• Journal of the Korean Society of Visualization
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• v.8 no.4
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• pp.54-59
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• 2010

A laser moxibustion therapy device having effect similar to that of traditional moxibustion is being developed using 1064 nm infrared laser. The therapy device allows direct interaction of laser light with the tissue rendering temperature distribution both on the skin surface and deep under the skin. We made a device that could measure temperature of deep under the surface of agar gel tissue phantom using thermocouples. A thermal imaging camera was used to verify results from the temperature measurement device. We compared the characteristics of heat transfer inside the tissue phantom during moxibustion and laser irradiation. The temperature distribution measured by thermocouples was found to be similar to that of distribution given by thermal imaging camera.

• Applied Chemistry for Engineering
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• v.33 no.2
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• pp.210-215
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• 2022

Two types of lignin materials with a different surface ionic character were used and polypyrrole layer was introduced on the lignin surface to obtain polypyrrole@lignin and polypyrrole@lignosulfonate composites using a simple chemical oxidation polymerization, reported in a previous article. Polypyrrole was effectively prepared regardless of the lignin type and the resulting composites were investigated using scanning electron microscope (SEM), cyclic voltammetry (CV), and impedance analysis. SEM and CV results showed that the obtained composites retained stable electrochemical properties after introduction of polypyrrole on the lignin surface. Impedance analyses showed that the surface properties of composites were dependent on lignin characteristics. In addition, the composites were embedded in agarose, an gelifying agent, to obtain conductive gels. It was found that the conductive gels possessed an electrical conductivity and also retained stable electrochemical properties, which indicated that the conductive gels might be useful for some applications.

• Journal of the Korean Society of Visualization
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• v.6 no.2
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• pp.45-50
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• 2008

It has been found that the colony size of bacteria grown on an agar plate decreases with increasing agar gel concentration. Evidenc from recent studies suggests that the bacterial colony dynamics is closely related with the mechanical properties of the substrate. We investigate whether bacterial growth on the agar substrate is controlled mostly by the nutrients' diffusion which is hindered more in porous medium than in solution. The number of bacterial cells in single colonies is found to be inversely correlated with agar concentration. High-resolution live cell imaging at the single bacterium level confirms that the bacterial growth rate is reduced with increasing agar concentration. There is a strong correlation between the slowed diffusion and the reduced number of cells in a high concentration of agar medium.

• Korean Journal of Microbiology
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• v.34 no.3
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• pp.132-136
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• 1998

Molecular analyses of natural microbial communities are often dependent upon the obtainments of pure nucleic acids. The four methods (elution after agarose gel electrophoresis, G-75 microspin columns, hydroxyapatite mi-crospin columns, and polyvinylpolypyrrolidone (PVPP) microspin columns) were compared for the removal of PCR-inhibitory humic substances from the crude DNA extracts of marine sediment samples. The PVPP microspin columns have shown superior removal of humic substances from the crude DNA extract of marine sediment samples, with yield of $4.8{\mu}g/g$ (dry weight of sediment). The purified DNA by this rapid method was pure enough to amplify 1.5 kb fragment corresponding almost full length of 16S rRNA genes.

• Investigative Magnetic Resonance Imaging
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• v.12 no.2
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• pp.131-141
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• 2008

Purpose : To investigate the feasibility and accuracy of Proton Resonance Frequency (PRF) shift based magnetic resonance (MR) temperature mapping utilizing the self-developed center array-sequencing phase unwrapping (PU) method for non-invasive temperature monitoring. Materials and Methods : The computer simulation was done on the PU algorithm for performance evaluation before further application to MR thermometry. The MR experiments were conducted in two approaches namely PU experiment, and temperature mapping experiment based on the PU technique with all the image postprocessing implemented in MATLAB. A 1.5T MR scanner employing a knee coil with $T2^*$ GRE (Gradient Recalled Echo) pulse sequence were used throughout the experiments. Various subjects such as water phantom, orange, and agarose gel phantom were used for the assessment of the self-developed PU algorithm. The MR temperature mapping experiment was initially attempted on the agarose gel phantom only with the application of a custom-made thermoregulating water pump as the heating source. Heat was generated to the phantom via hot water circulation whilst temperature variation was observed with T-type thermocouple. The PU program was implemented on the reconstructed wrapped phase images prior to map the temperature distribution of subjects. As the temperature change is directly proportional to the phase difference map, the absolute temperature could be estimated from the summation of the computed temperature difference with the measured ambient temperature of subjects. Results : The PU technique successfully recovered and removed the phase wrapping artifacts on MR phase images with various subjects by producing a smooth and continuous phase map thus producing a more reliable temperature map. Conclusion : This work presented a rapid, and robust self-developed center array-sequencing PU algorithm feasible for the application of MR temperature mapping according to the PRF phase shift property.

• Journal of the Korean Society for Precision Engineering
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• v.26 no.3
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• pp.137-143
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• 2009

It has been reported that mechanical stimulation takes a role in improving eel/ growth in skeletal system. Various research groups have been showed their own bioreactors which stimulate cell-seed three-dimensional scaffold. In this study, we hypothesized that the various conditions of mechanical stimulation would affect cell growth and proliferation. To prove our hypothesis, we designed a custom-made bioreactor capable of applying controlled compression to cell-encapsulated scaffolds. This device consisted of a circulation system and a compression system. Each parts of the bioreactor was fabricated using the rapid prototyping technology By using the rapid prototyping technology, we can modify and improve the bioreactor very rapidly For dynamic cell-culture, cell-encapsulated agarose gel was fabricated in 2% concentration. We performed dynamic cell-culture using this agarose gel and developed bioreactor in 3 days.

• Investigative Magnetic Resonance Imaging
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• v.15 no.1
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• pp.48-56
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• 2011

Purpose : The aim of this study is to measure the typical MR variables such as $T_1$- and $T_2$-relaxation times according to morphological characteristics of gold nanopartides as a preliminary study to perform theragnosis using local heating by gold nanopartides. Materials and Methods : Two types of gold nanoparticles were used. Spheres were synthesized by various methods and stirring speed. Rods were synthesized by adding various concentrations of sphere nanopartides. Gold nanopartides were mixed with 2% agarose gel at 1:1 ratio and then signals were acquired using a 1.5T MRI. For the measurements of $T_1$-and $T_2$-relaxation times, TR and TE were varied, respectively. The results were acquired through $T_1$ and $T_2$ curves based on the intensities of MR image using self-developed software. And Statistical analysis was performed. Results : $T_1$ times were measured 1.86 sec and 2.08 sec for sphere and rod, respectively. On the other hands, $T_2$ times were measured 57 ms and 35.45 ms for sphere and rod. Conclusion : The changes of the MR variables according to the morphological characteristics of the gold nanopartides were confirmed. Optimal MR imaging conditions can be obtained by choosing proper TR and TE according to the type of nanoparticles.

• Microbiology and Biotechnology Letters
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• v.33 no.1
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• pp.29-34
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• 2005

Lipase-producing bacteria (S3) were isolated from intertidal flat at Saemanguem. A isolated strain was identified as Psychrobacter species by physiological and fermentational characterization as well as 16S rRNA analysis. The strain was then named as Psychrobacter sp. S3. P. sp. S3 grew most rapidly at $30^{\circ}C$, but grew well even at $10^{\circ}C$ and its lipase activity was most high when cultivated at $20^{\circ}C$. Lipase S3 had optimum temperature of $30^{\circ}C$ for the hydrolysis of p-nitrophenyl caproate and had more than $80^{\circ}C$ activity even at $10^{\circ}C$. The activation energy was calculated to be 1.5 kcal/mol, which showed that it was a typical cold-adapted enzyme. It was an alkaline enzyme with optimum pH of $9.0\~9.5$. It could hydrolyze various length of triglycerides. Among them, it hydrolyzed most rapidly $C_4,\;C_{14},\; C_{16}-length$ triglycerides. When added to tributyrin-agarose gel, lipase S3 hydrolyzed tributyrin most rapidly at 30 and $40^{\circ}C$, but it could hydrolyze well even at $4^{\circ}C$.

• Journal of the Korean Society of Radiology
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• v.13 no.1
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• pp.55-63
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• 2019

It was reported that there were some cases in which signal was not inhibited but high signal appeared in cerebrospinal fluid on FLAIR(fluid attenuated inversion recovery) of MRI(Magnetic Resonance Imaging) in case a person inhales high-concentration oxygen. This study was to prepare basic database. We produced a phantom fixed with agar gel and by using it, obtained the images of the signals of normal saline into which oxygen was injected and normal saline diluted with contrast media by changing the TI(Inversion Time) of FLAIR technique and analyzed them. In the result of FLAIR technique of MRI using Philips Achieva MR 3.0T in Busan P Hospital, the SNR(Signal to Noise Ratio) of normal saline into which oxygen was injected was higher than the SNR of normal saline into which oxygen was not injected. However, it was not higher than the SNR of normal saline diluted with contrast media. In the TI 1,800ms, we could obtain the images which do not have the rise of the signal due to oxygen. In the CNR(Contrast to Noise Ratio) of normal saline into which oxygen was injected and normal saline diluted with contrast media as well, it was higher in the TI 1,800ms than in the TI 2,800ms that is mainly used clinically. It is thought that the result of this study could be basic database for studies on change of signal of cerebrospinal fluid as a result of injection of oxygen in FLAIR technique of MRI.