• Journal of Korean Foot and Ankle Society
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• v.24 no.4
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• pp.142-147
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• 2020

Purpose: Diabetic foot ulcers are closely related to body surface heat, which can be affected easily by temperature differences. This study examined the correlation between the healing process of diabetic wounds and abnormal diurnal temperature through an animal study. Materials and Methods: Rats in the abnormal diurnal temperature group and control group were given a 10 mm sized full-thickness skin ulcer. Wound size progression was observed in both groups. H&E and Masson's trichrome staining was performed at 14 days after wound formation, and the number of vessels per unit area and histology analysis were performed. The changes in the ulcer were measured through three dimensional cross-section area using INSIGHT^® devices. Results: The wound recovery period (granulation ingrowing) was 24 days in the abnormal diurnal temperature model and 20 days in the control group. The thickness of scar tissue was 402±23.19 ㎛ in the control group and 424.5±36.94 ㎛ in the diurnal temperature model. Neovascular formation was counted as 5.1±0.97 for the control group and 4.16±0.94 for the diurnal temperature model group. Conclusion: Delayed and inferior diabetic wound healing was observed in the abnormal diurnal temperature group, which was characterized by greater diurnal variations than the typical growth environment.

• Plant Journal
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• v.17 no.3
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• pp.42-46
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• 2021

The equation of motion of the drill string along the excavation trajectory was analyzed using the Lagrangian approach together with the finite element method (FEM). A drill string of circular cross section is constructed by combining a plurality of circular axes each having 12 degrees of freedom (DOF). FEM analysis can observe the vibration and dynamic changes of the entire drill string, and it is easy to apply comprehensive boundary conditions to reproduce the simulation of a realistic drill string. In this study, the constructed FEM motel was simulated. In order to apply the FEM program to the actual drill trajectory, the dynamic analysis of the curved beam was verified by comparison with the actual values. The dynamic change over time was observed.

• Nuclear Engineering and Technology
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• v.53 no.3
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• pp.949-959
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• 2021

The current study aims to explore the shielding properties of multi-component borate-based glass series. Seven glass-samples with composition of (80-y)H₃BO₃-10ZnO-10Na₂O-yBaO where (y = 0, 5, 10, 15, 20, 25 and 30 mol.%) were synthesized by melt-quench method. Various shielding features for photons, neutrons, and protons were determined for all prepared samples. XCOM, Phy-X program, and SRIM code were performed to determine and explain several shielding properties such as equivalent atomic number, exposure build-up factor, specific gamma-ray constants, effective removal cross-section (Σ_R), neutron scattering and absorption, Mass Stopping Power (MSP) and projected range. The energy ranges for photons and protons were 0.015-15 MeV and 0.01-10 MeV, respectively. The mass attenuation coefficient (μ/ρ) was also determined experimentally by utilizing two radioactive sources (¹⁶⁶Ho and ¹³⁷Cs). Consistent results were obtained between experimental and XCOM values in determining μ/ρ of the new glasses. The addition of BaO to the glass matrix led to enhance the μ/ρ and specific gamma-ray constants of glasses. Whereas the remarkable reductions in Σ_R, MSP, and projected range values were reported with increasing BaO concentrations. The acquired results nominate the use of these glasses in different radiation shielding purposes.

• Korean Journal of Optics and Photonics
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• v.32 no.5
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• pp.230-234
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• 2021

Relief of thermal stress has received great attention, to improve the beam quality and stability of high-power laser diodes. In this paper, we investigate a microtrench structure engraved around a laser-diode chip-on-submount (CoS) to relieve the thermal stress on a laser-diode bar (LD-bar), using the SolidWorks® software. First, we systematically analyze the thermal stress on the LD-bar CoS with a metal heat-sink holder, and then derive an optimal design for thermal stress relief according to the change in microtrench depth. The thermal stress of the front part of the LD-bar CoS, which is the main cause of the "smile effect", is reduced to about 1/5 of that without the microtrench structure, while maintaining the thermal resistance.

• KOREAN JOURNAL OF PACKAGING SCIENCE & TECHNOLOGY
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• v.27 no.2
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• pp.55-62
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• 2021

This study aims to reduce the rancid odor generated during the fermentation process of kimchi by inserting zinc oxide (ZnO) into an inorganic porous material with a high surface area to decompose or adsorb the fermentation odor. ZnO activated by the presence of moisture exhibits decomposition of rancid odors. Mixed with Titanium dioxide (TiO₂), a photocatalyst. To manufacture the packaging liner used in this study, NaOH, ZnCl₂, and TiO₂ powder were placed in a tank with diatomite and water. The sludge obtained via a hydrothermal ultrasonication synthesis was sintered in an oven. After being pin-milled and melt-blended, the powders were mixed with linear low-density polyethylene (L-LDPE) to make a masterbatch (M/B), which was further used to manufacture liners. A gas detector (GasTiger 2000) was used to investigate the total amount of sulfur compounds during fermentation and determine the reduction rate of the odor-causing compounds. The packaging liner cross-section and surface were investigated using a scanning electron microscope-energy dispersive X-ray spectrometer (SEM-EDS) to observe the adsorption of sulfur compounds. A variety of sulfur compounds associated with the perceived unpleasant odor of kimchi were analyzed using gas chromatography-mass spectrometry (GC-MS). For the analyses, kimchi was homogenized at room temperature and divided into several sample dishes. The performance of the liner was evaluated by comparing the total area of the GC-MS signals of major off-flavor sulfur compounds during the five days of fermentation at 20℃. As a result, Nano-grade inorganic compound liners reduced the sulfur content by 67 % on average, compared to ordinary polyethylene (PE) foam liners. Afterwards SEM-EDS was used to analyze the sulfur content adsorbed by the liners. The findings of this study strongly suggest that decomposition and adsorption of the odor-generating compounds occur more effectively in the newly-developed inorganic nanocomposite liners.

• Journal of the Korean Wood Science and Technology
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• v.49 no.1
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• pp.67-81
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• 2021

This study aimed to conduct tree-ring dating and analysis of the materials used for the wooden coffins excavated from the ruins of Sipjeong-dong, Incheon. The tree species for the 10 wooden coffin materials was identified as pine. For accurate tree-ring measurement, the cross section was polished using sandpaper. The annual ring width was measured with an accuracy of 0.01 mm. Since the five materials were consistent with each other in dendrochronology, a representative annual ring chronology of 83 years was prepared. The prepared representative annual ring chronology was compared with the standard annual ring chronology, and the outermost ring of the wooden coffin was confirmed to correspond to the year 1575, suggesting that the wooden coffin was produced in the late 16th century. In addition, microscopic observation and FT-IR analysis revealed that the fibers attached to the surface of the wooden coffin were fibroin (Silk), and infrared spectroscopy (FT-IR) and Py-GC/MS analysis showed that the paint left on the surface of the wooden coffin was lacquer.

• Journal of the Architectural Institute of Korea Structure & Construction
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• v.33 no.12
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• pp.37-44
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• 2017

Due to structural characteristics, construction costs and duration of a modular system would be saved by minimizing the schedule on the job site. As such, it is crucial to develop a connection that can guarantee stiffness while allowing for simple assembling. Particularly, the mid- to high-rise construction of the modular system necessitates the securing of the structural stability and seismic performance of multi-unit frames and connections, and thus, the stiffness of unit-assembled structures needs to be re-evaluated and designed. However, evaluating a frame consisting of slender members and reinforcing materials is a complicated process. Therefore, the present study aims to examine the structural characteristics of a modular unit connection based a method for reinforcing connection brackets and hinges while minimizing the loss of the cross section. Toward this end, the study modeled the beam-to-column connection of a modular system with the proposed connection, and produced a specimen which was used to perform a cycling loading test. The study compared the initial stiffness, the attributes of the hysteretic behavior, and the maximum flexural moment, and observed whether the model acquired the seismic performance, compared to the flexural strength of the steel moment frame connection that is required by the Korean Building Code. The test results showed that the proposed connection produced a similar initial stiffness value to that of the theoretical equation, and its maximum strength exceeded the theoretical strength. Furthermore, the model with a larger ceiling bracket showed higher seismic performance, which was further increased by the reinforcement of the plate.

• Advances in concrete construction
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• v.11 no.5
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• pp.375-386
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• 2021

In this paper, a study of stability and health of a newly-built railway tunnel is presented. The field test was implemented to monitor the secondary lining due to the significant cracking behaviors influenced the stability and health of the tunnel structure. Surface strain gauges were installed for monitoring the status of crack openings, and the monitoring outputs demonstrated that the cracks were still in the developing stage. Additionally, adjacent tunnel and poor condition of surrounding rock were identified as the causes of the lining cracking by systematically characterizing the crack spatial distribution, tunnel site and surrounding rock conditions. Reconstruction of partial lining and reconstruction of the whole secondary lining were designed as the maintenance projects for different cracking regions based on the construction feasibility. For assessing the health conditions of the reinforced lining, embedded strain gauges were set up to continuously measure the strain and the internal force of the reconstructed structures. For the partially reconstructed lining, the outputs show the maximum tensile elongation is 0.018 mm during 227 days, which means the structure has no obvious deformation after maintenance. The one-year monitoring of full-section was implemented in the other two completely reconstructed cross-sections by embedded strain gauge. The outputs show the reconstructed secondary lining has undertaken the pressure of surrounding rock with the time passing. According to the calculated compressive and tensile safety factors, the completely reconstructed lining has been in reliable and safe condition during the past year after reinforcement. It can conclude that the aforementioned maintenance projects can effectively ensure the stability and health of this tunnel.

• PNF and Movement
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• v.12 no.4
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• pp.243-248
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• 2014

Purpose: The transverse abdominis and themultifidus muscle are located in the core. They surround one's trunk and help in body stabilization. Specifically, they control spine articulation to maintain posture and balance. Therefore, weakened deep muscle in the trunk may cause spinal malalignment. This study aims to compare the correlation between the thickness of the transverse abdominis and the multifidus muscle and the spine alignment among college students in their 20s. Methods: This study measured the thickness of the transverse abdominis and the multifidus muscle of 42 healthy college students in their 20s using ultrasonic waves. The thickness of the muscle was measured for the length of the cross-section except for fascia. The thickness of the left and right muscles was measured, and the mean value was calculated. As the thickness of the transverse abdominis can increase because of pressure during exhalation, it was measured at the last moment of exhalation. Spinal alignment was measured by the kyphosis angle, lordosis angle, pelvic tilt, trunk inclination, lateral deviation, trunk imbalance, and surface rotation using Formetric III, which is a three-dimensional imaging equipment. They were measured for three times, and the mean values were calculated. The general characteristics of the subjects were analyzed using descriptive statistics. The correlations between each factor were analyzed using Pearson's correlation analysis. Results: The transverse abdominis showed asignificant correlation with trunk inclination (p<.05). The multifidus muscle showed a significant positive correlation with pelvic tilt and a negative correlation with surface rotation (p<.05). Conclusion: The thickness of transverse abdominis and the multifidus muscle appears to influence spinal alignment. Specifically, the multifidus muscle, which plays an important role on the sagittal plane, influences surface rotation, thus making it an important muscle for scoliosis patients. Therefore, a strengthening training program for the transverse abdominis and the multifidus muscle is necessary according to specific purposes among adults with spinal malalignment.

• Journal of Environmental Health Sciences
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• v.47 no.3
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• pp.227-244
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• 2021

Objectives: The Korean National Environmental Health Survey provides representative biomonitoring data for environmental pollutants in South Korea. Over the last decade, there have been various studies published using this data. In this study, we aimed to provide information and implications by reviewing each study. Methods: We searched comprehensive electronic databases from PubMed, Google Scholar, and Naver Academic database using the key words 'Korean National Environmental Health Survey' and 'KoNEHS' through March 2021. A total of 57 studies were selected after reviewing the relevance of the data. Results: The most frequently studied pollutants were heavy metals (10), Cotinine (8), Bisphenol A (7), and Phthalates (6), in that order. In particular, Phthalates, Bisphenol A, and Parabens were often studied together (6). A decline in urinary cotinine and heavy metals in the body was shown over time among studies on exposure association. It was demonstrated that Phthalates and Bisphenol A were significantly related to obesity and diabetes from the studies of health impacts. Cross-section study design, spot urine, and insufficient health status information were mostly reported as limitations of the data. Conclusion: Since research has been focused on adults, further investigations of children and adolescents are required. In this regard, it is necessary to maintain the consistency of the data structure and provide integrated weights for all ages. In addition, it would allow the measurement of several environmental pollutants by considering subsample design. Lastly, integrated studies with multi-cycles and the health effects from co-exposure to multiple chemicals would be expected to provide important knowledge.