• Membrane Journal
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• v.29 no.4
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• pp.191-201
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• 2019

Before the commercialization of polymeric membranes applicable for industrial application, the homework remains for the high-performance polymers to overcome the practical challenge: long-term stability for prolonged service time. Polymers of intrinsic microporosity (PIMs), exhibiting exceptionally high fractional free volume and high permeability, are susceptible to physical aging where the extra volume created by the inefficient ladder-type packing will lead them from the volumetric equilibrium and reduce the free volume/permeability over time. Here, we will re-examine the physical aging of polymers of intrinsic microporosity, and discuss some of the most prominent attempts to mitigate physical aging in PIMs.

• Clean Technology
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• v.14 no.4
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• pp.248-255
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• 2008

The volume expansion of three ionic liquids (ILs) in the presence of supercritical carbon dioxide has been measured at pressures up to 32 MPa and at temperatures from 313.15 to 333.15 K in a high-pressure view cell. The imidazolium-derivative ionic liquids 1-butyl-3-methylimidazolium hexafluorophosphate ([bmim][$PF_6$]), 1-butyl-3-methylimidazolium tetrafluoroborate ([bmim][$BF_4$]), and 1-octyl-3-methylimidazolium tetrafluoroborate ([omim][$BF_4$]) were employed in this research. The effects of pressure, temperature, nature of anion and cation as well as the water content on the volume expansion of ILs by absorbing $CO_2$ were investigated experimentally. The volume expansion was higher for the ILs with longer cationic alkyl group and for the ILs with lower anion polarity. The lower the water content, the lower the temperature, or the higher the pressure, the higher was the expansion of IL phase.

• The Korean Journal of Rheology
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• v.6 no.1
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• pp.49-59
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• 1994

높은 전기장 하에서 다분산, 비구형 실리카/실리콘 오일 현탁액의 전기유변 (electrorheological, ER)현상을 살펴 보았다. 전기유변유체는 전기장 방향으로 사슬구조를 형 성하는 특성을 보이며 이것이 유변물성의 향상에 기여하는 것으로 알려졌다. 동적(dynamic) 상태 실험에서 전기장 하의 실리카 현탁액은 매우낮은 임계변형율(${\gamma}$c =0.1%)이상에서 비선 형 점탄성을 보였다. 저장탄성계수(G＇)는 변형율 변화에 손실탄성계수(G＂)는 매질의 점도 에 더 민감한 의존성을 보였다. 또한 겉보기 항복응력은 입자의 부피분율과 전기장에$\Phi$1.9E1.4 의 의존성을 보였는데 부피분율에 대한 의존성이 큰 이유는 0.1 이상의 부피분율에서 복합 사슬 구조 내의 입자들 간의 상호 정전효과가 지배적으로 나타나기 때문이라고 생각된다. 정상상태 실험에서는 부피분율이 크거나 높은 전기장 하에서 전단속도가 0.1sec-1 정도 이하 로 감소함에 따라 전단응력이 급겨히 증가하는 현상을 보였다. 그러므로 본질적인 동적 항 복응력을 얻기 위해서는 매우 낮은 전단속도 영역의 특이한 응력거동을 고려해야한다. 큰 전단속도 하에서는 hydrodynamic interaction의 영향으로 전단속도의 증가에 따라 전단응력 이 증가하였다. 이같은 전단응력의 거동을 계단전단실험으로 확인하였다.

• Journal of Korean Ophthalmic Optics Society
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• v.21 no.2
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• pp.137-146
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• 2016

Purpose: The relationship between retinal conditions such as macular thickness and retinal volume of the eyes with central serous chorioretinopathy(CSC) and visual acuity was investigated. Methods: A total of 136 eyes from 78 subjects was divided into 5 groups: CSC eyes under treatment and its asymptomatic contralateral eyes, fully cured CSC eyes after the diagnosis and its contralateral, and normal eyes. Their uncorrected visual acuity(UCVA), best corrected visual acuity(BCVA), retinal thickness and retinal volume were further examined. Results: All of UCVA, BCVA, retinal thickness and retinal volume of CSC eyes under treatment were significantly different from those of asymptomatic contralateral eyes, fully cured CSC eyes and normal eyes. BCVA of the asymptomatic contralateral eyes was not significantly different from it of normal eyes, however, its retinal thickness and volume were significantly different from those of normal eyes. Increased degree of retinal volume along with the increase of retinal volume was greater in CSC eyes and its asymptomatic contralateral eyes, fully cured CSC eyes and its contralateral eyes than normal eyes. Conclusions: From the present study, it was revealed that the retinal thickness and volume of asymptomatic contralateral eyes of CSC increase as well as CSC eyes, and the change of BCVA due to CSC occurs only when the retinal thickness and volume increase in some extent.

• Journal of the Korean Society of Radiology
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• v.15 no.6
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• pp.821-831
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• 2021

In order to calibrate energy and efficiency using the PENELOPE Code, a PENELOPE simulation was performed using a volume source. Here, we want to verify peak efficiency and usefulness by performing simultaneous measurement and correction. calculate the coincident sum correction for all volumes, first subdivide the volumes of the cylinder and the four Marinelli beakers into three heights again. Therefore, the simultaneous measurement correction coefficient in three areas and the simultaneous measurement correction coefficient for the entire volume source are calculated as output. At low energies, the j value for each source volume (50-300 ml) is small and increases significantly in the high energy range. Simulation results showed good agreement within 2.5% for all source volumes except for 50 ml and 300 ml, which were up to 4%. This means that the correction for the simultaneous measurement effect during measurement is effective. In addition. Based on this, it can be confirmed that there is an advantage to improve the detection efficiency when measuring various sources and environmental samples.

• The Korean Journal of Nuclear Medicine
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• v.35 no.3
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• pp.152-160
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• 2001

Purpose: We tried to establish the reproducibility of the measurement of maximal elastance (Emax) and to compare the degree of the reproducibility of two estimation methods: single pressure-volume loop method and parameter optimization method. Materials and methods: In 47 patients (42 males and 5 females, $53{\pm}10$ years old) with suspected coronary artery disease (election fraction; 22-68%), gated Tc-99m MIBI myocardial SPECT and arterial tonometry were acquired. In 11 patients among these 47 patients, gated SPECT and tonometry were performed twice consecutively with patients in situ. Emax and void volume (Vo) were estimated using single pressure-volume loop method of Lee and parameter optimization method based on linear approximation of Yoshizawa. Correlation between the consecutive measurements by each method and correlation between the two estimation methods were compared. Results: Reproducibility of Emax (r=0.96) and Vo (r=0.99) by single pressure-volume method was better than the reproducibility of Emax (r=0.89) and Vo (r=0.64) by parameter optimization method. Correlations of Emax and Vo were fair between the two methods. The correlation of Emax (r=0.77) was better than that of Vo (r=0.55). Conclusion: Reproducibility of Emax measurement by single pressure-volume loop method using gated myocardial SPECT and arterial tonometry was excellent. Reproducibility by parameter optimization method was also fair but was less than that achieved by single pressure-volume method.

• Journal of the Korean Magnetics Society
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• v.13 no.2
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• pp.70-75
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• 2003

Non-linear anisotropic materials were used to simulate the effects of bulk tensile stress in 3D finite element analysis (FEA). FEA was used to calculate the effects of near and far-side racetrack pit depth and simulated bulk tensile stress on magnetic flux leakage (MFL) signals. The axial and radial MFL signals were depended on near and far-side racetrack pit depth and on the bulk stress, but the circumferential MFL signal was not depended on them. The axial and radial MFL signals increased with greater pit depth and applied bulk stress, but the circumferential MFL signal was scarcely changed.

• Journal of the Society of Cosmetic Scientists of Korea
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• v.34 no.4
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• pp.333-338
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• 2008

The evaluation for the visage volume was performed with human and dummy face using PRIMOS $body^{(R)}$. Three researchers measured the dummy face attached different volume of clay (6.6 mL, 13.2 mL, and 19.8 mL). It is identified that the high correlation between measured values and real volume ($R^2=0.99$). The percent (%) of relative standard deviation (RSD) of the data was shown below 10%. In Gage R&R analysis, the percent of contribution, the percent of study variation and distinct categories values were 0.78%, 8.85%, and 15% respectively. Therefore this method was regarded as the good standard condition in aspect of reproducibility and repetitiveness of data. The face volume variation was measured by PRIMOS $body^{(R)}$ on the face in participated 10 healthy Korean women volunteers. Subjects used the product once a day for two weeks as night sleeping pack. After application of the test products, the 3D image data of face were taken 1 and 2 weeks later. We found the face volume was significantly decreased after using products. In conclusion, this novel non-invasive technique was useful in measuring and visualizing alterations in face volume as a consequence of certain treatments. This system will provide a rapid and precise analysis of 3D topographical information for face.

• Proceedings of the KIPE Conference
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• 2018.07a
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• pp.72-74
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• 2018

기존 자동차 및 트럭용 Jump Starter의 경우, 일반적인 자동차용 납축전지를 이용하여 사용하기 때문에 부피와 무게가 매우 커 휴대성이 어렵고, 고가의 제품군으로 형성되어 있어 일반 운전자들은 구입 및 사용하기 어려운 문제가 있다. 또한 리튬배터리를 이용한 Jump Starter의 경우, 부피는 줄었지만 원가가 매우 비싸고 주기적으로 충전을 하여 휴대해야하기 때문에 이용성에 불편함이 있고 실제 트럭이나 버스 같은 대용량 배터리는 Jump Starter가 구동을 하지 못하는 문제점이 있다. 본 논문은 자동차 및 트럭용 Jump Starter의 부피 및 원가를 최소화하면서 일반 운전자들도 휴대 가능한 편리성을 높이며, 대형트럭도 적용 가능한 건전지와 Super Capacitor를 이용한 초소형 저가형 Jump Starter 회로를 제안한다. 기존의 Jump Starter는 납축전지나 리튬전지를 사용하기 때문에, 전체적인 회로의 부피가 크고 무거우며 전체 제품의 원가가 증가하여 제품성이 떨어지는 단점이 있다. 또한 리튬전지를 사용하게 되면 주기적으로 충전을 해야 하기 때문에 소비자가 휴대 및 이용하기에 불편한 문제점도 있다. 반면 제안된 회로는 일반 소모용 건전지로도 Jump Starter 회로 구동이 가능하기 때문에, 운전자의 휴대성이 간편하고 언제 어디서든 소모용 건전지를 구매할 수 있기 때문에 운전자의 휴대성과 이용성이 매우 우수하다. 또한 순간적인 방전이 가능한 Super Capacitor를 이용하여 전체적인 회로의 부피 및 제품의 원가를 최소화 할수 있는 장점을 갖는다. 본 논문에서는 제안된 회로이 이론적인 특성을 분석하고 모의실험을 통해 확인하였으며, 실제 방전된 배터리 및 대형버스에 적용하여 실험을 통해 우수성을 검증하였다.

• Journal of the Korean Society of Radiology
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• v.81 no.6
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• pp.1377-1388
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• 2020

Purpose This study aimed to determine whether nasal septal deviation and concha bullosa affect the maxillary sinus volume, and whether this effect is associated with the prevalence of chronic sinusitis. Materials and Methods This study retrospectively reviewed 209 paranasal sinus CT (PNS CT) images of patients with sinonasal symptoms from January 2017 to December 2018. The maxillary sinus volume was measured twice by a radiologist, and statistical analysis was performed using SAS 9.4. Results Intersex comparison of the maxillary sinus volume (on left and right sides) revealed that the volume was significantly larger on both the sides (p < 0.0001) in men compared with that in women. Concha bullosa was found to occur mainly in the concave cavity of the septal deviation (p < 0.0001). No significant association was found between nasal septal deviation and maxillary sinusitis (p = 0.8756) as well as between concha bullosa and maxillary sinusitis prevalence (p = 0.3401) or maxillary sinus volume (both: p = 0.6289, Rt.: p = 0.9522, Lt.: p = 0.9201). Conclusion Although nasal septal deviation and the location of concha bullosa may affect each other, maxillary sinus volume and maxillary sinusitis were neither associated with nasal septal deviation nor concha bullosa.