• Journal of the Mineralogical Society of Korea
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• v.21 no.1
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• pp.27-35
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• 2008

Characterization of mineralogy and nanocrystals of ingredient materials of $Lumilite^{(R)}$ used for water treatment was made using optical microscopy, XRD, SEM, FTIR, and XRF analyses. Constituent minerals identified by XRD and microscope are clinoptilolite, illite, quartz, and albite, characterized by dense and fine texture. The cross section of nanocrystals with the size $70{$\sim}100\;nm$ is generally round or subround. Numerous spheroids with few nanometers in diameter are extensively formed on the surface of nanocrystals. Bulk chemistry is $SiO_2$ $74.22{\sim}75.65\;wt.%$, $Al_2O_3$ $13.25{\sim}13.72\;wt.%$, CaO $4.23{\sim}5.15\;wt.%$, with other major elements being minimal. When heated to $700^{\circ}C$, the crystal structure was mostly destroyed, though it persisted to $500^{\circ}C$. It is likely that high capacity and applications of $Lumilite^{(R)}$ for water treatment are originated from its structural properties such as development of nanocrystals and various tiny pores.

• Journal of the Korean Society for Marine Environment & Energy
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• v.12 no.1
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• pp.15-22
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• 2009

Auto-navigation algorithm have been studied to avoid collision and grounding of a ship due to human error. There have been many research on collision avoidance algorithms but they have been validated little on the real coastal traffic situation. In this study, a Collision Avoidance algorithm is developed by using Fuzzy algorithm and the concept of Changeable Action Space Searching (CAS). In the first step, on a basis of collision risk calculated from fuzzy algorithm in the current time(t=to), alternative Action Space for collision avoidance is planned. In the second step, next alternative Action Space for collision avoidance in the future($t=to+{\Delta}t$) is corrected and re-planned with re-evaluated collision risk. In the third step, the safest and most effective course among Action Space is selected by using optimization method in real time. In this paper, the main features of the developed collision avoidance algorithm (CAS) are introduced. CAS is implemented in the ship-handling simulator of MOERI. The performance of CAS is tested on the situation of open sea with 3 traffic ships, whose position is assumed to be informed from AIS. Own-ship is fully autonomously navigated by autopilot including the collision avoidance algorithm, CAS. Experimental results show that own-ship can successfully avoid the collision against traffic ships and the calculated courses from CAS are reasonable.

• Journal of radiological science and technology
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• v.40 no.3
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• pp.363-370
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• 2017

We aimed to evaluate the physical imaging properties in various digital radiography systems with charged coupled device (CCD), computed radiography (CR), and indirect flat panel detector (FPD). The imaging properties measured in this study were modulation transfer function (MTF) wiener spectrum (WS), and detective quantum efficiency (DQE) to compare the performance of each digital radiography system. The system response of CCD were in a linear relationship with exposure and that of CR and FPD were proportional to the logarithm of exposure. The MTF of both CR and FPD indicated a similar tendency but in case of CCD, it showed lower MTF than that of CR and FPD. FPD showed the lowest WS and also indicated the highest DQE among three systems. According to the results, digital radiography system with different type of image receptor had its own image characteristics. Therefore, it is important to know the physical imaging characteristics of the digital radiography system accurately　to obtain proper image quality.

• Progress in Superconductivity
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• v.8 no.1
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• pp.33-39
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• 2006

We have developed a second-order double relaxation oscillation SQUID(DROS) gradiometer with a baseline of 35 mm, and constructed a poorly magnetically-shielded room(MSR) with an aluminum layer and permalloy layers for magnetocardiography(MCG). The 2nd-order DROS gradiometer has a noise level of 20 $fT/{\surd}Hz$ at 1 Hz and 8 $fT/{\surd}Hz$ at 200 Hz inside the heavily-shielded MSR with a shielding factor of $10^3$ at 1 Hz and $10^4-10^5$ at 100 Hz. The poorly-shielded MSR, built of a 12-mm-thick aluminum layer and 4-6 permalloy layers of 0.35 mm thickness, is 2.4mx2.4mx2.4m in size, and has a shielding factor of 40 at 1 Hz, $10^4$ at 100 Hz. Our 64-channel second-order gradiometer MCG system consists of 64 2nd-order DROS gradiometers, flux-locked loop electronics, and analog signal processors. With the 2nd-order DROS gradiometers and flux-locked loop electronics installed inside the poorly-shielded MSR, and with the analog signal processor installed outside it, the noise level was measured to be 20 $fT/{\surd}Hz$ at 1 Hz and 8 $fT/{\surd}Hz$ at 200 Hz on the average even though the MSR door is open. This result leads to a low noise level, low enough to obtain a human MCG at the same level as that measured in the heavily-shielded MSR. However, filters or active shielding is needed fur clear MCG when there is large low-frequency noise from heavy air conditioning or large ac power consumption near the poorly-shielded MSR.

• Journal of Korean Society of Transportation
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• v.27 no.4
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• pp.63-76
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• 2009

On the basis of a Stochastic Frontier Approach (SFA), this paper analyses revenue efficiencies for the same sample of Korean and Japanese railways in the papers which analyze cost efficiencies using a generalized translog functional form. The paper also compares the results of revenue efficiencies with cost efficiencies and evaluates the effects of managerial autonomy and privatization on the firm-specific efficiencies. The results show that the average estimate of revenue inefficiency is 7.02% when the term of inefficiency is assumed to be distributed as a half-normal and 6.98% as a exponential for the total sample. Also, standardized inefficiencies in revenues (7.5%) are greater than those in costs (2.1%). JR East and JR West are found to be most efficient on the revenue side and on the cost side respectively while JNR and JR Kyushu are worst efficient on the both sides. Finally, the correlations between efficiencies in revenues and costs also between efficiencies and privatization are positively correlated. The results suggest that the most independent companies, with increased managerial autonomy via privatization, are the most efficient in both revenues and costs.

• Journal of the korean society of oceanography
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• v.37 no.3
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• pp.91-107
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• 2002

The wintertime upwind flow in the Yellow Sea has been investigated through a series of two-dimensional numerical experiments in an idealized basin. A total of 10 experiments have been carried out to examine the effects of wind forcing, bottom friction and the presence of oceanic currents sweeping the shelf of the East China Sea. A spatially uniform steady and periodic wind stresses are considered along with comparison of linear and quadratic formulations. The wind-driven flow in the absence of oceanic current has been computed using Proudman open boundary condition (POBC), while the wind-driven current in the presence of oceanic current has been computed using Flather’s radiation condition (FOBC). The oceanic currents to be prescribed at the open boundary have been simulated by specifying uniform sea level gradients across the Taiwan Strait and the eastern ECS shelf, Calculations show that, as seen in Lee et al. (2000), oceanic flow little penetrates into the Yellow Sea in the absence of wind forcing unless a unrealistically low rate of bottom frictional dissipation is assumed. Both steady and time-periodic wind stresses invoke the upwind flow along the central trough of the Yellow Sea, independently of the presence of the oceanic current. The presence of oceanic currents very marginally alters the north-south gradient of the sea surface elevation in the Yellow Sea. Changes in the intensity and direction of the wind-induced mean upwind flow are hardly noticeable in the Yellow Sea but are found to be significant near Cheju Island where the gradient is reduced and therewith contribution of Ekman transport increases. In case of steady wind forcing circulation patterns such as two gyres on the slope sides, a cyclonic gyre on the western slope and an anticyclonic gyre on the eastern slope persist and the upwind flow composes part of the cyclonic gyre in the Yellow Sea. While in case of the time-periodic wind stress the appearance and disappearance of the patterns are repeated according to the time variation of the wind stress and the upwind flow accordingly varies with phase delay, mostly intensifying near the time when the wind forcing is approximately near the middle of the decaying stage.

• Parasites, Hosts and Diseases
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• v.49 no.1
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• pp.85-90
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• 2011

Relatively little has been studied on the AMA-1 vaccine against Plasmodium vivax and on the plasmid DNA vaccine encoding P. vivax AMA-1 (PvAMA-1). In the present study, a plasmid DNA vaccine encoding AMA-1 of the reemerging Korean P. vivax has been constructed and a preliminary study was done on its cellular immunogenicity to recipient BALB/c mice. The PvAMA-1 gene was cloned and expressed in the plasmid vector UBpcAMA-1, and a protein band of approximately 56.8 kDa was obtained from the transfected COS7 cells. BALB/c mice were immunized intramuscularly or using a gene gun 4 times with the vaccine, and the proportions of splenic T-cell subsets were examined by fluorocytometry at week 2 after the last injection. The spleen cells from intramuscularly injected mice revealed no significant changes in the proportions of CD8$^+$ T-cells and CD4$^+$ T-cells. However, in mice immunized using a gene gun, significantly higher (P<0.05) proportions of CD8$^+$ cells were observed compared to UB vector-injected control mice. The results indicated that cellular immunogenicity of the plasmid DNA vaccine encoding AMA-1 of the reemerging Korean P. vivax was weak when it was injected intramuscularly; however, a promising effect was observed using the gene gun injection technique.

• Journal of the Korean Wood Science and Technology
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• v.28 no.1
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• pp.55-64
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• 2000

Culture maturity assessment can be used to control fruiting body flush timing. Culture maturity of sawdust-based substrate was evaluated by using oak mushroom, (Lentinula edodes (Berk.) Pegler). The influence of substrate water potential (${\psi}$) on the growth and fruiting of three genotypes of L. edodes was also investigated. Glucosamine content revealed a peak at the fruiting body senescent stage. Glucosamine increased steadily to the sporophore senescent stage, and sharply declined at crop treatment. Lipid phosphate and ergosterol contents peaked at pinning and button break stages, respectively. Therefore lipid phosphate and ergosterol contents would be considered as the convenient measurement for judging culture maturity and fruiting potentials. The substrate pH values before inoculation and on the fruiting stage were varied from 6.3 to 4.0. This pH changes were detected as changes in color from bluish purple to yellow by direct bromphenol blue(BPB) spraying, and shown a good correlation with fruit body yield of the 1 st flush. Concerning water potential of the cultures, a slight reduction of water potential, -0.5MPa, stimulated mycelial and colony growths on liquid, agar and sawdust-based substrates. The water potential of well-colonized matured substrate was -0.7MPa and -4.0MPa, before and after the fruiting, respectively. Excellent water providing capacity (higher ${\psi}$) is expected to well-matured cultures with a high density of mycelial colonization. Also, the substrate water potential significantly affected by the interaction between genotypes and spawn run time.

• Journal of radiological science and technology
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• v.39 no.3
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• pp.435-441
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• 2016

The importance of radiation dose display of medical X-ray equipment was emphasized, while third edition of IEC(International Electrotechnical Commission) 60601 started to apply. The existing medical X-ray equipment selected a method for attaching the DAP(Dose Area Product) meter when the dose display. However, because the DAP meter was dependent on all of the income, And it did not yet produced in Korea. So, we received the support of Seoul R&BD Program(Grants No. C1152055) to produce DAP meter prototype of the Domestically technology. In this study, the performance of this prototype was evaluated by comparing the German company's product Evaluation item was an electronic capture performance, radiation dose dependence, radiation quality dependence, energy transmittance, repeatability, light transmittance of 6 entries. And IEC 60580 was based on this evaluation. Evaluation results were electronic capture performance intrinsic error 9.5%, radiation dose dependence limits of variation 1%, repeatability coefficient of variation 2%, energy transmittance 91% each assessment was passed. However radiation quality dependence limits of variation 29%, light transmittance 55% was less than acceptance criteria.

• Applied Biological Chemistry
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• v.49 no.2
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• pp.135-139
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• 2006

This study was carried out to investigate the cosmeceutical activities of Persicae semen. Cosmeceutical activities include anti-oxidant, tyrosinase inhibition effects and nitrite scavenging ability. The Persicae semen was divided into three parts, Bean of Persicae semen (BPS), Shell of Persicae semen (SPS) and Nibs of Persicae semen (NPS). In the electron donating ability test, 1,000ppm of water extract from BPS showed an effect of 89%, while 1,000 ppm of ethanol extract from SPS showed an effect of 87%. These results are higher compared to those of BHA at the equal concentration. We were able to get an effect of 98% from all of Persicae semen ethanol extract of 10,000 ppm in the tyrosinase inhibition test. Nitrite scavenging ability test, ethanol extract from BPS was decreasing to 96% by addition of 1,000ppm. According to these results, we find that Persicae semen applicable to advanced material for cosmetics. From the above results, it was confirmed that Persicae semen could be used in functional cosmetics.