• Ocean and Polar Research
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• v.38 no.4
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• pp.295-301
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• 2016

The nomenclature of the sea nettle jellyfish from Korea was initially described as Dactylometra quinquecirrha Agassiz, 1862. However its identity has been questioned on the basis of its local distribution and molecular data. Here, we examined morphology and DNA sequences of nuclear rDNA using specimens collected from southern Korean waters in August 2014. Based on morphological characteristics (bell size, umbrella pattern, number of tentacles and lappets) and distribution locality, we reassign the Korean D. quinquecirrha to Chrysaora pacifica (Goette, 1886), and provide a re-description accordingly. The molecular identity of C. pacifica was further confirmed by comparison of nuclear ribosomal DNA sequences.

• Journal of the Korean Applied Science and Technology
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• v.9 no.1
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• pp.7-13
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• 1992

Lipases catalyzed the transesterification reaction between esters and various primary and secondary alcohols in a 99% organic medium, porcine pancreatic, yeast, mold lipases can vigorously act as catalysts in a number of nearly anhydrous organic solvents. Various transesterification reactions catalyzed by porcine pancreatic lipase in hexane obey Michaelis-Menten kinetics. The dependence of the catalytic activity of the enzyme in organic media on the pH of the aqueous solution from which it was recovered is bell-shaped, with the maximum coinciding with the pH optimum of the enzymatic activity in water. The catalytic power exhibited by the lipases in organic solvents is comparable to that displayed in water. In addition to transesterification, lipases Can catalyze several other processes in organic media.

• International Journal of Fluid Machinery and Systems
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• v.3 no.1
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• pp.39-49
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• 2010

In this paper, a numerical study has been carried out to investigate the influence of jet fan design variables on the performance of a jet fan. In order to achieve an optimum jet fan design and to explain the interactions between the different geometric configurations in the jet fan, three-dimensional computational fluid dynamics and the DOE method have been applied. Several geometric variables, i.e., hub-tip ratio, meridional shape, rotor stagger angle, number of rotor-stator blades and stator geometry, were employed to improve the performance of the jet fan. The objective functions are defined as the exit velocity and total efficiency at the operating condition. Based on the results of computational analyses, the performance of the jet fan was significantly improved. The performance degradations when the jet fan is operated in the reverse direction are also discussed.

• Economic and Environmental Geology
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• v.32 no.6
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• pp.653-660
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• 1999

Any mechanical system has a natural oscillation which can be excited, and the earth is no exception. The earth can oscillate in an indefinite number of normal modes of oscillation, rather like a giant bell. The various free modes are generally sparated into two categoridal modes and toroidal modes. Clearly the toroidal modes will produce no perturvation of the gravity field and no vertical acceleration on the surface of the earth. Hence only spheroidal modes can be detected with a gravimeter. EarthTide gravimeter was installed at AIMST in order to observe free modes of the earth. Eight major earthquakes including chinese earthquake (magnitude 7.3) with free oscillations of the earth are observed during one year (1998. 8. 1∼1999.7.31). And then the earth tides components were eilminated from earthquake records using a numerical Butterworth highpass filter. Spectral analysis of gravity readings repersent that 48 observations of shheroidal modes. The relationships between instrumental observations and theoretical predictions based on the Gutenberg earth model agree well those resulting from free oscillation in Korea.

• Advances in concrete construction
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• v.14 no.1
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• pp.35-43
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• 2022

Based on novel Galerkin's technique, the theoretical study gives a prediction to estimate the vibrations of FG rotating cylindrical shell. Terms of ring supports have been introduced by a polynomial function. Three different laws of volume fraction are utilized for the vibration of cylindrical shells. Variation frequencies with the locations of ring supports have been analyzed and these ring supports are placed round the circumferential direction. The base of this approach is an approximate estimation of eigenvalues of proper functions which are the results of solutions of vibrating equation. Each longitudinal wave number corresponds to a particular boundary condition. The results are given in tabular and graphical forms. By increasing different value of height-to-radius ratio, the resulting backward and forward frequencies increase and frequencies decrease on increasing length-to-radius ratio. There is a new form of frequencies is obtained for different positions of ring supports, which is bell shaped. Moreover, on increasing the rotating speed, the backward frequencies increases and forward frequencies decreases.

• East Asian mathematical journal
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• v.39 no.5
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• pp.523-528
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• 2023

Let S_n = [S(i, j)]_1≤i,j≤n and S^*_n = [S(i + j, j)]_1≤i,j≤n where S(i, j) is the Stirling number of the second kind. Choi and Jo [On the determinants of the square-type Stirling matrix and Bell matrix, Int. J. Math. Math. Sci. 2021] obtained the diagonal entries of matrix U in the LU-factorization of S^*_n for calculating the determinant of S^*_n, where L = S_n. In this paper, we compute the all entries of U in the LU-factorization of matrix S^*_n. This implies the identities related to Stirling numbers of both kinds.

• Nuclear Engineering and Technology
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• v.55 no.3
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• pp.1181-1190
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• 2023

Hydraulic performance and flow resistance tests were performed to confirm the main parameters of the hydraulic instrumentation that can affect the pump performance of the reactor coolant pump. The flow resistance test offers important experimental data, which are necessary to predict the behavior of the primary coolant when the circulation of the reactor coolant pump is stopped. Moreover, the shape of the hydraulic section of the pump, which was considered in the test, was prepared to compare the mixed-flow- and axial-flow-type models, the difference in the number of blades of the impeller and diffuser, the difference in the shape of the impeller blade and its thickness, and the effect of coating at the suction bell. Additionally, five models of the hydraulic part were manufactured for the experiments. In this study, the differences in performance owing to the design factors were confirmed through the experimental results.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.8 no.3
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• pp.762-777
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• 2014

With the increasing usage of cloud applications such as MapReduce and social networking, the amount of data traffic in data center networks continues to grow. Moreover, these appli-cations follow the incast traffic pattern, where a large burst of traffic sent by a number of senders, accumulates simultaneously at the shallow-buffered data center switches. This causes severe packet losses. The currently deployed TCP is custom-tailored for the wide-area Internet. This causes cloud applications to suffer long completion times towing to the packet losses, and hence, results in a poor quality of service. An Explicit Congestion Notification (ECN)-based approach is an attractive solution that conservatively adjusts to the network congestion in advance. This legacy approach, however, lacks scalability in terms of the number of flows. In this paper, we reveal the primary cause of the scalability issue through analysis, and propose a new congestion-control algorithm called FaST. FaST employs a novel, virtual congestion window to conduct fine-grained congestion control that results in improved scalability. Fur-thermore, FaST is easy to deploy since it requires only a few software modifications at the server-side. Through ns-3 simulations, we show that FaST improves the scalability of data center networks compared with the existing approaches.

• Journal of Korean Academy of Nursing
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• v.12 no.2
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• pp.91-104
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• 1982

This study on stressful life events and coping methods of medical patients and community people was applied to people who was divided into two groups from July 19 to Aug. 7, 1982, One is hospitalized patients in medical wards of two university hospitals in Seoul. The other is inhibitants in eight Dongs of Seoul. This study compared the number and seversity of stressful life events reported by medical patients and community people within last six months, identified coping methods used by the two groups and explored the relationship between stressful life events and coping methods. Two instruments are used in this study. The first one to measure stressful life events, is Holmes ＆ Rahe(1967)'s S.R.R.S.(Soual Readjustment Rating Scale), which is translated ＆ amended, So that it consists of 51 items. The second one is for evaluating coping method. It consists of 36 items amended through preliminary test after consideration of related literature review and survey on the basis of Bell(1877)’s‘18-item-Questionnaire.’The materials were analyzed by S.P.S.S. (Statistical Package for the Social Science) program. The results of analysis were as follows: 1. There were no significant difference in the number and severity of stressful life events reported by medical patients and community people (p>.05). 2. There were no significant difference in use of coping methods (p>.05). 3. Stressful life events showed a positive correlation with coping methods (r=.363).

• Journal of Korean Academy of Nursing
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• v.13 no.2
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• pp.58-69
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• 1983

This study on stressful life events and coping methods of hypertensive and nonhypertensive patients was applied to people who was divided into two groups from April 5 to March 10, 19 83. One is hospitalized patients in medical wards of three university hospital in Seoul. The other is inhibitants in two Dongs of Seoul. This study compared the number and seversity of stressful life events reported by hypertensive and nonhypertensive patients, indentified coping methods used by the two groups and explored the relationship between stressful life events and coping methods. Two instruments are used in this study. The first one to measure stressful life events, is Holmes ＆ Rahe (1967)'s S.R.R.S. (Social Readjustment Rating Scale). Which is translated & am-ended. So that it consists of 46 items. The second one is for evaluating coping method. It consists of f items amended through preliminary test after consideration of related literature review and survey on the basis of Bell (1977)'s‘18-item-Questionnaire.’The materials were analyzed by S.P.S.S. (Statistical Package for the Social Science) program-The results of analysis were as follows: 1. There were no significant difference in the number and severity of stressful life events reported by hypertensive and nonhypertensive patients (p>.05). 2. There were significant difference in use of short-term coping methods (p<.01) and long-term coping methods (p<.05).