• Journal of the Korean Chemical Society
• /
• v.34 no.2
• /
• pp.203-210
• /
• 1990

As a possible biocompatible and biodegrable polymer skeleton for drug delivery system, block copolymers of L-lactic acid and L-glutamic acid with different composition were synthesized and characterized. Poly (L-lactide) was prepared by polymerization of L-lactide with zine oxide at $130^{\circ}C$ for 72 hrs. 3-Amino-l-propanol was introduced to poly (L-lactide) by an ester linkage in order to initiate polymerization. Polymerization of $\gamma-benzyl-L-glutamate-N-carboxyanhydride(\gamma-BLG-NCA)$ utiliizing the amino group of modified poly (L-lactide) as an initiator gave rise to the block copoly $(L-lactide-\gamma-benzyl-L-glutamate).$ The NMR study of resulting block copolymers showed that the composition of L-lactic acid and $\gamma-benzyl-L-glutamate$ in block copolymers was depended on the weight ratio of poly (L-lactide) and $\gamma-BLG-NCA.$ The thermal properties of the resulting block copolymers were determined by the differential scanning calorimetry and by the thermogravimetry.

• Bulletin of the Korean Chemical Society
• /
• v.35 no.6
• /
• pp.1806-1808
• /
• 2014

We report the successful preparation of gold nanoparticles (Au NPs) using a novel electroreduction process, which is simple, fast, and environmentally friendly (toxic chemicals such as strong reducing agents are not required). Our process allows for the mass production of Au NPs and adequate particle size control. The Au NPs prepared show high biocompatibility and are non-toxic to healthy human cells. By applying radio-frequency (RF) ablation, we monitored the electro-hyperthermia effect of the Au NPs at different RFs. The Au NPs exhibit a fast increase in temperature to $55^{\circ}C$ within 5 min during the application of an RF of 13 MHz. This temperature rise is sufficient to promote apoptosis through thermal stress. Our work suggests that the selective Au NP-mediated electro-hyperthermia therapy for tumor cells under an RF of 13 MHz has great potential as a clinical treatment for specific tumor ablation.

• Proceedings of the Korea Concrete Institute Conference
• /
• 2008.11a
• /
• pp.517-520
• /
• 2008

Gravity dam use self weight to stand external force like hydraulic pressure. In general, gravity dam concrete is divided into internal and external concrete. Seongdeok dam is gravity dam which is being constructed in Cheongsong-gun, Gyeonsangbuk-do. And upstream cofferdam was constructed to examine the temperature crack due to hydration heat and to decide the height of placement. In this study, we examined the mix design of internal/external concrete and physical properties(compressive strength, adiabatic temperature rise). And we also performed laboratory tests to verify exothermic properties. Lastly, we measured the hydration heat and thermal stress of upstream cofferdam.

• Transactions of the Korean Society of Mechanical Engineers
• /
• v.14 no.2
• /
• pp.453-462
• /
• 1990

The interaction of forced convection-conduction with thermal radiation in laminar boundary layer over a plate fin is studied numerically. The analysis is based on complete solution whereby the heat conduction equation for the fin is solved simultaneously with the conservation equations for mass, momentum and energy in the fluid boundary layer adjacent to the fin. The fluid is a gray medium and diffusion(Rosseland) approximation is used to describe the radiative heat flux in the energy equation. The resulting boundary value problem are convection-conduction parameter N$_{c}$ and radiation-conduction parameter m, Prandtl number Pr. Numerical results are presented for gases with the Prandtl numbers of 0.7 & 5 with values of N$_{c}$ and M ranging from 0 to 10 respectively. The object of this study is to provide the first results on forced convection-radiation interaction in boundary layer flow over a semi-infinite flay plate which can be used for comparisons with future studies that will consider a more accurate expression for the radiative heat flux. The agreement of the results from the complete solution presented by E. M. Sparrow and those from this paper for the special case of M=0 is good. The overall rate of heat transfer from the fin considering radiative effect is higher than that from the fin neglecting radiative effect. The local heat transfer coefficient with radiative effect is higher than that without radiative effect. In the direction from tip to base, those coefficients decrease at first, attain minimum, and then increase. The larger values of N$_{c}$ M, Pr give rise to larger fin temperature variations and the fin temperature without radiative effect is always higher than that with radiative effect.

• Korean Journal of Fisheries and Aquatic Sciences
• /
• v.46 no.5
• /
• pp.582-588
• /
• 2013

The impact of global warming on aquatic systems has been a priority research area in the past decade. However, the possibility that increased temperatures will cause shifts in viral disease outbreaks has not been well addressed. In the present study, with increasing water temperature (WT) in the coastal area of Korea, we estimated the possibility of changes in fish viral diseases. From the present time, WT may rise between 0.62 and $1.7^{\circ}C$ by 2050, and the effect on aquaculture could be more adverse than benefitial. Red seabream iridovirus disease (RSIVD) and viral nervous necrosis (VNN) cause high mortality above 22 and $24^{\circ}C$, respectively, and outbreaks could commence earlier and persist for prolonged periods. Nevertheless, the period of occurrence of viral hemorrhagic septicemia (VHS), which outbreaks at a lower WT (< $18^{\circ}C$), could be shorter than the current infectious period. Thermal stress in fish causes reductions in growth and immunocompetence; thus, increases in summer WT can lead to the development of new viral diseases. WT has a strong influence on fish population dynamics; therefore, entry of new viruses and changes in the prevalence of infection can be expected if carrier fishes are introduced or migrate to Korean waters.

• Atmosphere
• /
• v.26 no.3
• /
• pp.445-459
• /
• 2016

Air temperature deviation (ATD) is one of major indicators to represent spatial distribution of urban heat island (UHI), which is induced from the urbanization. The purpose of this study is to evaluate the accuracy of air temperature deviation about Climate Analysis Seoul (CAS) workbench, which had developed by National Institute Meteorological Science and TU Berlin. Comparison and correlation analysis for CAS ATD including meso-scale air temperature deviation, local-scale air temperature deviation, total air temperature deviation, surface heat flux deviation, cold air production deviation among meso-scale numerical modelling variable in 'Seoul Region', micro-scale numerical modelling in 'Detail Region', and CAS workbench variable using observation data in ground stations. Comparison between night time OBS ATD and CAS ATD show that have most close values. Most of observations ($dT_{max}$ and $dT_{min}$) have highly positive ($dT_{SHP}$, $dT_{CA}$, MD, TD, $f_{BS}$, $f_{US}$, $f_{WS}$, $h_B$) and negative ($f_{VS}$, $f_{TV}$, $h_V$, Z) correlations. However, CAS workbench needs further improvement of both observational framework and analytical framework to resolve the problems; (1) night time OBS ATD of has closer values in compare with at high rise mountain area and (2) correlations are very dependable to meteorological scale.

• Transactions of the Korean Society of Mechanical Engineers A
• /
• v.24 no.11
• /
• pp.2866-2874
• /
• 2000

This paper is concerned with the optimum design for external reinforcement of a nuclear reactor pressure vessel(RPV) in a severe accident. During the severe reactor accident of molten core, the temperature and the pressure in the nuclear reactor rise to a certain level depending on the initial and subsequent condition of a severs accident. The reis of the temperature and the internal pressure cause deterioration of the load carrying capacity and could cause failure of the RPV lower head. The deterioration of failure can be mitigated by the external cooling or the reinforcement of the lower head with additional structures. While the external cooling forces the temperature of an RPV to drop to the desired level, the reinforcement of the lower head can attain both the increase of the load carrying capacity and the temperature drop. The reinforcement of the lower head can be optimized to have the maximum effect on the collapse pressure and the temperature at the inner wall. Optimization results are compared to both the result without the reinforcement and the result with the designated reinforcement.

• Journal of the Korean Chemical Society
• /
• v.36 no.5
• /
• pp.644-651
• /
• 1992

The kinetics of the gas phase reaction of ozone(∼0.5 torr) with sulfur trioxide was investigated in the range of 6∼12 torr pressure at 69∼150${\circ}C$. The reaction rate of ozone with sulfur trioxide was faster than the reaction rate of $O_3 in the presence of CO_2 alone. No evidence for a molecular reaction of O_3 with SO_3 was found and the faster rate is probably due to impurity (HX) from the SO_3 reactant which gives rise to a chain reaction initiated by O_3 ＋ HX → OH ＋ O_2 ＋ X and also SO_3 has a larger collision diameter, which may be attributed to the O3 thermal decomposition more feasibly. The proposed experimental law [-d(O_3)/dt] = k_a(SO_3)(O_3) ＋ k_b(O_3)^{3/2} gives a rate constant ka(M-1 s-1) = (1.55 {\pm} 0.67) {\times} 105 e-{(9.27 0{\pm}0.43)kcal/RT}.$

• Korean journal of applied entomology
• /
• v.19 no.2 s.43
• /
• pp.67-72
• /
• 1980

A mosaic virus disease of ginger plant was investigated to determine its virus group on the basis of host range, physical and chemical properties, serological behavior and electron-microscopic morphology. The disease gave rise to yellowsih and dark-green mosaic on the leaves in the early stage and stunted all the leaves as well as rhizomes in the late stage. In the field about 43\% of the plants were observed to be diseased The disease was able to be artificially infected to the ginger plants by the sap and transmission as well as to 23 other species of plants which were known to be the CMV susceptible plants by the sap transmission; Chenopodium amaranticolar, Nicotiana tabaccum var. Havana, cow pea, cucumber, tomato,... etc. The dilution end point of the virus ranged $10^{-4}-10^{-5}$ and the thermal inactivation point $65-70^{\circ}C$. Serological test showed a positive reaction by a CMV antiserum. An electron microscopy of the purified virus showed that the virus particles were spherical with a diameter of $28-32m\mu$. Virus particles from the infected tissue were observed to be free or aggregated in the mesophyll tissue of artificially infected tobacco plant. The mosaic disease of ginger plants were conclusively suggested to the CMV group.

• Journal of the Korean Society for Precision Engineering
• /
• v.30 no.12
• /
• pp.1303-1312
• /
• 2013

We report an ultra-precision lathe designed to machine micron-scale features on a large-area roll mold. The lathe can machine rolls up to 600 mm in diameter and 2,500 mm in length. All axes use hydrostatic oil bearings to exploit the high-precision, stiffness, and damping characteristics. The headstock spindle and rotary tooling table are driven by frameless direct drive motors, while coreless linear motors are used for the two linear axes. Finite element method modeling reveals that the effects of structural deformation on the machining accuracy are less than $1{\mu}m$. The results of thermal testing show that the maximum temperature rise at the spindle outer surface is approximately $0.5^{\circ}C$. Finally, performance evaluations of the error motion, micro-positioning capability, and fine-pitch machining demonstrate that the lathe is capable of producing optical-quality surfaces with micron-scale patterns with feature sizes as small as $20{\mu}m$ on a large-area roll mold.