• 소성∙가공
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• 제3권1호
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• pp.97-109
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• 1994

Closed-die forging of the spur gears with circular are fillet has been analyses by using the upper-bound method. A kinematically admissible velocity field has been developed, wherein, the tooth profile consists of the involute curve and the circular arc fillet. In the analysis, the deformation regions have been divided into eight zones. A constant frictional stress has been assumed on the contacting surfaces Utilizing the formulated velocity field, numerical calculations have been carried out to investigate the effects of various parameters, such as module, number of teeth, addendum modification coefficient and friction factor, on the relative forging pressure of spur gears. As the result of numerical calculations, the relative forging pressure does not change so much against the variation of module. On the other hand, the relative forging pressure increases at the final filling stage as the addendum modification coefficient increases.

• 한국작물학회지
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• 제43권2호
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• pp.89-94
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• 1998

Granule bound starch synthase (GBSS), also known as the '"waxy protein'", is responsible for the synthesis of amylose in the amyloplasts of cereal crops. In hexaploid wheat (Triticum aestivum L.), GBSS is involved in amylose synthesis and rolls as an important factor to determine flour quality and end-use quality in food products. Genes on three Wx loci have been found to encode GBSS in common wheats. We developed techniques for the purification and separation of GBSS in wheat. Three major GBSS isoforms, which were encoded by the genes on three loci, Wx-A1, Wx-B1, and Wx-D1 migrating differently by one dimensional SDS-po-lyacrylamide gel electrophoresis (1D SDS-PAGE), were identified. GBSS from 66 Korean hard and soft winter wheats were purified and determined for their Wx loci and four of them were identified possessing a null allele either at the Wx-A1 and Wx-B1 loci. With help of identification of three GBSS isoforms using 1D SDS-PAGE system, we are able to identify and monitor Wx gene expressions in breeding materials for developing waxy or partial waxy wheats without experiencing consecutive selecting generations.cting generations.

• 센서학회지
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• 제22권3호
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• pp.185-190
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• 2013

We report on direct finding of how the morphology (i.e. filopodia width) of $CD4^+$ T lymphocytes correlates with the size of the quartz nanohohole arrays (QNHAs, 140, 200, 270, and 550 nm in diameter) via scanning electron microscopy (SEM). This research exhibits that the filopodia of $CD4^+$ T-lymphocytes extended on the QNHA substrates were observed to increase in width by increasing the size of QNHA in diameter from 140 to 550 nm. This strong linear response ($R^2$=0.988, n = 6) in filopodia's width of surface-bound $CD4^+$ T-cells with topographical structures of QNHA can be explained by contact guidance between the cells and solid-state substrates. Furthermore, this research suggests that the protruded filopodia of surface-bound T-lymphocytes can be used as a biosensor for sensing the topographical information of the nano-patterned substrates.

• 한국지하수토양환경학회:학술대회논문집
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• 한국지하수토양환경학회 2004년도 총회 및 춘계학술발표회
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• pp.376-379
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• 2004

pH has been regarded as a master variable governing the heavy metal sorption on fly ash. However, the chemical constituents in the fly ash could also suggest a potential sorption site for heavy metals. So, in this study sequential extraction method is employed to evaluate the sorption behavior of fly ash for cadmium. Two different fly ashes (S-fly ash, T-fly ash) were obtained from different power plants in Korea. First, cadmium is adsorbed under four different initial pHs. And, Cd sorbed in fly ash was sequentially desorbed following the sequential extraction method suggested by Tessier. In test results, the effect of pH increase was differently exerted in two fly ash. In S-fly ash, exchangeable fraction was dominated in low initial pH, however, as increasing initial pH, the fraction bound to carbonate increased. In the T-fly ash, regardless of initial pH the fraction bound to carbonate was major part of sorption estimated. The fraction bound to Fe/Mn oxide was about 10% in T-fly ash, and 5% in S-fly ash at high pH.

• Elastomers and Composites
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• 제14권2호
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• pp.83-102
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• 1979

The purpose of this dissertation is to study some of the vulcanization characteristics of rubber-bound antioxidants such as G-1, [N-(3-methacryloyloxy-2-hydroxypropyl)-N'-phenyl-p-phenylene diamine] and acryl, acrylamide & acrylester substituted hindered phenols. The influence of these antioxidants upon vulcanization characteristics in NR and SBR compounds in the presence of vulcanizing accelerators such as MSA, TT, DM, M & D was evaluated by means of Oscillationg Disk Cure Meter. The comparison was also made between the influence of rubber-bound antioxidants and that of conventional non-reactive antioxidants such as N-alkyl substituted PADA series. Regarding the influence of reactive type antioxidant G-1 mixed with accelerator TT upon vulcanization characteristics, rapid onset of vulcanization and higher degree of cross-linking were discovered, whereas in the case of accelerator M and DM, the result was slow onset of vulcanization and lesser degree of cross-linking. The comparison of vulcanizing characteristics among acrylic substituted hindered phenols as antioxidants was made under several vulcanization accelerator systems. Under such systems, MSA-S combined accelerator caused the onset of vulcanization to slow down and lowered the degree of cross-linking. Finally in the case of hindered phenol derivatives containing longer substituent, the delayed onset of vulcanization and the lowered degree of cross-linking could be discerned.

• 한국환경농학회지
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• 제28권4호
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• pp.453-461
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• 2009

Killifish (Oryzias latipes) were exposed to an organophosphate pesticide, pirimiphos-methyl, in a flow-through system to determine the bioconcentration factor (BCF) following GLP (Good Laboratory Practice). This study was conducted at two different concentrations (1 and $10\;{\mu}$g/L) of $^{14}C$-labeled pirimiphos-methyl for 28 days uptake and 14 days depuration according to the OECD 305 test guideline. The $BCF_{ss}$ for total radioactive residues in whole fish were 1,251 and 1,277 for low and high concentrations, respectively. The $BCF_k$ based on the uptake and depuration rate constants were 1,200 for both low and high concentrations. During the depuration phase, the accumulated test substance was rapidly depurated from fish. Greater than 95% of the residue at steady-state was depurated after 2 days. Although the measured BCF values were high, pirimiphos-methyl could be evaluated as a low risk from bioaccumulation by aquatic organisms due to the short depuration period and low amount of bound residue (1.5%). We suggest that in evaluating bioaccumulation, not only the BCF should be considered, but also depuration time and bound residue in aquatic organisms give an indication of the potential environmental risks.

• 지역사회간호학회지
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• 제22권2호
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• pp.192-203
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• 2011

Purpose: This study was conducted to develop and assess the feasibility of an upper extremity exercise program based on Patterned Sensory Enhancement (PSE) for home-bound stroke patients by measuring the level of upper extremity function, depression, and interpersonal relationship. Methods: The experiments were performed on stroke patients at three different rehabilitation centers in Incheon City. Twenty patients participated in the experimental group or in the control group. The program was executed three times a week for 6 weeks. Data were collected from August to October, 2006. Manual Function Test was used to quantify and evaluate upper extremity function. The depression level and the effectiveness of interpersonal relationship were quantified and measured using CES-D and Relationship Change Scale, respectively. Results: The effectiveness of upper extremity function of stroke patients who participated in the PSE upper extremity exercise program was higher than that of non-participating patients. The depression level decreased and interpersonal relationship improved in the stroke patients who participated in this program compared to those who did not. Conclusion: These findings prove that the PSE upper extremity exercise program for home-bound stroke patients was an effective strategy for enhancing upper extremity function, decreasing the depression level, and improving interpersonal relationships.

• Ocean and Polar Research
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• 제33권1호
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• pp.77-83
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• 2011

In this study we examined the economic value of restoration technology for oil spill using contingent value methods. One and one half approach to questionnaires can be taken when analyzing tax payer situations as well as single bound approach. The results of the empirical analysis suggest three conclusions. First, the economic value of the restoration technology considered are estimated to be between 8,439 won to 11,867 won per month. Second, the WTP is estimated differently depending on the approaches, OOHB and SB, and the degrees of difference are very sensitive to the model specifications. This empirical result supports the argument for using interval for the economic value when using CVM. Third, the empirical results may provide useful input to policy authorities attempting to estimate the economic justification of the R&D investment for developing an ocean environmental restoration technology.

• 무역상무연구
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• 제32권
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• pp.3-27
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• 2006

The Pennzoil case and the SME case illustrate the difficulties which originate from inadequate drafting of letters of intent. In both cases the judges had to face the crucial question as to whether or not a given letter of intent had a binding nature; they had in other words to decide whether the wills expressed in such letters still belonged to the pre-contractual stage, or whether their incorporation into a pre-contractual document meant that negotiations were over and binding obligations had already arisen for the parties. In other words, some problems may occur when a party has documented a stage in the negotiations by letters of intent. The letters may well explicitly spell out if, and to what extent, the parties should be bound by what they have already agreed or to carry on negotiations in order to reach the final contract. But if the letters are silent, some problems would arise. Contracting parties are, therefore, well advised to spell out if, and to what extent, they should be bound by such preliminary agreements. Here again, it might be prudent to explicitly set forth that the parties should not be bound until there is a final written contract signed by authorized representatives of the parties but that they shall abstain from such measures which may defeat their stated objective to reach final agreement, e.g. by diminishing the value of performance under the contemplated contract.

• 대한산업공학회지
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• 제19권2호
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• pp.3-13
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• 1993

In this study, we develop a B & B type algorithm for the concave minimization problem with 0-1 knapsack constraint. Our algorithm reformulates the original problem into the singly linearly constrained concave minimization problem by relaxing 0-1 integer constraint in order to get a lower bound. But this relaxed problem is the concave minimization problem known as NP-hard. Thus the linear function that underestimates the concave objective function over the given domain set is introduced. The introduction of this function bears the following important meanings. Firstly, we can efficiently calculate the lower bound of the optimal object value using the conventional convex optimization methods. Secondly, the above linear function like the concave objective function generates the vertices of the relaxed solution set of the subproblem, which is used to update the upper bound. The fact that the linear underestimating function is uniquely determined over a given simplex enables us to fix underestimating function by considering the simplex containing the relaxed solution set. The initial containing simplex that is the intersection of the linear constraint and the nonnegative orthant is sequentially partitioned into the subsimplices which are related to subproblems.