• Transactions of the Korean Society of Mechanical Engineers A
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• v.34 no.9
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• pp.1137-1143
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• 2010

This paper presents a fatigue design method for plug- and ring-type gas-welded joints, which takes into account the effects of welding residual stress. To develop this method, we simulated the gas-welding process by performing nonlinear finite element analysis (FEA) To validate the FEA results, numerically calculated residual stresses in the gas welds were then compared with experimental results obtained by the hole-drilling method. To evaluate the fatigue strength of plug- and ring-type gas-welded joints influenced by welding residual stresses, the use of stress amplitude $(\sigma_a)_R$, which includes the welding residual stress in gas welds, is proposed $(\sigma_a)_R$ on the basis of a modified Goodman equation that includes the residual stress effects. Using the stress amplitude $(\sigma_a)_R$ at the hot spot point of gas weld, the relations obtained as the fatigue test results for plug and ring type gas welded joints having various dimensions and shapes were systematically rearranged to obtain the $(\sigma_a)_R-N_f$ relationship. It was found that more systematic and accurate evaluation of the fatigue strength of plug- and ring-type gas-welded joints can be achieved by using $(\sigma_a)_R$.

• The Journal of Korean Academy of Prosthodontics
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• v.40 no.6
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• pp.545-559
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• 2002

There has been increasing use of IPS Empress $2^{(R)}$ owing to easy fabrication method, high esthetics similar to natural teeth, good marginal accuracy, and sufficient fracture strength. However, in clinical application, although a luting agent and the tooth cementation bonding procedure influence the marginal accuracy and fracture strength restoration, there has been a controversy in the selection of proper luting agent. This study was to measure the marginal fidelites and fracture strength of IPS Empress crowns according to three cement types, Protec $cem^{(R)}$, Variolink $II^{(R)}$ and Panavia $21^{(R)}$. After construction of 12 experimental dies for each group, IPS Empress $2^{(R)}$ crowns were fabricated and luted the metal master die prepartion of the maxillary right premolar. Marginal gaps before cementation and after cementation were measured. Buccal incline on the functional cusp of specimens were loaded until the catastrophic failure and fracture strength was measured. The results of this study were as follows: 1. The range of gap was $34.04{\pm}4.84{\mu}m$ before cementation and $37.88{\pm}5.00{\mu}m$ after cementation, which showed significant difference by paired t-test (p<0.05). The difference in the results from marginal accuracy according to measuring point proved to be not statistically significant by two-way ANOVA test (p>0.05). 2. The difference in the results from marginal accuracy according to three cement types Proved that The Variolink $II^{(R)}$ cement group had the least gap, $35.43{\pm}5.03{\mu}m$, and showed superior marginal accuracy while there existed statistic significance in Protec $cem^{(R)}$ cement group, $39.06{\pm}4.41{\mu}m$ or Panavia $21^{(R)}$ cement group, $39.16{\pm}4.39{\mu}m$ by two-way ANOVA test & multiple range test (p<0.05). 3. The difference in the results from fractures strength testing according to three cement type groups proved to be statistically significant (p<0.05). The Variolink $II^{(R)}$ cement group shows highest fracture strength of $1257.33{\pm}226.77N$, Panavia $21^{(R)}$ cement group has $1098.08{\pm}138.45N$, and Protec $cem^{(R)}$ cement group represents the lowest fracture strength of $926.75{\pm}115.75N$. 4. Three different cement groups of different components showed acceptable marginal fidelity and fracture strength. It is concluded that IPS Empress $2^{(R)}$ crowns luted using Variolink $II^{(R)}$ cement group had stronger fracture strength and smaller marginal gap than the other cement groups. Although Variolink $II^{(R)}$ resin cement seemed acceptable to clinical applications in IPS Empress $2^{(R)}$ system, the IPS Empress $2^{(R)}$ system still requires long-term research due to the lack of data in clinical applications.

• Bulletin of the Korean Chemical Society
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• v.35 no.4
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• pp.1082-1086
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• 2014

A multi-channel microchip electrophoresis (MCME) method with parallel laser-induced fluorescence (LIF) detection was developed for rapid screening of H1N1 virus. The hemagglutinin (HA) and nucleocapsid protein (NP) gene of H1N1 virus were amplified using polymerase chain reaction (PCR). The amplified PCR products of the H1N1 virus DNA (HA, 116 bp and NP, 195 bp) were simultaneously detected within 25 s in three parallel channels using an expanded laser beam and a charge-coupled device camera. The parallel separations were demonstrated using a sieving gel matrix of 0.3% poly(ethylene oxide) ($M_r$ = 8,000,000) in $1{\times}$ TBE buffer (pH 8.4) with a programmed step electric field strength (PSEFS). The method was ~20 times faster than conventional slab gel electrophoresis, without any loss of resolving power or reproducibility. The proposed MCME/PSEFS assay technique provides a simple and accurate method for fast high-throughput screening of infectious virus DNA molecules under 400 bp.

• Asian-Australasian Journal of Animal Sciences
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• v.10 no.6
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• pp.671-678
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• 1997

The objective was to evaluate method of feeding (free access or intubation), method of slaughter (carbon dioxide gas or barbiturate) and digesta flushing medium (distilled water or physiological saline), in the development of an ileal amino acid digestibility assay for 4 week-old broiler chickens. Three diets were used (commercial (C), semi-synthetic meat-and bone meal (MBM) or wheat (W)). For the coarser C and W diets but not for the MBM diet, feeding method had a significant effect on concentrations of chromium (Cr), nitrogen (N), acid detergent fibre (ADF) and neutral detergent fibre (NDF) in the crop contents at a set time after a meal. There appeared to be a selection of food particles under free-access feeding. For birds receiving the wheat diet there was an effect (p < 0.05) of sampling time after feeding on the concentrations of Cr, N, ADF and NDF/Cr in the crop contents. Flushing ileal digesta with distilled water or saline led to similar apparent ileal N digestibility coefficients. Birds given the MBM diet, and killed by inhalation of $CO_2$, had significantly (p < 0.05) lower apparent ileal N digestibility coefficients (73 versus 80%) than those killed by barbiturate overdose.

• Applied Chemistry for Engineering
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• v.10 no.5
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• pp.796-803
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• 1999

Solution copolymerization of styrene(St.) with methyl methacrylate(MMA), ethyl methacrylate(EMA) and n-butyl methacrylate(BMA) was carried out with benzoylperoxide(BPO) as an initiator in toluene at $80^{\circ}C$ in a continuous stirred tank reactor. Reaction volume and residence time were 0.6 liters and 3hours, respectively. The monomer reactivity ratios, $r_1(St.)$ and $r_2(RMA)$ determined by both the Kelen-Tudos method and the Fineman-Ross method were $r_1(St.)=0.60(0.61),\;r_2(MMA)=0.59(0.60);\;r_1(St.)=0.65(0.62),\;r_2(EMA)=0.55(0.52);\;r_1(St.)=0.75(0.67),\;r_2(BMA)=0.63(0.56)$. The cross-termination factor $\Phi$ of the copolymer over the entire St. compositions ranged from 0.26 to 0.96. The $\Phi$ factors of St.-RMA copolymer were increased with increasing St. content. The simulated conversions and copolymerization rates were compared with the experimental results. The average time to reach dynamic steady-state was three times and half of the residence time.

• Bulletin of the Korean Chemical Society
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• v.6 no.1
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• pp.3-7
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• 1985

The general formulas for SCF atomic orbitals |5s > and |6p > have been derived separately by expressing the spherical harmonics part in terms of the coordinate($r_1,\;$r_2$) of the reference point, and by translating the exponential part, $r^4\;exp\;(-{\beta}r)$), in terms of $r_1,\;and\;r_2$ and the modified Bessel functions. Master formulas for overlap and dipole moment matrix elements are derived. The computed values of overlap and dipole moment matrix elements for hypothetical NO molecule are exactly in agreement with those for the previous methods.

• Bulletin of the Korean Chemical Society
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• v.18 no.2
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• pp.193-197
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• 1997

Theoretical studies on the base-catalyzed deprotonation of 4-phenacylpyridinium cations, R1-CO-CH2-C5H4N-R2, I (R1=YC6H4 -and R2=CH3), and II (R1=C6H5 and R2=CH2C6H4Y) have been carried out with bases, NH3 and XC6H4NH2 using AM1 MO method. The Brψnsted α values are 0.20 and 0.22 and the βB values are 0.62 and 0.61, respectively for cations I and II. The negative Ⅰ (=α-βB) values obtained are in accord with the experimental results in aqueous solution, although the theoretical gas-phase α values for I are somewhat smaller than the experimental values in water due to neglect of solvation effect. It has been stressed that the Brψnsted α is distorted not only by the lag in the resonance and solvation development in the carbanion, but also by the difference in the distance between the anionic center and substituents in the TS and in the product anion.

• Archives of Pharmacal Research
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• v.21 no.5
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• pp.521-526
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• 1998

The physicochmical properties of recombinant hepatitis B surface antigen (r-HBsAg), which was expressed in C127 mammalian cell were studied. Using roller bottle culture in DMEM supplemented with fetal bovine serum, 10-15 mg/L of r-HBsAg was produced with about 31% of purification yield. The purity of r-HBsAg by HPLC was 99.8% and electron microscopic examination showed homogeneous spherical particle with 22 nm in diameter, a morphological characteristic of HBsAg. The density of r-HBsAg by CsCI density gradient method was 1.19g/ml and the isoelectric point by Mono $P^{TM}$ HR 5/20 column was 4.6. The analysis of subunit protein pattern using SDS-PAGE followed by scanning densitometry gave 81.3% of S protein and 18.7% of pre-S protein. fluorophore-assisted-carbohydrate-electrophoresis analysis showed the relative amount of carbohydrate to protein was 1.7% and it smajr component was N-acetyl glucosamine, which was about 39% of total carbohydrate. The relative amount of lipid to protein determined by vanillin phosphoric acid method was 32.5% and its major component was phospholipid, which was about 70% of total lipid. The physicochemical properties of C127 mammalian cell-derved r-HBsAg are similar to those of p-HBsAg, suggesting that the r-HBsAg can be used in developing a new preventive vaccine against hepatitis B.

• Journal of KIISE
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• v.41 no.10
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• pp.792-798
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• 2014

In spatial databases, R-tree is one of the most widely used indexing structures and many variants have been proposed for its performance improvement. Among these variants, Hilbert R-tree is a representative method using Hilbert curve to process large amounts of data without high cost split techniques to construct the R-tree. This Hilbert R-tree, however, is hardly applicable to large-scale applications in practice mainly due to high pre-processing costs and slow bulk-load time. To overcome the limitations of Hilbert R-tree, we propose a novel approach for parallelizing Hilbert mapping and thus accelerating bulk-loading of Hilbert R-tree on GPU memory. Hilbert R-tree based on GPU improves bulk-loading performance by applying the inversed-cell method and exploiting parallelism for packing the R-tree structure. Our experimental results show that the proposed scheme is up to 45 times faster compared to the traditional CPU-based bulk-loading schemes.

• Journal of Chest Surgery
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• v.36 no.7
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• pp.489-496
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• 2003

To clarify the prognostic implication of the location and number of the metastatic mediastinal nodes in resected stage IIIA N2 non-small cell lung cancer. Material and Method: One hundred and seventy-four patients with resected non-small cell lung cancer who eventually proved to have pathologic stage IIIA N2 disease were studied. Patients who received preoperative induction therapy, non-curative operation or defined as operative mortality were excluded from this study. Result: In upper lobe tumors, there was no difference in 5-year survival according to the involvement of lower mediastinal nodes (32.3% vs 25.6%, p＝0.86). In lower lobe tumors, no difference was found in 5-year survival according to the involvement of upper mediastinal nodes (25.1% vs 14.1%, p＝0.33). There was no significant difference in 5-year survival between patients with or without metastatic subcarinal node (20.9% vs 25.6%, p＝0.364). In terms of the number of metastatic mediastinal nodes, 5-year survival was better in single station group (26.3%) than multiple station group (18.3%) (p＝0.048). In multiple station N2 group, the patients who received postoperative chemotherapy and radiation therapy had better 5-year survival (34.2%) (p＝0.01). Cox's proportional hazards model revealed that the age $\geq$60 (O.R: 1.682, p＝.006), multiple station N2 (O.R: 1.503. p＝0.021), pneumonectomy (O.R: 1.562, p＝0.018), postoperative chemotherapy and radiation therapy (O.R: 0.625, p＝0.012) were the factors affecting the postoperative survival. Conclusion: Multiple station N2 disease was the important prognostic factor for postoperative survival in resected stage IIIA N2 non-small cell lung cancer. Postoperative chemotherapy and radiotherapy were thought to improve the survival in case of multiple station N2 disease.