• 한국토양비료학회지
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• 제46권6호
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• pp.549-555
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• 2013

Human influence on soil formation has dramatically increased as the development of human civilization and industry. Increase of anthropogenic soils induced research of those soils; classification, chemical and physical characteristics and plant growth of anthropogenic soils. However there have been no reports on soil pore properties from the anthropogenic soils so far. Therefore the objectives of this study were to test computer tomography (CT) to characterize physical properties of an anthropogenic paddy field soil and to find differences between natural and anthropogenic paddy field soils. Soil samples of a natural paddy field were taken from Ansung, Gyeonggi-do (Ansung site), and samples of an anthropogenic paddy field were from Gumi in Gyeongsangnam-do (Gasan) where paddy fields were remodeled in 2011-2012. Samples were taken at three different depths and analyzed for routine physical properties and CT scans. CT scan provided 3 dimensional images to calculate pore size, length and tortuosity of soil pores. Fractal analysis was applied to quantify pore structure within soil images. The results of measured physical properties (bulk density, porosity) did not show differences across depths and sites, but hardness and water content had differences. These differences repeated within the results of pore morphology. Top soil samples from both sites had greater pore numbers and sizes than others. Fractal analyses showed that top soils had more heterogeneous pore structures than others. The bottom layer of the Gasan site showed more degradation of pore properties than ploughpan and bottom layers from the Ansung site. These results concluded that anthropogenic soils may have more degraded pore properties as depth increases. The remodeled paddy fields may need more fundamental remediation to improve physical conditions. This study suggests that pore analyses using CT can provide important information of physical conditions from anthropogenic soils.

• 유기물자원화
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• 제25권3호
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• pp.63-71
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• 2017

본 연구에서는 활성탄 제조에 널리 이용되고 있는 KOH 활성화법으로 활성화된 활성탄의 표면적 증가를 위하여 세척시간, 교반속도, 세척횟수 등의 변수들에 대한 활성탄 세척공정 최적화 연구를 수행하였다. 연구결과, 활성탄의 표면적은 세척효율이 증가됨에 따라 뚜렷하게 증가되었는데, 90% 이상의 세척효율을 얻기 위해서는 활성탄의 복잡한 세공구조에 따른 세공 내 확산메커니즘이 제어인자로 작용함을 알 수 있었다. 또한, 세척액의 증발을 통하여 $K_2CO_3$를 얻을 수 있었고 이를 이용한 활성화실험이 이루어졌다. 그 결과, 비표면적 $2,219m^2/g$의 제조가 가능하였다. $K_2CO_3$가 KOH의 효과적인 대안이라는 것을 고려할 때, 활성탄 제조공정에서 폐수 재이용은 무배출 폐기물 공정에 적용 할 수 있음을 보여주었다.

• 수산해양기술연구
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• 제53권2호
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• pp.132-141
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• 2017

The objective of this study was to provide fundamental information on fish swimming behavioral properties. Acoustic data was collected at nighttime from the $10^{th}$ to $12^{th}$ March, 2016 near Yokji Island in the South Sea of South Korea, and was analyzed using the fish track technique. This technique is to identify groups of single targets, which shows a pattern of systematic movement. As a result, the differences of the behavioral properties such as depth, swimming speed, vertical direction, horizontal direction, tortuosity, and depth change among days were minor; however, statistical results (Welch analysis of variance) showed significant difference between days. Especially, the target strength (TS) of the $11^{th}$ were significantly different from the $10^{th}$ and $12^{th}$. It could be assumed that gizzard shad, which was the dominant species from the catch on the $11^{th}$ March, might have affected this difference. The correlation between TS and other properties was very week. The significant difference seemed even small differences of average values because of the large data volume.

• Parasites, Hosts and Diseases
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• 제51권6호
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• pp.695-701
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• 2013

Opisthorchis viverrini infection causes inflammation and liver injury leading to periductal fibrosis. Little is known about the pathological alterations in bile canaliculi in opisthorchiasis. This study aimed to investigate bile canalicular alterations in O. viverrini-infected hamsters and to examine the chemopreventive effects of curcumin on such changes. Hamsters were infected with O. viverrini and one group of animals was fed with 1% dietary curcumin supplement. Animals were examined during the acute infection phase, days 21 and 30 post-infection (PI) and chronic infection phase (day 90 PI). Scanning electron microscopy revealed that in the infected group fed with a normal diet, bile canaliculi became slightly tortuous by 30 day PI and more tortuous at day 90 PI. Transmission electron microscopy showed a reduction in microvilli density of canaliculi starting at day 30 PI, with a marked loss of microvilli at day 90 PI. These ultrastructral changes were slightly seen at day 21 PI, which was similar to that found in infected animals fed with 1% curcumin-supplemented diet. Notably, curcumin treatment prevented the reduction of microvilli density, reduced the dilation of bile canaliculi, and decreased the tortuosity of the bile canaliculi relative to non-infected animals on a normal diet at days 30 and 90 PI. These results suggest that curcumin reduces alteration of bile canaliculi and may be a promising agent to prevent the onset of bile duct abnormalities induced by O. viverrini infection.

• Journal of Korean Neurosurgical Society
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• 제53권4호
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• pp.213-217
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• 2013

Objective : Transradial angiography has become popular among many cardiologists as a diagnostic and therapeutic tool. However, transradial cerebral angiography is not utilized to the same extent. The purpose of this study is to present our experience regarding the usefulness of transradial cerebral angiography, especially in elderly patients. Methods : Between May 2011 and February 2012, a total of 126 cerebral angiographies were performed via a transradial approach in a single center. Of them, only 47 patients were over 60 years old. In our institution, we shifted the initial access from the right femoral artery to the right radial artery in all patients requiring cerebral angiography in 2011. We did not attempt radial access in 40 cases for variable reasons. Results : The procedural success rate was 92.2%. We have four failures of transradial angiography; two because of loop formations of the radial and brachial artery and two due to multiple puncture failures. All supra-aortic vessels were successfully catheterized. However, the selective catheterization rates of the left side distal vessels were lower, as success rates were 89.7% for the right internal carotid artery and 75% for the left internal carotid artery. Procedure-related vascular complications, such as puncture site hematoma, hand ischemia, pseudoaneurysm, arteriovenous fistula and arterial dissection were not observed in our series. However, intraprocedural thrombosis developed in one patient, which was resolved completely by intraarterial thrombolytic agents. Conclusion : With advancing patient's age, we believe that transradial cerebral angiography is a useful tool to decrease patient's discomfort and more effectively manage the vessel tortuosity.

• 한국전산유체공학회지
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• 제22권1호
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• pp.15-25
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• 2017

Swirl flow is often found in proximal coronary arteries, because the aortic valves can induce swirl flows in the coronary artery due to vortex formation. In addition, the curvature and tortuosity of arterial configurations can also produce swirl flows. The present study was performed to investigate fractional flow reserve alterations in a post-stenotic distal part due to the presence of pre-stenotic swirl flow by computational fluid dynamics analysis for virtual stenotic models by quantifying fractional flow reserve(FFR). Simplified stenotic coronary models were divided into those with and without pre-stenotic swirl flow. Various degrees of virtual stenosis were grouped into three grades: mild, moderate, and severe, with degree of stenosis of 0 ~ 40%, 50 ~ 60%, and 70 ~ 90%, respectively. In this study, three-dimensional computational hemodynamic simulations were performed under hyperemic conditions in virtual stenotic coronary models by coupling with a zero-dimensional lumped parameter model. The results showed that the influence of pre-stenotic swirl inflow is dominant on FFR alteration in mild stenosis, whereas stenosis is dominant on FFR alteration in moderate/severe stenosis. The decrease in FFR caused by swirl flow is more significant in mild stenosis than moderate/severe stenosis. Biomechanical modeling is useful for clinicians to provide insight for medical intervention strategies. This hemodynamic-based parameter study could play a critical role in the development of a non-invasive imaging-based strategy-support system for percutaneous transluminal angioplasty in cases of mild/moderate stenosis.

• 폴리머
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• 제30권6호
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• pp.568-571
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• 2006

Poly(vinyl alcohol) (PVA)/gelatin(GEL) 블렌드막을 고전장하에서 제조한 후, 팽윤거동 및 이온투과 특성을 연구하였다. 알칼리 금속염(LiCl, NaCl, KCl)에 대한 투과 실험 결과, 인가된 전장의 강도가 10 kV까지 증가하면 막의 곡로율이 감소하여 이온 투과도가 증가하지만, 10 kV이상이 되면 막의 결정화도의 증가 영향이 커져 투과도는 감소하였다. 완충용액에 대한 팽윤 실험에서 pH 6을 기점으로 산성영역 혹은 염기성 영역으로 갈수록 하전기간의 반발로 인하여 팽윤도가 증가함을 관찰하였다. 제조된 블렌드막의 KCl 투과도 계수는 pH 6에서 극대값을 보였고, 산성 혹은 염기성 영역으로 갈수록 급격히 감소되는 것을 확인하였다. 이러한 거동은 막내 존재하는 관능기들이 해리함에 따라 용해도 증가 영향보다는 Donnan 배제효과가 우세하게 작용하기 때문인 것으로 생각된다. 특히 온도에 따른 투과거동에서 $40^{\circ}C$를 기점으로 KCl 투과도 계수가 약 5배 정도 급격히 증가함을 보여주었다.

• 한국터널지하공간학회 논문집
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• 제16권4호
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• pp.417-430
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• 2014

도심지 내 지하공간의 효율적인 활용을 위해서 연마재 워터젯 시스템(abrasive waterjet system)을 이용한 새로운 형태의 암반굴착 공법이 개발되어 활용 중에 있다. 연마재 워터젯 시스템을 활용한 굴착(절삭) 수행 시 적정량의 연마재를 투입하고 연마재입자의 유동성을 원활하게 유지하는 것은 매우 중요하다. 본 연구에서는 실내실험을 통해 연마재 입자의 유동성과 관련된 영향인자들을 연마재 관 설치높이, 연마재 관 길이, 연마재 관 굴곡도 그리고 연마재 관 내경으로 나누어 연마재 투입량 및 유동성 수준을 평가하였다. 또한, 실험결과를 바탕으로 연마재 투입량 및 연마재 입자 유동성에 관한 최적 조건을 제시하였다. 본 연구결과를 바탕으로 향후 암반 굴착용 워터젯 공법이 도심지 내 터널, 공동구, 수직구 건설 등 다양한 지반 구조물 굴착 작업 시, 최적 연마재 투입을 위한 기초자료로 유용하게 활용될 수 있을 것으로 기대된다.

• Journal of Korean Neurosurgical Society
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• 제64권1호
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• pp.60-68
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• 2021

Objective : Until recently, the transfemoral approach (TFA) was used as the primary method of arterial approach in acute ischemic stroke (AIS). However, TFA resulted in longer reperfusion times and worse outcomes in the mechanical thrombectomy (MT) of patients with complex aortic arches and significant carotid tortuosity. We found that the transradial approach (TRA) is a more favorable alternative approach for MT in such cases. Methods : We performed a retrospective review of our institutional database to identify 202 patients who underwent MT for AIS between February 2015 and December 2019. Patient characteristics, cause of TFA failure, procedure time, intra-procedural complications, and outcomes were recorded. Results : Eleven (5.4%) of 202 patients, who underwent MT for AIS, crossed over to TRA for recanalization, and eight (72%) of 11 achieved successful recanalization (≥modified Treatment in Cerebral Infarction 2b). The mean age (mean±standard deviation [median]) was 82.3±6.6 (76) years, and five of the 11 patients were male. The last seen normal to puncture time was 467.9±264.72 (264) minutes; baseline National Institutes of Health Stroke Scale score was 28.9±14.5 (16). Six (55%) of the 11 patients had right vertebrobasilar occlusions, and the remaining five (45%) had anterior circulation occlusive disease. The time from groin puncture to final recanalization time (overall procedural time) was 78.0±20.1 (62) minutes. The mean crossover time from TFA to TRA was 45.2±10.5 (41) minutes. The mean time from radial puncture to final recanalization was 33.8±10.5 (28) minutes. Distal thrombus migration events in previously unaffected territories occurred in 3/8 patients (37%). At 90 days, three patients (28%) had a favorable clinical outcome. Conclusion : Although rare, failure of TFA has been known to occur during MT for AIS. Our results demonstrate that TRA may be an alternative option for AIS intervention for select patients with subsequent timely revascularization. However, the incidence of distal thrombus migration was high, and the first puncture to reperfusion time was prolonged because of the time taken for the crossover to TRA after failure of TFA. This study provides some evidence that the TRA may be a viable alternative option to the TFA for MT of AIS.

• Anatomy and Cell Biology
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• 제56권3호
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• pp.360-366
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• 2023

Increased tortuosity of vessel is associated with high incidence of plaque formation leading to atherosclerosis. Surgical procedures are done after analyzing morphology of middle cerebral artery (MCA). However, literature describing MCA morphology using computed tomography angiography (CTA) is limited, so this study was planned to determine its incidence in Indian population. Datasets of CTA from 289 patients (180 males and 109 females), average age: 49.29±16.16 years (range: 11 to 85 years), from a tertiary care hospital were systematically reviewed for morphology of MCA. Cases involving aneurysms and infarcts were excluded. Four shapes of MCA were recognized: straight, U, inverted U, and S-shaped. MCA was straight in 44% (254/578), U-shaped in 37% (215/578), S shaped in 15% (89/578) and inverted U-shaped in 3% (20/578) cases. In males, MCA was straight in 46% (166/360), U-shaped in 37% (134/360), S-shaped in 16% (58/360) and inverted U-shaped in 4% (14/360) cases. In females, MCA was straight in 42% cases (92/218), U-shaped in 37% (81/218), S-shaped in 17% (36/218) and inverted U-shaped in 4% (9/218). On comparing shape with various age groups using chi square test, U shaped (P≤0.001) and S-shaped (P=0.003) MCA were found to be statistically significant. The incidence of straight shape was higher in advanced age group (>60 years). Knowledge of MCA shape will be useful for clinicians and surgeons in successful endovascular recanalization. Also, this data would help surgeons during neurointerventional procedures.