• Progress in Superconductivity
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• v.8 no.2
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• pp.152-157
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• 2007

Uniaxial square Helmholtz coils for testing SQUID sensors were designed and their field distributions were calculated. Optimum parameters for maximizing the uniform region in the Helmholtz mode were obtained for different uniformity tolerances. The coil system consists of 2 pairs of identical square loops, a Helmholtz pair for generating uniform fields and the other for the 2nd-order gradient fields in combination with the Helmholtz pair. Full expressions of the axial component of the field were calculated by using Biot-Savart's law. To understand the behavior of the field near the coil center, analytical expressions were obtained up to the 4th-order in the midplane and along the coil axis. The Helmholtz condition for generating uniform fields was calculated to be $d/{\alpha}=0.544505643$, where 2d is the inter-coil distance and $2{\alpha}$ is the side length of the coil square. Maximized uniform range can be obtained for a given nonuniformity tolerance by choosing $d/{\alpha}$ slightly lower than the Helmholtz condition. The pure second-order gradient field can be generated by subtracting the Helmholtz field from the field of the 2nd pair with equal magnitudes of the center fields of the two pairs. The coil system is useful for testing balance and sensitivity of SQUID gradiometers.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.44 no.2
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• pp.118-125
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• 2011

In this study, an angiotensin I-converting enzyme (ACE) inhibitor from squid skin was purified and characterized. Squid (Todarodes pacificus) skin protein isolates were hydrolyzed using six commercial proteases: alcalase, ${\alpha}$-chymotrypsin, neutrase, papain, pepsin, and trypsin. The peptic hydrolysate had the highest ACE inhibitory activity. The ACE inhibitory peptide was purified using Sephadex G-25 column chromatography and reverse phase high-performance liquid chromatography (HPLC) with a $C_{18}$ column. The purified ACE inhibitory peptide was identified and sequenced, and found to consist of seven amino acid residues: Ser-Ala-Gly-Ser-Leu-Val-Pro (657Da). The $IC_{50}$ value of the purified ACE inhibitory peptide was 766.2 ${\mu}M$, and Lineweaver-Burk plots suggested that the purified peptide acts as a noncompetitive ACE inhibitor. These results suggest that the ACE inhibitory peptide purified from the peptic hydrolysate of squid skin may be of benefit in developing antihypertensive drugs and functional foods.

• Progress in Superconductivity
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• v.11 no.2
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• pp.152-157
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• 2010

We have fabricated the low noise liquid helium(LHe) dewar with a different shape of thermal shield to apply the 64-channel SQUID(Superconducting Quantum Interference Device) gradiometer. The first shape of thermal shield was made of an aluminum plate with a wide width of 100 mm slit and the other shape was modified with a narrow width of 20 mm slit. The two types of dewars were estimated by comparing the thermal noise and the signal-to-noise ratio(SNR) of magnetocardiography(MCG) using the $1^{st}$ order SQUID gradiometer system cooled each dewar. The white noise was different as a point of the dewar. The noise was increased as close as the edge of dewar, and also increased at the thermal shield with the more wide width slit. The white noise of the dewar with thermal shield of 100 mm slit was 6.5 fT/$Hz^{1/2}$ at the center of dewar and 25 fT/$Hz^{1/2}$ at the edge, and the white noise of the other one was 3.5 - 7 fT/$Hz^{1/2}$. We measured the MCG using 64-channel SQUID gradiometer cooled at each LHe dewar and compared the SNR of MCG signal. The SNR was improved of 10 times at the LHe dewar with a modified thermal shield.

• Progress in Superconductivity and Cryogenics
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• v.15 no.2
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• pp.20-23
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• 2013

For sensitive measurements of micro-Tesla nuclear magnetic resonance (${\mu}T$-NMR) signal, a low-noise superconducting quantum interference device (SQUID) system is needed. We have fabricated a liquid He dewar for an SQUID having a large diameter for the pickup coil. The initial test of the SQUID system showed much higher low-frequency magnetic noise caused by the thermal magnetic noise of the aluminum plates used for the vapor-cooled thermal shield material. The frequency dependence of the noise spectrum showed that the noise increases with the decrease of frequency. This behavior could be explained from a two-layer model; one generating the thermal noise and the other one shielding the thermal noise by eddy-current shielding. And the eddy-current shielding effect is strongly dependent on the frequency through the skin-depth. To minimize the loop size for the fluctuating thermal noise current, we changed the thermal shield material into insulated thin Cu mesh. The magnetic noise of the SQUID system became flat down to 0.1 Hz with a white noise of 0.3 $fT/{\surd}Hz$, including the other noise contributions such as SQUID electronics and magnetically shielded room, etc, which is acceptable for low-noise ${\mu}T$-NMR experiments.

• Journal of KIISE:Computing Practices and Letters
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• v.8 no.4
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• pp.450-456
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• 2002

Open source web service softwares are usually running on UNIX-based operating systems. Choosing an operating system can affect web system performance. In this paper, we describe a source - code-level time measurement tool and measure a service time of each system call that Squid - open source web proxy cache - makes. We run Squid 2.4.STABLEl on Linux 2.4.2 and Solaris 8, and we compare the measured time. As a result, Linux 2.4.2 performs better than Solaris 8. It can be used as a guide for selecting system software on building web service using open source software, and also be used as a basis for enhancing the operating system performance of supporting web service software.

• Corrosion Science and Technology
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• v.3 no.5
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• pp.222-225
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• 2004

A portable RF HTS SQUID-based susceptometer was applied to the measurement of fatigue behavior for type 316L(N) stainless steel containing 0.04% to 0.15% nitrogen content. Strain-controlled low cycle fatigue (LCF) tests were conducted at RT and $600^{\circ}C$ in air an atmosphere, and the magnetic moments were measured after the fatigue test using HTS SQUID. The magnetic moment of an as-received sample is higher than that of a fatigued sample in all the temperature ranges irrespective of the nitrogen content. The fatigue life decreased with an increasing test temperature up to $500^{\circ}C$, but increased at $600^{\circ}C$. The change of the magnetic moments by LCF test is attributed to the stress induced micro defects.

• International journal of advanced smart convergence
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• v.8 no.2
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• pp.68-76
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• 2019

In this study, we propose a squid jeotgal, Korean fermented seafood, supplement with different soy isoflavones supplements, followed by fermentation for different time intervals at $4^{\circ}C$ to increase the antioxidant activity and improve the food value. In the first month, fermented jeotgals with at lowconcentration ($2mg\;g^{-1}$) of added soy isoflavones showed a significant increase in the activity of up to 55%, whereas, at high concentration ($10mg\;g^{-1}$), the activity almost doubled compared to that of the sample without isoflavones. Moreover, the squid enriched with isoflavones also exhibited significantly decreased total volatile base nitrogen, thiobarbituric acid reactive substances, and biogenic amines, indicative of higher inhibition of the formation of these substances. The changes in the microbial profile were also evaluated. This use of soy isoflavanones as an additive could aid in improving the nutritional value of fermented seafood to reduce the incidence of age-related and chronic disorders.

• Progress in Superconductivity and Cryogenics
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• v.9 no.2
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• pp.1-6
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• 2007

As very sensitive magnetic field sensors, superconducting quantum interference devices (SQUIDs) are used to measure magnetic field signals from the human heart. By analyzing these cardiomagnetic signals, functional diagnoses of heart can be done. In order to measure weak biomagnetic signals, we need a multichannel SQUID array with sensor coverage large enough to cover the whole heart to enable the measurement in a single position setting. In this paper, we review the recent development of SQUID systems for measuring cardiomagnetic fields, with special emphasis on SQUID types.

• Korean Journal of Acupuncture
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• v.23 no.4
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• pp.135-145
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• 2006

Objectives and Methods : Using the 2-channel DROS SQUID (Korea Research Institute of Standards of Science, 1999), the present study was carried out to record changes elicited in the auditory cortex by acupuncture stimulus on right TE5 (Waiguan) and GB43 (Xiaxi). Needle-retention stimulation of TE5 and GB43 were done for acquiring the brain activities changed by acupuncture. Acupoint TE5 and GB43 is known to be effective for the treatment of ear-related disease, such as deafness and tinnitus, and to be suspected to be related to the auditory cortex. Auditory evoked magnetic fields were recorded hem the left hemisphere of five subjects, in response to contralateral ear stimulation by irregularly spaced 170 msec long 1kHz tone busts (Korea Research Institute of Standards of Science) Results and Conclusions : The result as follows. The latency and amplitude of SQUID MEG responses at the human auditory cortex changed by needle-retention condition on TE5 were 4msec and 9.2 fT, respectively, which were slower and smaller than those of no-acupuncture condition. The latency and amplitude of SQUID MEG responses at the human auditory cortex changed by needle-retention condition on GB43 were 7.2 msec and 1.6 fT, respectively, which were slower and larger than those of no-acupuncture condition. The latency of SQUID MEG responses at the human auditory cortex changed by needle-retention condition on GB43 condition was slower than that of TE5 acupuncture condition.

• Progress in Superconductivity
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• v.13 no.3
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• pp.139-145
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• 2012

Electric activity of cardiac muscles generates magnetic fields. Magnetocardiography (or MCG) technology, measuring these magnetic signals, can provide useful information for the diagnosis of heart diseases. It is already about 40 years ago that the first measurement of MCG signals was done by D. Cohen using SQUID (superconducting quantum interference device) sensor inside a magnetically shielded room. In the early period of MCG history, bulky point-contact RF-SQUID was used as the magnetic sensor. Thanks to the development of Nb-based Josephson junction technology in mid 1980s and new design of tightly-coupled DC-SQUID, low-noise SQUID sensors could be developed in late 1980s. In around 1990, several groups developed multi-channel MCG systems and started clinical study. However, it is quite recent years that the true usefulness of MCG was verified in clinical practice, for example, in the diagnosis of coronary artery disease. For the practical MCG system, technical elements of MCG system should be optimized in terms of performance, fabrication cost and operation cost. In this review, development history, technical issue, and future development direction of MCG technology are described.