voltage (4 kV to 15 kV) was increase, RNO degradation was increased and, generated $H_2O_2$ and $O_3$ concentration were increased. The conductivity of the solution was not influencing the RNO degradation, $H_2O_2$ and $O_3$ generation. The pH effect on RNO degradation was not high. However, the lower pH and the conductivity, the higher $H_2O_2$ and $O_3$ generation were observed.

• Journal of the Society of Naval Architects of Korea
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• v.53 no.3
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• pp.228-236
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• 2016

Extraordinarily the establishment of towing tank has been initiated after the allocation of space at the basement floor of existing building through remodeling procedure. Therefore the asymmetric tank should be unavoidably determined by compromising with the allowable space and existing building structure. Consequently the shape of towing carriage ought to be selected as a cantilever type to match with the given environmental conditions. Finally the major role of the towing tank has been configured on the fundamental research work for the high speed marine vehicles. Due to the limited length of towing tank, it is appeared that the carriage should accelerated with 1.2m/sec² which is equivalent to twice of the maximum acceleration in ordinary practices on design application of carriage. In such a condition the exerted total power of motor could not be converted to traction force of the carriage without slip for the acceleration. To overcome these difficulties the contact pressure of a horizontal traction wheel to rail has been reinforced by the elastic recovery force of springs on supporting rollers. It is believed that the design experience of the high speed towing carriage under unusual circumferential condition and acceleration barrier could be utilized not only on the design of high speed towing carriage but also on the improvement of existing facilities.

• Proceedings of the KIEE Conference
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• 1994.07b
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• pp.1320-1322
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• 1994

Photoisomerization characteristics of 4-octyl-4'-(5-carboxy-pentamethyleneoxy) azobenzene molecules (8A5H) were attained by measurement of absorbtion spectra. 8A5H in chroloform($6.0{\times}10^{-5}[M/l]$) shows trans to cis and cis to trans isomerization by irradiation of lights of 360[nm] and 450[nm] wavelength. From LB monolayer films of 8A5H, also the cis/trans photoisomerization was obtained and it has reversibility and memory characteristics. We are now trying to detect these properties of 8A5H electrically. On this paper, we investigated the structural changes of monolayer on the water surface by measuring the displacement current as a preliminary experiment. The measuring system was constructed at home-made Kuhn type LB(Langmuir-Blodgett) deposition apparatus. 8A5H solution was spreaded at the air-water interface and the currents induced by the dynamic behavior of molecules were measured when the molecules were pressed by barrier. The reversibility of displacement currents by compression and expansion was obtained from 8A5H molecules, which shows the compressed molecules have a tendency to disperse after the compression. From this experiment, we conclude that the behavior of molecules on water surface can be monitored electrically by using this current measuring method, and this method can also be applied to detect the photoisomerization of monolayers on water surface.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2010.03a
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• pp.21-21
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• 2010

(Ba,Sr)$TiO_3$ (BST) thin film with a perovskite structure has potential for the practical application in various functional devices such as nonvolatile-memory components, capacitor, gate insulator of thin-film transistors, and electro-optic devices for display. Normally, the BST thin films derived from sol-gel and sputtering are amorphous or partially crystalline when processed below $600^{\circ}C$. For the purpose of integrating BST thin film directly into a Si-based read-out integrated circuit (ROIC), it is necessary to process the BST film below $400^{\circ}C$. The microstructural and electrical properties of low-temperature crystallized BST film were studied. The BST thin films have been fabricated at $350^{\circ}C$ by UV-assisted rapidly thermal annealing (RTA). The BST films are in a single perovskite phase and have well-defined electrical properties such as high dielectric constant, low dielectric loss, low leakage current density, and high breakdown voltage. Photoexcitation of the organics contained in the sol-gel-derived films by high-intensity UV irradiation facilitates elimination of the organics and formation of the single-crystalline phase films at low temperatures. The amorphous BST thin film was transformed to a highly (h00)-oriented perovskite structure by high oxygen pressure processing (HOPP) at as low as $350^{\circ}C$. The dielectric properties of BST film were comparable to (or even better than) those of the conventionally processed BST films prepared by sputtering or post-annealing at temperature above $600^{\circ}C$. When external pressure was applied to the well-known contractive BST system during annealing, the nucleation energy barrier was reduced; correspondingly, the crystallization temperature decreased. The UV-assisted RTA and HOPP, as compatible with existing MOS technology, let the BST films be integrated into radio-frequency circuit and mixed-signal integrated circuit below the critical temperature of $400^{\circ}C$.

• Journal of the Korean Applied Science and Technology
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• v.28 no.2
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• pp.170-177
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• 2011

Transdermal drug delivery(TDS) offers many important advantages. For instance, it is easy and painless, it protects the active compound from gastric enzymes, and it avoids the hepatic first-pass effect. Also, it is simple to terminate the therapy if any adverse or undesired effect occurs. But skin is a natural barrier, and only a few drugs can penetrate the skin easily and in sufficient quantities to be effective. Therefore, in recent years, numerous studies have been conducted in the area of penetration enhancement. The most commonly used transdermal system is the skin patch using various types of technologies. Compared with other method of dosage, it is possible to use for a long term. It is also possible to stop the drug dosage are stopped if the drug dosage lead to side effect. Polysaccharide, such as xanthan gum and algin were selected as base materials of TDS. Also, these polymers were characterized in terms of enhancers and drug contents. Among these polysaccharide, the permeation rate of Paroxetine such as lipophilic drug was the fastest in xanthan gum matrix in vitro. We used glycerin, PEG400 and PEG800 as enhancers. Since dermis has more water content(hydration) than the stratum corneum, skin permeation rate at steady state was highly influenced when PEG400 was more effective for lipophilic 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.

• Journal of the Microelectronics and Packaging Society
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• v.12 no.2 s.35
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• pp.129-134
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• 2005

Electroplating copper is the important role in formation of 3D stacking interconnection in SiP (System in Package). The I-V characteristics curves are investigated at different electrolyte conditions. Inhibitor and accelerator are used simultaneously to investigate the effects of additives. Three different sizes of via are tested. All via were prepared with RIE (reactive ion etching) method. Via's diameter are 50, 75, $100{\mu}m$ and the height is $100{\mu}m$. Inside via, Ta was deposited for diffusion barrier and Cu was deposited fer seed layer using magnetron sputtering method. DC, pulse and pulse revere current are used in this study. With DC, via cannot be filled without defects. Pulse plating can improve the filling patterns however it cannot completely filled copper without defects. Via was filled completely without defects using pulse-reverse electroplating method.

• Journal of the East Asian Society of Dietary Life
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• v.22 no.6
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• pp.734-743
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• 2012

High sodium consumption is a significant nutrition problem in South Korea; however, few studies have examined the awareness and practice of dietitians with respect to low sodium diet in schools. In this study, we collected data from 211 dietitians in 2012. Most respondents indicated that sodium reduction was important in school meals (very important 40.5%, somewhat important 55.6%); however, they rarely checked the sodium content in the nutrition labels of processed foods (never/rarely 74.2%, sometimes 18.7%, always/often 7.2%). The main reason for not checking the sodium content was 'no nutrition table on some processed foods' (38.5%). The most important barrier to sodium reduction in school meals was overcoming the negative taste of students related to a reduced-sodium diet (70.4%). The most frequently used processed foods were processed meat (e.g. ham, bacon) (48.3%), frozen dumplings and noodles (33.8%), and sausage and dressing (14.5%) in school meals. The proportion of dietitians who used processed food ${\geq}$ 2 times per week for the school menu was 72.2% in high school, 28.4% in middle school and 12.4% in elementary school (p<0.05). Upon ranking of the importance of nutrients in school menus, calories received the highest score (4.35 points), followed by macronutrient ratios (4.30), calcium (4.06), iron (3.44) and sodium (3.20). Although most dietitians recognized that sodium reduction was important in school menu planning, they had poor dietary practices. It is suggested that we educate dietitians as well as students about the importance and practice of a reduced sodium diet. Furthermore, it is critical to develop diverse low sodium recipes and have a required nutrition labeling system for all processed foods. Overall, the results of this study could serve as a guide to planning effective nutrition programs to reduce sodium consumption in school feeding programs.

• Journal of the Korean Chemical Society
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• v.28 no.3
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• pp.163-169
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• 1984

The transport rates of $K^+$ion through CHCl$_3$ liquid membrane containing dibenzo-18-crown-6(DBC) as a carrier molecule have been determined at $25^{\circ}C$. The transport rates depend highly on the ion concentration and on the nature of anion. It is concluded that $K^+$ions are transported in the form of ion-pair. In the case of potassium picrate, however, it is found that the transport proceeds with the formation of the incomplete ion-pair in the concentration less than 1.0 ${\times}10^{-3}$M of picrate, while with the complete formation of ion-pair in the concentration more than 1.0 ${\times}10^{-3}$M of picrate. Seven steps of the transport process are suggested and they can be illustrated in terms of energy barrier model as a function of the position of ionic species in the membrane.