• Bulletin of the Korean Chemical Society
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• v.28 no.5
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• pp.745-750
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• 2007

An isotope dilution-liquid chromatography/tandem mass spectrometric method was developed as a candidate reference method for the accurate determination of folic acid in infant milk formula. Sample was spiked with 13C5-folic acid and then extracted with phosphate buffer (pH 6) solution. The extract was further cleaned up by deproteinization followed by a C18 solid-phase extraction cartridge. The extract was analyzed by using LC/ ESI/MS/MS with selectively monitoring the collisionally induced dissociation channels of m/z 442 → m/z 295 and m/z 447 → m/z 295, which are the neutral glutamyl loss from the [M+H]+ ions of folic acid and 13C5-folic acid, respectively. LC/MS/MS chromatograms showed substantially reduced background from chemical noises compared to LC/MS chromatograms. Repeatability and reproducibility studies showed that the LC/MS/ MS method is a reliable and reproducible method which can provide less than 1.5 relative percentage of method precision.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.12 no.7
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• pp.1076-1085
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• 2001

In this paper, the FMM(Fast Multipole Method) combined with GMRES(Generalized Minimal RESidual Method) matrix solver is used to extract the parasitic impedance for complicated 3-D structures in uniform dielectric materials which limit the use of MoM(Method of Moment) due to its large computation time and memory requirement. This algorithm is a fast multipole-accelerated method based on quasistatic analysis and is very efficient for computing impedance between conductors. This paper proved the accuracy and efficiency of the FMM by comparing with MoM in simple examples. Finally the parasitic impedance of FC-PGA(Flip Chip Pin Grid Array) Package pins has been extracted by this algorithm and we have considered the possibility of the EMI/EMC problem caused by the signal interference.

• Journal of Forest and Environmental Science
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• v.27 no.3
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• pp.195-203
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• 2011

Forest in the our country is in the age that needs positive operation in order to foster economical forest. Multiple operations for making valuable forest should be conducted steadily and timely from afforestation to harvesting. In order to execute these kinds of forest operations, the construction of skid trail network that can be effectively used as a pathway for forestry machine and working space is necessary. To investigate facility effect of skid trail network, we executed the location of skid trail network through centroid method by GIS for 50ha of harvesting workplace in mechanized model forest located in Hongcheon, Gangwon Province. As a result of this research, skid trail density in this area changed from 79m/ha with current method to 42m/ha with improved method. It appeared that skid trail density with improved method is nearly half of current method even though the cutting area is the same as the current cutting area. Also, skidding distance changed from 117m with current method to 57m with improved method. It appears that skidding distance with improved method is nearly half of current method even though cutting area was enlarged in adjacent tending cutting area.

• Economic and Environmental Geology
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• v.44 no.5
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• pp.387-397
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• 2011

In this study, we conducted the study of the merits and demerits of the laser flash and the divided-bar methods for measuring the thermal conductivity of rocks and investigated applicability of the divided-bar apparatus which was developed by KIGAM. The laser flash method can measure thermal diffusivity, specific heat capacity, and thermal conductivity of rocks with even small thickness (< ~3 mm) in the high temperature range($25-200^{\circ}C$) in non-contact mode. For the laser flash method, samples must be uniform and homogeneous. In the case of the divided-bar method, the apparatus measures only thermal conductivity of rock samples at the room temperature. We measured thermal conductivities of 12 rock samples with low density and high porosity using two methods. In the laser flash method, there exist potential errors caused by the effect of pulse dispersion and reflection by various minerals and porosity in rock samples; the difference in thermal conductivity values measured on the front surface and the opposite surface ranges from 0.001 to 0.140 W/mK with the standard deviation of 0.003~0.089 W/mK, which seems to be caused by heterogeneity of rock samples. On the contrary, the divided-bar apparatus shows stable thermal conductivity measurements and relatively small measurement errors; the difference in thermal conductivity values, just as we applied to the laser frash method, is 0.001~0.016 W/mK with the standard deviation 0.001~0.034 W/mK. In turn, the divided-bar method can be applied to more thick samples that are more representative of bulk thermal conductivity.

• KSBB Journal
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• v.21 no.5
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• pp.371-375
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• 2006

Frontal analysis(FA) and Pulsed input method(PIM) have been frequently utilized to measure isotherm of single solute, as well as non-competitive isotherms of two solutes in chromatography(1). FA and PIM were used in this study as complementary methods to measure adsorption isotherms of loxoprofen racemate in HPLC. Prior to FA and PIM experiments, measurements of loxoprofen solubility were made at hexane/ethanol=50/50, 80/20, 95/5(v/v) with acetic acid(0.5%) for adjusting pH. The last composition(95/5) of hexane/ethanol allows us to separate loxoprofen racemate into two forms(retentate, extract). PIM and FA were used to determine the isotherms of re-and ex-loxoprofen.

• Journal of odor and indoor environment
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• v.17 no.4
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• pp.362-371
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• 2018

Indoor Volatile organic compounds (VOCs) are classified as known or possible toxicants and odorants. This study characterized VOC levels in 11 homes in an area in the capital of Seoul by using two different methods of VOCs sampling, which are the active sampling using a thermal sorption tube and the passive sampling using a diffusion sampler. When using the active sampling method, the total target VOC concentration ranged from 41.7 to $420.7{\mu}g/m^3$ (mean $230.4{\mu}g/m^3$ ; median $221.8{\mu}g/m^3$) during winter and 21.3 to $1,431.9{\mu}g/m^3$ (mean $340.1{\mu}g/m^3$; median $175.4{\mu}g/m^3$) during summer. When using the passive method, 29.6 to $257.5{\mu}g/m^3$ (mean $81.8{\mu}g/m^3$; median $49.4{\mu}g/m^3$) during winter and 1.2 to $5,131.1{\mu}g/m^3$ (mean $1,758.8{\mu}g/m^3$; median $1,375.1{\mu}g/m^3$) during summer. Forty-nine VOCs were quantified and toluene showed the highest concentration regardless of the season and the sampling method studied. The distribution of VOCs was relatively varied by using the active method. However, it showed a low correlation with indoor environmental factors such as room temperature, humidity and ventilation time. The correlation between indoor environmental factors and VOCs were relatively high in the passive method. In particular, these characteristics were confirmed by principal component analysis.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.20 no.8
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• pp.791-796
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• 2009

A hybrid iterative physical optics-method of moments(IPO-MoM) technique is presented for the analysis of jet engine structures which are both electrically large and complex. In this technique, the IPO method is used to analyze smooth inlet region and the MoM method is used to analyze electrically complex region inclusive of blades and hub. It is efficient and accurate by virtue of combining the respective merits of both methods. Numerical results are presented and validated through comparison with Mode-FDTD and measured results.

• Magazine of the Korean Society of Agricultural Engineers
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• v.33 no.4
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• pp.105-120
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• 1991

This study was performed to investigate the minimum safety factor of embankment in consideration of seismic coefficient by the psuedo-static analysis The variables were cohesion, the internal friction angle, angle of slope, height of seepage, height of embankment, depth of replacement The results obtained were compared with those by Fellenius method, simplified Bishop method and Janbu method. The results were summarized as follows: 1.The increasing rate of the minimum safety factor with the increasing of cohesion appeared larger in Fellenius method and Bishop method than in Janbu method. And that with the increasing of the internal friction angle appeared the lowest value in Janbu method. The minimum safety factor was influenced larger on the internal friction angle than on cohesion. 2.The variation of the minimum safety factor with the height of seepage at 0m and 5 m was nearly similar to Fellenius method, Bishop method and Janbu method. On the other hand, it was decreased suddenly at 25 m. 3.The minimum safety factor with the height of embankment was decreased remarkably under 10 m with the increasing of seismic coefficient. But, it was decreased slowly more than 10 m. As the height of embankment was low, the influence of cohesion appeared larger. 4.In heigher case of the depth of replacement, the phenomenon of reduction of the minimum safety factor appeared remarkably with seismic coefficient increased. And in lower case of the depth of replacement, the minimum safety factor was similar in Fellenius method and Bishop mehtod. But it appeared larger in Bishop method and Janbu method than in Fellenius method with the depth of replacement increased. 5.As the cohesion and the internal friction angle were large, the phenomenon of reduction of the minimum safety factor with the increasing of seismic coefficient appeared remarkably. Also, the influence of seismic coefficient in minimum safety factor appeared larger with the soil parameter increased. 6.When the seismic coefficient was considerated, investigation of the structural body on the slope stability appeared profitably in Fellenius method and Janbu method than in Bishop method.

• The KIPS Transactions:PartC
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• v.18C no.1
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• pp.1-6
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• 2011

The performance and practicality of cryptosystem for encryption, decryption, and primality test is primarily determined by the implementation efficiency of the modular exponentiation of $a^b$(mod n). To compute $a^b$(mod n), the standard binary squaring still seems to be the best choice. But, the d-ary, (d=2,3,4,5,6) method is more efficient in large b bits. This paper suggests m-numeral system modular exponentiation. This method can be apply to$b{\equiv}0$(mod m), $2{\leq}m{\leq}16$. And, also suggests the another method that is exit the algorithm in the case of the result is 1 or a.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.13 no.3
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• pp.35-43
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• 2003

The randomization of scalar multiplication in ECC is one of the fundamental concepts in defense methods against side-channel attacks. This paper proposes a countermeasure against simple and differential power analysis attacks through randomizing the transformed m-ary method based on a random m-ary receding algorithm. The proposed method requires an additional computational load compared to the standard m-ary method, yet the power consumption is independent of the secret key. Accordingly, since computational tracks using random window width can resist against SPA and DPA, the proposed countermeasure can improve the security for smart cards.