• 한국포장학회지
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• 제4권1호
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• pp.17-21
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• 1997

Zeolite powder used by molecular sieve, adsorbants and catalist. 1N HCl teated zeolite powders for freshness extension of fruits and vegetables showed that specific surface area was $300.29m^2/g$ largest then that of the others, and ethylene gas adsorbability was 29.07 cc/g. And then 0.5N NaCl Henting after 1N HCl treated zeolite powder showed that specific surface area and ethylene gas adsorbability was $329.43m^2/g$ and 35.64 cc/g largest then those of the others. Specific surface area of processed zeolite powder treated by high intensity magnetic seperator(HIMS) showed $369.67m^2.g$, ethylene gas adsorbability was 39.87cc/g. In this study, it could be employ 0.5N NaCl treat and HIMS methods as MA packaging materials for freshess extension of fruits and vegetables.

• Journal of Welding and Joining
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• 제16권1호
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• pp.70-76
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• 1998

Most fossil power plants and many critical components will be approaching the end of their nominal design life. At the same time, utilities are finding it economically attractive to extend the use of these plants for several more years, Especially Main steam pipe that operated under high temperature and pressure, often under the more severe operating conditions associated with cycling duty, is most important pipe system and critical component in fossil power plant. To extend the viability of older pipe system and to improve the operation and maintenance reliability, some technologies of precise diagnosis and life management have evolved out of the necessity. The purpose of this study is to descrive the related technologies and show the example of one power plants. The purpose of this study is to descrive the related technologies and show the example of one power plants. The stress analysis was done using ANSYS FEM Code. The branch area from main steam to turbine was the high stressed zone. To evaluate the degradation of the pipe material, replica, visual check, magnetic test, hardness test were done at the welding spot. The degradation level of welding point was E/F, so the remaining life of the welded area was about 0-25%.

• 한국소음진동공학회논문집
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• 제22권6호
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• pp.582-587
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• 2012

This paper presents a solution of the vibration reduction in the hollow shafts by using magentorehological( MR) elastomer. Proposed active damping structure is built by embedding the MR elastomers whose elastic modulus is controllable by an applied magnetic field. MR elastomers consist of synthetic rubber filled with micron-sized magnetizable particles. For reduction of vibration, dynamic damper of hollow shaft is designed by using MR elastomer and equipped in the hollow shaft for the application to drive shaft. Experiment results are shown through the experiments to confirm the effect of MR elastomer dynamic damper for vibration reduction. Thus, the designed damping structure can be applied to vibration absorber used in drive shafts as well as the propeller shafts.

• 한국정보통신학회논문지
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• 제11권10호
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• pp.1986-1991
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• 2007

본 논문에서 지구자기장을 측정하여 방위를 결정하는 자기 저항 소자의 경사각의 이상 현상에서 있어 예측할 수 없는 특성에 대해 불확실성에서의 추론을 통해 센서로서의 안정성을 확보하는데 그 목적이 있다. 따라서 퍼지 알고리즘을 적용하여 외부 환경 변화에 민감하게 변화하는 소자의 왜곡현상을 프로그래밍 적인 요소를 실험하여 센서의 왜율적인 요소에서 벗어남을 보인다. 나아가 소자의 고속, 고신뢰성을 갖는 응용에 사용할 수 있음을 보인다.

• 대한설비공학회:학술대회논문집
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• 대한설비공학회 2006년도 하계학술발표대회 논문집
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• pp.162-167
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• 2006

Nanofluid is a kind of new engineering material consisting of nanoparticles dispersed in base fluid. Nanofluids could have various applications such as magnetic fluids, heat exchanger working fluids, lubricants, drug delivery and so on in present study, various nanoparticles, such as MWCNT (Multi-walled Carbon Nanotube), fullerene, copper oxide, and silicon dioxide are used to produce nanofluids. As base fluids, DI-water, ethylene glycol, oil, and silicon oil are used. To investigate the thermo-physical properties of nanofluids, thermal conductivity and kinematic viscosity are measured. Stability estimation of nanofluid is conducted with UV-vis spectrophoto-meter. In this study, the high pressure homogenizer is the most effective method to produce nanofluid with the prepared nanoparticle and base fluid. Excellently stable nanofluids are produced with the magnetron sputtering system. Thermal conductivity of nanofluid increases with increasing particle volume fraction except water-based fullerene nanofluid which has lower thermal conductivity than base fluid due to its lower thermal conductivity, 0.4 W/mK. The experimental results can't be predicted by Jang and Choi model.

• 한국자기학회지
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• 제5권5호
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• pp.515-518
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• 1995

We have studied the magnetization in fields up to 1T at 5K, the saturation magnetization dependence on temperature and the temperature dependence of AC-susceptibility at very low fields (5mOe to 50mOe) of glassy $Fe_{91-x}Zr_{7}B_{2}Ni_{x}$ (x = 0, 5, 10, 15) alloys. The temperature dependence of the magnetization follows the predictions of spin wave excitations with long wavelengths. At zero Ni concentration there is a clear competition between ferromagnetic and antiferromagnetic interactions giving rise to spin-glass behaviour. The addition of Ni drastically modifies the magnetic properties: the antiferromagnetic exchange coupling is reduced and finally disappears, the spin wave stiffness increases from 39.5 to $87.3\;meV{\AA}^{2}$ and To increases from 230 K to 478 K. We develop a simple model to quantify the competing interactions and to relate the antiferromagnetically coupled Fe moments to the Ni concentration. We find that the initial susceptibility increases with increasing Ni content along with a decrease of the temperature dependence.

• 한국자기학회지
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• 제5권6호
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• pp.956-962
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• 1995

본 연구에서는 포화지방산으로 피복된 초미립 마그네타이트(Magnetite, Fe$_{3}$ $O_{4}$) 중에 nonanoic acid가 용해되어 있는 알칼리 수용액을 첨가한 후, 이들 슬러리(slurry)를 건조하여 kerosene에 분산시켜 유상자성유체를 제조하였다. Stearic acid 첨가량에 따른 분산율의 변화를 조사한 결과 stearic acid 첨가량이 증가함에 따라 분사율은 증가하였으나, 2.6 * $10^{-2}$ mol 이상에서는 분산율이 78%로 감소하 였다. Stearic acid로 피복된 마그네타이트에 의해 유상자성유체제조시 분산안정제로서 사용된 nonanoic acid 첨가량에 따른 분산율의 변화를 조사한 결과 nonanoic acid 를 첨가하지 않은 경우 분산이 일어나지 않았으나, nonanoic acid를 첨가함에 따라 분산율은 급격히 증가하였다. 포화지방산을 계면활성제로 사용하여 흡착-유기상 분산 법에 의해 유상자성유체를 제조한 결과, $C_{12}$ ~ $C_{16}$ 지방산을 사용하여 유상자성유체를 제조할 경우 20% 내외의 분산율을 나타내었다. 분산제로서 Nonanoic acid를 사용하여 유상자성유체를 제조할 경우 $C_{10}$ 지방산으로 제조한 유상자성 유체는 분산이 일어나지 않았으나, C 사슬의 길이가 증가함에 따라서 분산율은 급격히 증가하였으며 $C_{15}$ 지방산 부터는 90% 이상의 분산율을 나타내었다.

• Journal of Yeungnam Medical Science
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• 제38권2호
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• pp.148-151
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• 2021

Pudendal nerve entrapment (PNE) syndrome refers to the condition in which the pudendal nerve is entrapped or compressed. Reported cases of PNE associated with ganglion cysts are rare. Deep gluteal syndrome (DGS) is defined as compression of the sciatic or pudendal nerve due to a non-discogenic pelvic lesion. We report a case of PNE caused by compression from ganglion cysts and treated with steroid injection; we discuss this case in the context of DGS. A 77-year-old woman presented with a 3-month history of tingling and burning sensations in the left buttock and perineal area. Ultrasonography showed ganglion cystic lesions at the subgluteal space. Magnetic resonance imaging revealed cystic lesions along the pudendal nerve from below the piriformis to the Alcock's canal and a full-thickness tear of the proximal hamstring tendon. Aspiration of the cysts did not yield any material. We then injected steroid into the cysts, which resolved her symptoms. Steroid injection into a ganglion cyst should be considered as a treatment option for PNE caused by ganglion cysts.

• Current Applied Physics
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• 제18권11호
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• pp.1381-1387
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• 2018

One dimensional (1D) grating has been fabricated (using focused ion beam) on 50 nm gold (Au) film deposited on higher refractive index Gallium phosphate (GaP) substrate. The sub-wavelength periodic metal nano structuring enable to couple photon to couple with the surface plasmons (SPs) excited by them. These grating devices provide the efficient control on the SPs which propagate on the interface of noble metal and dielectric whose frequency is dependent on the bulk electron plasma frequency of the metal. For a fixed periodicity (${\Lambda}=700 nm$) and slit width (w = 100 nm) in the grating device, the efficiency of SPP excitation is about 40% compared to the transmission in the near-field. Efficient coupling of SPs with photon in dielectric provide field localisation on sub-wavelength scale which is needed in Heat Assisted Magnetic recording (HAMR) systems. The GaP is also used to emulate Vertical Cavity Surface emitting laser (VCSEL) in order to provide cheaper alternative of light source being used in HAMR technology. In order to understand the underlying physics, far-and near-field results has been compared with the modelling results which are obtained using COMSOL RF module. Apart from this, grating devices of smaller periodicity (${\Lambda}=280nm$) and slit width (w = 22 nm) has been fabricated on GaP substrate which is photoluminescence material to observe amplified spontaneous emission of the SPs at wavelength of 805 nm when the grating device was excited with 532 nm laser light. This observation is unique and can have direct application in light emitting diodes (LEDs).

• Journal of Applied Biological Chemistry
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• 제63권4호
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• pp.335-338
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• 2020

Artemisia iwayomogi (Compositae), a perennial mugwort, is native to Korea and widely distributed in Japan, Russia, and China. A. iwayomogi and A. capillaris are similar in morphology and pharmacological activity and have been used for the same medicinal purposes in Korea. While various ingredients such as coumarins and flavonoids and their activity studies have been reported for A. capillaris, few studies have been conducted on the pharmacologically active components of A. iwayomogi. In Korea, A. capillaris is not economical because only young leaves are used as a medicinal material. Because of this, A. iwayomogi is frequently used in Korea, indicating the need to study its pharmacologically active components. Therefore, a phytochemical study was initiated to isolate active compounds from the aerial parts of A. iwayomogi. Finally, four coumarins, umbelliferone (1), esculetin (2), grevillone (3), and scoparone (4) were isolated for the first time from the aerial parts of A. iwayomogi in this study.