• Journal of Korean Ophthalmic Optics Society
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• v.11 no.3
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• pp.225-229
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• 2006

In our angle configuration, several peculiar characteristic behaviors of MR could be observed, the mixing of positive MR(PMR) and negative MR(NMR) in the inclined sample was observed. The complete mixing angle, ${\phi}_{mix}$ as a function of inclination angle, ${\theta}$ was observed to fit well to the relation of ${\phi}_{mix}=tan^{-1}(1+tan{\theta})$ in nickel films. The above theoretical relation was obtained by decomposing the magnetic field into the components parallel and perpendicular to the current flow and identifying ${\phi}_{mix}$ as the angle satisfying that the above two components of magnetic field were identical. We also observed that the data of ${\phi}_{mix}$ did not satisfy the above theoretical relation in the iron film. This was explained by the fact that the growth direction in the iron film was an intermediate direction of magnetization, while the growth direction in the nickel film was an easy axis of magnetization.

• Journal of Korea Foresty Energy
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• v.17 no.1
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• pp.36-46
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• 1998

The aim of this study was to develop the noise and vibration damping wood-based composites by using viscoelastic polymer materials. Polyvinylchloride(PVC) was plasticized with 20-140 phr bis(2-ethylhexyl) phthalate(DOP) and the dynamic tensile mechanical properties were measured at 110Hz and approximate temperature range -100 to 150$^{\circ}$ using a Rheovibron Instrument. The PVC/DOP blends were shown to be compatible in all proportions, and both T(E”$_{max}$) and T(tan${\delta}_{max}$) shifted to the lower temperature side as the DOP content increased. The vibration damping properties of wood/polymer composites were measured using the Rheovibron instrument in a bending mode. The composite damping factor(tan ${\delta}_{c}$) of wood /PVC-DOP/wood sandwich structure correlated with the loss factor and that of the coated structure correlated with the loss modulus(E”) of the polymer layer. In addition, the sandwich structure was found to be more effective in damping than the coated structure. The logarithmic decrement (${\Delta}$c) curve of a sandwich structure, which was determined by the free-free flexural vibration method was similar in shape to the tan ${\delta}_{c}$ curve.

• KSBB Journal
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• v.13 no.3
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• pp.238-243
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• 1998

Nitrifier consortium immobilized in Ca and Ba-alginate beads were packed into two bioreactors and the performances of bioreactors were evaluated for the removal of ammonia nitrogen from synthetic aquaculture water. The total ammonia nitrogen (TAN) concentration of the influent was continually kept about 2g TAN/㎥. At the HRT of 0.6hr, ammonia nitrogen removal rate of two bioreactors were about 52.6 and 51.0g TAN/$\textrm{m}^3$/day, respectively. At the respect of ammonia nitrogen removal, two bioreactor showed the similar abilities. The second trial with nitrifier consortium immobilized in Ca-alginate bead was carried out to evaluate the ammonia nitrogen removal rate for 35 days. The highest ammonia nitrogen removal rate was 82g TAN/$\textrm{m}^3$ when HRT was about 0.3hr.

• Clinics in Shoulder and Elbow
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• v.20 no.4
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• pp.183-188
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• 2017

Background: To evaluate the clinical outcomes and associated repair integrity in patients treated with arthroscopic repair for a transtendinous rotator cuff tear followed by resection of the remnant rotator cuff tendon. Methods: Between July 2007 and July 2011, we retrospectively reviewed patients who were treated for transtendinous full-thickness tears in the tendinous portion of the rotator cuff by arthroscopic repair. Clinical outcomes were evaluated using the American Shoulder and Elbow Surgeons (ASES) score, the Shoulder Rating Scale of the University of California at Los Angeles (UCLA), the Constant-Murley score, a visual analogue scale (VAS) pain score, and range of motion (ROM). The repair integrity was determined by magnetic resonance imaging or ultrasonography. Results: There were 19 shoulders with transtendinous full-thickness tears in the tendinous portion of the rotator cuff. The ASES, UCLA, Constant-Murley, and VAS pain scores showed significant improvements in function and symptoms (all p<0.001). The active ROM for forward flexion and abduction was also significantly improved (p=0.002 and p<0.001, respectively). The postoperative radiological examination showed cuff integrity without a re-tear in 68.4% of patients. However, the UCLA, ASES, and Constant-Murley scores were not significantly different between healed and re-torn group (p=0.530, p=0.885, and p=0.262, respectively). Conclusions: Although repair of transtendinous rotator cuff tears followed by resection of the remnant rotator cuff tendon in the footprint has a relatively high re-tear rate, no significant difference was observed in the short-term clinical results between the re-tear and healed groups.

• Journal of the Korean Society of Environmental Restoration Technology
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• v.20 no.6
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• pp.107-115
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• 2017

This study illustrated the process of bar structure and vegetation coverage to understand historical changes of riverbed and suppose adaptive management in Tan-chun ecological landscape reserve. The study site that lower reach of the Tan-chun are known as habitats of migratory bird and aquatic species with dynamic riverbed. Aerial photos from 2006 to 2016 and surveyed vegetation data in 2006 and 2016 were used by analysis of landscape changes and comparison of vegetation coverage. Study area is classified into 3 sites (A: straight site, B: meandering site, C: meandering and junction with Yangjae-cheon). The result showed that bar area of A and C sites gradually increased, B site decreased during 10 years. Also, ratio of bar area to vegetation coverage and level of vegetation coverage increased in all sites during 10 years. All sites seem to have experienced the terrestrialization with time. On the other hand, ratio of annual vegetation increased and ratio of perennial vegetation decreased in C site in 2016 compare to 2006. Because area of Japanese Hops (Humulus japonicas) as one type of annual vegetation increased, other vegetation could not grow up by its powerful expandability. It is time to make active adaptive management based on not only continuos monitoring but also revaluation of river conditions in order to enhance habitat quality and quantity in Tan-chun ecological landscape reserve.

• Fisheries and Aquatic Sciences
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• v.7 no.2
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• pp.76-83
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• 2004

To supply fresh and quality quarantined seafood in live seafood specialty restaurants, facilities for short-term culture or holding of live marine fish and shellfish are a necessity. In this study, the performance of a simple recirculating aquarium system for the culture and holding of marine fish was evaluated. The aquarium system consisted of a culture tank, a foam fractionator for solids removal, and a Styrofoam bead filter for nitrification and solids trapping. In the first trial, the aquarium was stocked with a total of 12 kg Korean rockfish, which were fed approximately $0.5\%$ of the total fish body weight daily. During the 2-month culture period, total ammonia nitrogen (TAN) and nitrite nitrogen $(NO_2-N)$ concentrations remained below 1mg/L and 2mg/L, respectively. The chemical oxygen demand (COD) fluctuated between 13.6 and 31.2 mg/L on selected sampling days. The total suspended solids (TSS) removed by the foam fractionator was between 2.7 and 4.6g daily. The Styrofoam bead filter not only reduced TAN and $NO_2-N$ in the culture tank water, but also trapped solids equivalent to 8.3-26.7\% of the weight of feed supplied. In Trial 2, 30kg of live fish were held in the aquarium without feeding for a 24-hour period and the water quality parameters were monitored. TAN and $NO_2-N$ concentrations first increased and then decreased to around 0.3mg/L. These results demonstrate that the recirculating aquarium system is a functional option for the short-term culture or holding of marine fish.

• Asian Pacific Journal of Cancer Prevention
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• v.15 no.24
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• pp.10893-10898
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• 2015

Several molecular markers have been proposed as predictors of outcome in patients with glioblastomas. We investigated the prognostic significance of $O^6$-methylguanine-DNA methyltransferase (MGMT) promoter methylation and TP53 mutation status dependent on isocitrate dehydrogenase 1 (IDH1) mutation in glioblastoma patients. A cohort of 78 patients with histologically confirmed glioblastomas treated with radiation therapy and chemotherapy were reviewed retrospectively. We evaluated the prognostic value of MGMT promoter methylation and TP53 mutation status with regard to progression-free survival (PFS) and overall survival (OS). It was revealed that mutations in IDH1, promoter methylation of MGMT, TP53 mutation, age, Karnofsky performance status (KFS), and extension of resection were independent prognostic factors. In patients with an IDH1 mutation, those with an MGMT methylation were associated with longer PFS (p=0.016) and OS (p=0.013). Nevertheless, the presence of TP53 mutation could stratify the PFS and OS of patients with IDH1 wild type (p=0.003 and 0.029 respectively, log-rank). The MGMT promoter methylation and TP53 mutation were associated with a favorable outcome of patients with and without mutant IDH1, respectively. The results indicate that glioblastomas with MGMT methylation or TP53 mutations have improved survival that may be influenced by IDH1 mutation status.

• Journal of Electrical Engineering and Technology
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• v.6 no.3
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• pp.384-390
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• 2011

To evaluate the condition of stator winding insulation in generators that have been operated for a long period of time, diagnostic tests were performed on the stator bars of a 500 MW, 22 kV generator under accelerated thermal and electrical aging procedures. The tests included measurements of AC current (${\Delta}I$), dissipation factor ($tan{\delta}$), partial discharge (PD) magnitude, and capacitance (C). In addition, the AC current test was performed on the stator winding of a 350 MW, 24 kV generator under operation to confirm insulation deterioration. The values of ${\Delta}I$, ${\Delta}tan{\delta}$, and PD magnitude in one stator bar indicated serious insulation deterioration. In another stator bar, the ${\Delta}I$ measurements showed that the insulation was in good condition, whereas the values of ${\Delta}tan{\delta}$ and PD magnitude indicated an incipient stage of insulation deterioration. Measurements of ${\Delta}I$ and PD magnitude in all three phases (A, B, C) of the remaining generator stator windings showed that they were in good condition, although the ${\Delta}tan{\delta}$ measurements suggested that the condition of the insulation should be monitored carefully. Overall analysis of the results suggested that the generator stator windings were in good condition. The patterns of PD magnitude in all three phases (A, B, C) were attributed to internal discharge.

• Composites Research
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• v.30 no.6
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• pp.422-428
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• 2017

The moisture absorption behavior, tensile properties, and thermal analysis properties of MWCNT embedded nanocomposites exposed to temperature and moisture were evaluated. The contents of MWCNT were 0 wt%, 1 wt%, and 2 wt%, respectively. The specimens were exposed to immersed conditions at $25^{\circ}C$ and $75^{\circ}C$ for up to 600 hours. According to the results, the apparent moisture content increased as the exposure time increased, but the difference between the maximum moisture content and the moisture content at 600 hours was almost constant. The tensile modulus decreased with increasing exposure time and the degree of decrease was increased significantly as the MWCNT content and exposure temperature increased. The tensile strength decreased with longer exposure time without MWCNT, but increased with MWCNT due to the reinforcing effect of MWCNT. The storage modulus, glass transition temperature, tan d peak magnitude were low as the exposure time increased, but tan d curves with two peaks appeared when exposed to high exposure temperature for more than 300 hours.

• Applied Chemistry for Engineering
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• v.9 no.4
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• pp.608-613
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• 1998

The purpose of this experiment was the physical properties of rubber compounds with DPCB and pure carbon black. Si-O peak in the silcia surface was observed at the range of wavenumber from 1,100 to 1,200 in the DPCB by FT-IR analysis. Cure rate of rubber compounds containing DPCB and organic silane coupling agent were (Si69) delayed compared with those containing pure carbon black. 300% modulus and interaction coefficient of DPCB with silane coupling agent were higher than those of pure carbon black and PICO weight loss amount showed constant value. It was found that $0^{\circ}C$ tan$\delta$ of rubber compounds with DPCB was larger than those of pure carbon black at 2.0% silane coupling agent based on 50 phr DPCB and $60^{\circ}C$ tan$\delta$ of rubber compounds with DPCB decreased as increasing the usage coupling agent. Consequently, it is postulated that DPCB is strong candidate material for lowering rolling resistance under constant abrasion resistance.