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This study examines the impacts of copper and boron in parts per million (ppm) on the microstructure and mechanical properties of spheroidal graphite cast iron (SCI). Boron’s inclusion increases the ferrite content whereas copper augments the stability of pearlite. The interaction between the two significantly influences the ferrite content. Differential scanning calorimetry (DSC) analysis indicates that boron alters the enthalpy change of the α + Fe3C → γ conversion and the α → γ conversion. Scanning electron microscope (SEM) analysis confirms the locations of copper and boron. Mechanical property assessments using a universal testing machine show that the inclusion of boron and copper decreases the tensile strength and yield strength of SCI, but simultaneously enhances elongation. Additionally, in SCI production, the utilization of copper-bearing scrap and trace amounts of boron-containing scrap metal, especially in the casting of ferritic nodular cast iron, offers potential for resource recycling. This highlights the importance of resource conservation and recycling in advancing sustainable manufacturing practices. These findings provide critical insights into the effects of boron and copper on SCI’s behavior, contributing to the design and development of high-performance SCI materials.

This study investigated the impact of boron and copper on the microstructure and mechanical properties of Spheroidal graphite Cast Iron (SCI). The addition of boron increased the ferrite content, while copper increased the stability of pearlite. The interaction between boron and copper significantly increased the ferrite content. Differential Scanning Calorimetry (DSC) revealed that boron decreased the enthalpy change of the α + Fe3C -> γ transformation and increased the enthalpy change of the α -> γ transformation. The addition of boron and copper reduced the tensile and yield strength but increased elongation and impact energy. The findings provide valuable insights into the effect of boron and copper on SCI, facilitating the design and development of high-performance SCI materials.

To evaluate the dynamic characteristics at all positions of the main spindle of a machine tool, an experimental point was selected using a full factorial design, and a vibration test was conducted. Based on the measurement position, the resonant frequency was distributed from approximately 236 to 242 Hz. The approximation model was evaluated based on its resonant frequencies and dynamic stiffness using regression and interpolation methods. The accuracy of the resonant frequency demonstrated by the kriging method was approximately 89%, whereas the highest accuracy of the dynamic stiffness demonstrated by the polynomial regression method was 81%. To further verify the approximation model, its dynamic characteristics were measured and verified at additional experimental points. The maximum errors yielded by the model, in terms of the resonant frequency and dynamic stiffness, were 1.6% and 7.1%, respectively.

In this study, the characteristics of the SKD61 material used for the stem of an extruder were analyzed through structural analysis, tensile testing, and fatigue testing. The extruder works by pushing a cylindrical billet into a die with a stem to reduce its cross-sectional area and increase its length, and it is currently used to extrude complex and diverse shapes of products in the field of plastic deformation processes. Finite element analysis was used to determine the maximum stress on the stem, which was found to be 1152 MPa, lower than the yield strength of 1325 MPa obtained from tensile testing. Fatigue testing was conducted using the stress–life (S–N) method, considering the characteristics of the stem, and statistical fatigue testing was employed to create an S–N curve. The predicted minimum fatigue life of the stem at room temperature was 424,998 cycles at the location with the highest stress, and the fatigue life decreased with increasing temperature. Overall, this study provides useful information for predicting the fatigue life of extruder stems and improving their durability.

Purpose: This study is to evaluate the location of descending palatine artery, the anatomy of pterygomaxillary junction, and the association between the obtained anatomic values and several variables. Methods: We studied 40 patients who were treated for dentofacial deformites from January 2010 to December 2012 in Ulsan University Hospital, Ulsan, Korea. Cone beam computed tomogram (CBCT) was done for all patients. The reference point was approximately 5 to 7 mm above anterior nasal spine on axial image. We evaluated the location of the greater palatine canal (line a: on the coronal view, the shortest line between the center of greater palatine canal and pterygoid fossa; distance a: the distance of line a). We also measured the thickness (line b: on the coronal view, the shortest line between maxillary posterior sinus wall and pterygoid fossa; distance b: distance of line b), width (line c: on the coronal view, the line perpendicular to the line b and the nearest line from the most concave point of lateral pterygoid plate to the medial pterygoid plate; distance c: distance of line c) and height (line d: on sagittal view, the vertically longest line of pterygoid junction; distance d: the distance of line d) in pterygomaxillary junctions. We evaluated the association between the obtained anatomic values and several variables (sex, age, height and weight). Results: The mean distance a was 4.78 mm, mean distance b was 5.53 mm, mean distance c was 8.01 mm and mean distance d was 13.22 mm. The differences between age and mean distance c and weight and mean distance d in pterygomaxillary junctions are statistically significant. Conclusion: There apparently is anatomic variation of pterygomaxillary junctions by various values, particularly weight and age in a Korean clinical population.

Health care marketers face unique challenges around the world, due in part to the role the health care field plays in contributing to public welfare. Hospital marketing in Korea is particularly challenging since Korean law prohibits hospitals from running any advertising. As a result, Korean hospitals depend heavily on customer relationship management (CRM). This study identifies five factors that influence the creation of brand equity through successful customer relationships: trust, customer satisfaction, relationship commitment, brand loyalty, and brand awareness. An empirical test of the relationships among these factors suggests that hospitals can be successful in creating image and positive brand equity if they can manage their customer relationships well.

요약 본 연구의 목적은 인터넷뱅킹과 지점뱅킹을 동시에 사용하고 있는 고객들을 대상으로 하여 그들의 인터넷채널에 대한 충성도를 향상시키는데 있어 중요한 변수인 신뢰와 관계결속과 그것의 영향변수 인 공유가치, 커뮤니케이션, 기회주의와의 관계를 온라인과 오프라인 채널올 통하여 동시에 고찰하고, 온라인과 오프라인 채널에 대한 신뢰의 상호작용과 그 역할을 고찰하는 것이다. 번수들간의 인과관계를 검정하기 위하여 LISREL 분석을 실시한 결과 다음과 같은 결론을 얻을 수 있었다. 첫째, 온라인 환경에서는 공유가치, 커뮤니케이션, 기회주의 모두 관계걸속에 중요한 영향번수로 나 타났다 둘째, 온라인 채널과 오프라인 채널에 대한 신뢰는 서로 밀접한 관계가 있는 것으로 나타났 다- 셋째, 온라인 채널에 대한 고객 충성도에 온라인 채널에 대한 신뢰뿐만 아니라 오프라인 채널에 대한 신뢰도 영흥을 미치는 것으로 나타났다.

본 연구의 목적은 IR 활동과 주주에 대한 관계마케팅간의 관련성을 연구하는 것이다. 본연구에 사용된 연구모형은 IR과 관계마케팅의 관련분야의 과거연구와 다양한 전문가들과의인터뷰를 통하여 축적된 자료들을 토대로 하여 구축되었다. 이러한 연구모형은 또한 과거연구와 전문가들과의 인터뷰를 통하여 얻어진 연구가셜들을 기반으로 하였다. LISREL 분석기법을 이용하여 자료분석이 시도되었다. 자료분석 결과에 의하면 IR활동들이 투자자의 신뢰와 관계결속에 결정적인 영향을 미치는 것으로 나타났다. 그리고 투자자의신뢰와 관계결속이 회사의 성과에 긍정적인 영향을 미치는 것으로 발견되었다. 따라서 IR활동들은 회사의 관계마케팅과 성과에 긍정적인 영향을 미친다는 결론을 도출하였다. 이러한결론을 바탕으로 IR활동과 관계마케팅의 관련성을 경영에 응용할 수 있는 다양한 마케팅전략이 제시되었다.

In Internet age, traditional transaction concepts are being examined in new perspectives. Electronic commerce, as a new transaction paradigm, is being paid attention to reexamine traditional marketing theories. In this study, equity is adapted to electronic commerce. We add Navigational Equity to existing equity concept: Payment and Service (Huppertz et a1 1978). The research model of this study consisted of three major constructs such as equity， normative comparison of equity and consumer satisfaction in electronic commerce. Additionally, the environments of Internet navigation, which include system quality, easy for use, social pressure, playful aspects, and security check, etc. were analyzed. The propositions were drawn from the research model of this study. These propositions will be used to generate hypotheses constructing simultaneous equation model. More empirical study of future is expected.

Comparison of the inferred amino acid sequence of orf AF1736 of Archaeoglobus fulgidus to that of Pseudomonas mevalonii HMG-CoA reductase suggested that AF1736 might encode a Class II HMG-CoA reductase. Following polymerase chain reaction-based cloning of AF1736 from A. fulgidus genomic DNA and expression in Escherichia coli, the encoded enzyme was purified to apparent homogeneity and its enzymic properties were determined. Activity was optimal at 85 degrees C, deltaHa was 54 kJ/mol, and the statin drug mevinolin inhibited competitively with HMG-CoA (Ki 180 microM). Protonated forms of His390 and Lys277, the apparent cognates of the active site histidine and lysine of the P. mevalonii enzyme, appear essential for activity. The mechanism proposed for catalysis of P. mevalonii HMG-CoA reductase thus appears valid for A. fulgidus HMG-CoA reductase. Unlike any other HMG-CoA reductase, the A. fulgidus enzyme exhibits dual coenzyme specificity. pH-activity profiles for all four reactions revealed that optimal activity using NADP(H) occurred at a pH from 1 to 3 units more acidic than that observed using NAD(H). Kinetic parameters were therefore determined for all substrates for all four catalyzed reactions using either NAD(H) or NADP(H). NADPH and NADH compete for occupancy of a common site. k(cat)[NAD(H)]/k(cat)[NADP(H)] varied from unity to under 70 for the four reactions, indicative of slight preference for NAD(H). The results indicate the importance of the protonated status of active site residues His390 and Lys277, shown by altered K(M) and k(cat) values, and indicate that NAD(H) and NADP(H) have comparable affinity for the same site.

The thermostable class I HMG-CoA reductase of Sulfolobus solfataricus offers potential for industrial applications and for the initiation of crystallization trials of a biosynthetic HMG-CoA reductase. However, of the 15 arginine codons of the hmgA gene that encodes S. solfataricus HMG-CoA reductase, 14 (93%) are AGA or AGG, the arginine codons used least frequently by Escherichia coli. The presence of these rare codons in tandem or in the first 20 codons of a gene can complicate expression of that gene in E. coli. Problems include premature chain termination and misincorporation of lysine for arginine. We therefore sought to improve the expression and subsequent yield of S. solfataricus HMG-CoA reductase by expanding the pool size of tRNA AGA,AGG , the tRNA that recognizes these two rare codons. Coexpression of the S. solfataricus hmgA gene with the argU gene that encodes tRNA AGA,AGG resulted in an over 10-fold increase in enzyme yield. This has provided significantly greater quantities of purified enzyme for potential industrial applications and for crystallographic characterization of a stable class I HMG-CoA reductase. It has, in addition, facilitated determination of kinetic parameters and of pH optima for all four catalyzed reactions, for determination of the K i for inhibition by the statin drug mevinolin, and for comparison of the properties of the HMG-CoA reductase of this thermophilic archaeon to those of other class I HMG-CoA reductases.

Sequence comparisons have implied the presence of genes encoding enzymes of the mevalonate pathway for isopentenyl diphosphate biosynthesis in the gram-positive pathogen Staphylococcus aureus . In this study we showed through genetic disruption experiments that mvaA , which encodes a putative class II 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase, is essential for in vitro growth of S. aureus . Supplementation of media with mevalonate permitted isolation of an auxotrophic mvaA null mutant that was attenuated for virulence in a murine hematogenous pyelonephritis infection model. The mvaA gene was cloned from S. aureus DNA and expressed with an N-terminal His tag in Escherichia coli . The encoded protein was affinity purified to apparent homogeneity and was shown to be a class II HMG-CoA reductase, the first class II eubacterial biosynthetic enzyme isolated. Unlike most other HMG-CoA reductases, the S. aureus enzyme exhibits dual coenzyme specificity for NADP(H) and NAD(H), but NADP(H) was the preferred coenzyme. Kinetic parameters were determined for all substrates for all four catalyzed reactions using either NADP(H) or NAD(H). In all instances optimal activity using NAD(H) occurred at a pH one to two units more acidic than that using NADP(H). pH profiles suggested that His378 and Lys263, the apparent cognates of the active-site histidine and lysine of Pseudomonas mevalonii HMG-CoA reductase, function in catalysis and that the general catalytic mechanism is valid for the S. aureus enzyme. Fluvastatin inhibited competitively with HMG-CoA, with a K i of 320 μM, over 10 4 higher than that for a class I HMG-CoA reductase. Bacterial class II HMG-CoA reductases thus are potential targets for antibacterial agents directed against multidrug-resistant gram-positive cocci.

There are two classes of 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase: the class I enzymes of eukaryotes and some archaea, and the class II enzymes of certain eubacteria. The activity of the class I Syrian hamster HMG-CoA reductase is regulated by phosphorylation-dephosphorylation of Ser871. Phosphorylation apparently prevents the active site histidine, His865, from protonating the inhibitory coenzyme A thioanion prior to its release from the enzyme. Structural evidence for this hypothesis is, however, lacking. The HMG-CoA reductase of the thermophilic archaeon Sulfolobus solfataricus, whose stability recommends it for physical studies, lacks both a phosphoacceptor serine and a protein kinase recognition motif. Consequently, its activity is not regulated by phosphorylation. We therefore employed site-directed mutagenesis to engineer an appropriately located phosphoacceptor serine and cAMP-dependent protein kinase recognition motif. Substitution of serine for Ala406, the apparent cognate of hamster Ser871, and replacement of Leu403 and Gly404 by arginine created S. solfataricus mutant enzyme L403R/G404R/A406S. The general properties of enzyme L403R/G404R/A406S (K(m) values, V(max), optimal pH and temperature) were essentially those of the wild-type enzyme. Exposure of enzyme L403R/G404R/A406S to [gamma-(32)P]ATP and cAMP-dependent protein kinase was accompanied by incorporation of (32)P(i) and by a parallel decrease in catalytic activity. Subsequent treatment with a protein phosphatase released enzyme-bound (32)P(i) and restored activity to pretreatment levels. The regulatory properties of enzyme L403R/G404R/A406S thus match those of the hamster enzyme. Solution of the three-dimensional structures of the phospho and dephospho forms of this mutant enzyme thus should reveal structural features critical for regulation of the activity of a class I HMG-CoA reductase.