• The Transactions of the Korean Institute of Power Electronics
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• v.12 no.6
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• pp.510-516
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• 2007

The proposed method offers an improved control method for high power density AC/DC adapter by using more energy efficient electrical equipments. Power factor correction (PFC) topology is based on boost topology with boundary conduction mode (BCM). DC/DC topology is based on half-bridge topology with fixed 50% duty and newly introduced off-time control method, which helps to reduce size of the semiconductor and the magnetic devices. Test results with 85W AC/DC adapter (18.5V/4.6A) design show that the measured efficiency is 90% with power density of $36W/in^3$. It also shows low no load power consumption of about 0.5W.

• Journal of Advanced Marine Engineering and Technology
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• v.23 no.4
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• pp.453-461
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• 1999

The estimation of fatigue life at the design stage is very important in order to arrive at feasible and cost effective solutions considering the total lifetime of the structure and machinery compo-nents. In this study the practical procedure of prediction of fatigue life by use of cumulative damage factors based on Miner-Palmgren hypothesis and probability density function is shown with a $135,000m^3$ LNG tank being used as an example. In particular the parameters of Weibull distribution taht determine the stress spectrum are dis-cussed. At the end some of uncertainties associated with fatigue life prediction are discussed. The main results obtained from this study are as follows: 1. The practical procedure of prediction of fatigue life by use of cumulative damage factors expressed in combination of probability density function and S-N data is proposed. 2. The calculated fatigue life is influenced by the shape parameter and stress block. The conser-vative fatigue design can be achieved when using higher value of shape parameter and the stress blocks divded into more stress blocks.

• The Transactions of the Korean Institute of Power Electronics
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• v.15 no.4
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• pp.259-265
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• 2010

The proposed method offers an improved control method for high power density AC/DC adapter by using more energy efficient electrical equipments. Power factor corrector (PFC) topology is based on boost topology with boundary conduction mode (BCM) and DC/DC topology is based on LLC resonant converter, which helps to reduce size of the semiconductor and the magnetic devices. Test results with 85W AC/DC adapter (18.5V/4.6A) design shows that the measured efficiency is 90% at $90V_{rms}$ input voltage with power density of $36W/in^3$. It also shows low no load power consumption of about 0.5W.

• Journal of The Korean Astronomical Society
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• v.17 no.2
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• pp.115-125
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• 1984

Effect of magnetic field on the thermal instability is studied in the radiatively cooling region behind an interstellar shock of moderate propagation velocity (${\sim}10\;km/sec$). It is shown that the presence of interstellar magnetic field of a few micro gauss is very effective in preventing the thermal instability from building-up density concentration. In the absence of magnetic field, the shock-induced thermal instability amplifies preshock density inhomogeneity by more than an order of magnitude. However, in the presence of magnetic field, the amplified density contrast is shown to be only a factor 2.

• JSTS:Journal of Semiconductor Technology and Science
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• v.1 no.3
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• pp.189-192
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• 2001

A simple metal-insulator-metal (MIM) capacitor in a standard $0.25{\;}\mu\textrm{m}$ digital CMOS process is described. Using all six interconnect layers, this capacitor exploits both the lateral and vertical electrical fields to increase the capacitance density (capacitance per unit area). Compared to a conventional parallel plate capacitor in the four upper metal layers, this capacitor achieves lower parasitic substrate capacitance, and improves the capacitance density by a factor of 4. Measurements and an extracted model for the capacitor are also presented. Calculations, model and measurements agree very well.

• Journal of The Korean Astronomical Society
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• v.13 no.1
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• pp.27-33
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• 1980

Surface density distributions for globular clusters were obtained from photoelectric surface photometry (using centered aperture photometry). These surface brightness profiles were then compared with the theoretical surface density distribution of King's model. From the comparison of the theoretical and observed surface density distributions, we determine he structural parameters of the clusters (the core radius $r_c$, the tidal cut off $r_t$, and the concentration factor C).

• Proceedings of the Korean Society Of Semiconductor Equipment Technology
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• 2006.05a
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• pp.21-40
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• 2006

[ ${\Box}$ ] Opportunities for PRAM Nearly ideal memory characteristics Potential for high density & low cost memory ${\Box}$ Technical Challenges Writing current reduction is the most urgent issue. ${\to}$ chalcogenide, programming volume, current density, heat loss control Improvement of writing speed, reliability ${\Box}$ Prospects (PRAM as a Mainstream Memory) Evenn, We have demonstrated 256Mb PRAM Realization of high density and low cost PRAM with good reliability will be key succss factor. We need to develop PRAM specific applications.

• Communications for Statistical Applications and Methods
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• v.7 no.1
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• pp.141-150
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• 2000

In this paper we propose a method of computing Bayes factor to detect an outlier in a random effects model. When no information is available and hence improper noninformative priors should be used Bayes factor includes the unspecified constants and has complicated computational burden. To solve this problem we use the fractional Bayes factor (FBF) of O-Hagan(1995) and the generalized Savage0-Dickey density ratio of Verdinelli and Wasserman (1995) The proposed method is applied to outlier deterction problem We perform a simulation of the proposed approach with a simulated data set including an outlier and also analyze a real data set.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.25 no.7
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• pp.1155-1162
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• 2001

Sihs minimum strain energy density criterion(SED) often used in the mixed mode problem has the ambiguity of the choice of minimum values. In this paper, as the method to solve the problem of SED, maximum minimum strain energy density criterion is proposed that the crack propagates in the direction of having the maximum among the minimum values of modified strain energy density factor(MS), i.e., sign($\sigma$(sub)$\theta$).Smin.

• Journal of the Korean Home Economics Association
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• v.29 no.3
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• pp.61-69
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• 1991

The relationships between nutrients intake, physical activity and bone mineral density were investigated in 19 elderly men aged 71-80 years. A trained nutritionist interviewed usual dietary intake and daily activity with a questionnaire, and bone mineral density was measured at the lumbar spine and three regions of the proximal femur (femur neck, Ward's triangle and trochanter) with a Luna DP3 dual photon absorptiometry. The correlations between dietary calcium intake and bone mineral density at the lumbar spine and trochanteric region were significant at P<0.05 and P<0.01 level respectively. the significant correlations were also found between vitamin A(P<0.005), riboflavin(P<0.01), and ascorbic acid(P<0.05) intake and bone mineral density at these sites. Higher physical activity was associated with greater bone mineral density of four sites, but this was not significant. But there were significant relationships between total energy expenditure and bone mineral density of the lumbar spine(P<0.01), femur neck (P<0.05) and Ward's triangle(P<0.05). In this study the results revealed that bone mineral density of the lumbar spine and trochanteric region were associated with dietary calcium intake. And bone mineral density of the femur neck and Ward's triangle were related to physical activity but not to nutrients intake. In conclusion, dietary calcium intake seems to be a important factor for greater bone mineral density. Further evidence will be needed that physical activity protects against bone fracture and osteoporosis in the edlerly.