• Bulletin of the Korean Chemical Society
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• v.35 no.8
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• pp.2423-2430
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• 2014

Nitrogen-doped short tubular carbons (N-STCs) with big inner diameter have been successfully synthesized via carbonization of polydopamine (PDA) wrapped halloysite nanotubes (HNTs). The obtained N-STCs have average length of $0.3{\mu}m$ with big inner diameter (50 nm), thin wall (2-3 nm) and large surface area ($776m^2g^{-1}$), and show excellent electrochemical properties. As an example in electrochemical applications, N-STCs were used to electrochemically detect hydrogen peroxide ($H_2O_2$) and glucose. The results showed that the N-STCs modified glassy carbon (N-STCs/GC) electrode had much better analytical performance (lower detection limit and wider linear range) compared to the acid-treated carbon nanotubes (AO-CNTs) based GC electrode. The unique structure endows N-STCs the enhanced electrochemical performance and promising applications in electrochemical sensing.

• Journal of the Korean Society of Visualization
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• v.10 no.2
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• pp.14-19
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• 2012

An optical fiber probe system for measuring the local void fraction in the air-water two-phase flow was developed with a 1550 nm light source. Air was injected through a nozzle placed in the center of the bottom wall of a water-filled cylindrical tank. The optical fiber probe having a diameter of $125{\mu}m$ was sufficiently thin to resolve the air-water interface of the bubbly flows. To verify the performance of the optical fiber probe, the synchronized high speed visualization study using a high speed camera was carried out. Comparison between the optical signals and the instantaneous bubble diffraction images confirms that the optical fiber probe is very accurate to measure the void fraction in two-phase flows. The estimated bubble diameter and the rising velocity by the optical fiber probe have 1% and 5% of accuracy, respectively.

• Journal of Veterinary Clinics
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• v.35 no.4
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• pp.146-149
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• 2018

A 7-year-old, castrated, male Maltese dog presented with hyporexia and depression for 3 days. Elevated serum amylase, lipase activities, and liver enzyme values were found upon blood examination. An abdominal mass was seen on radiographs caudal to the gastric body in the left middle abdomen. In the left middle abdomen, abdominal ultrasonography also revealed a massive, irregularly marginated, heterogeneous mass of unknown origin, and in the right cranial abdomen, heterogeneously hypoechoic pancreatic tissue and hyperechoic change of adjacent mesenteric fat were observed. Contrast-enhanced computed tomography showed an irregular contour of the left pancreatic limb as well as heterogeneously enhanced parenchyma. A low-attenuating peripancreatic fluid collection with a thin and irregular wall was also seen. Based on these findings, an atypical pancreatic abscess with necrotizing pancreatitis which manifested as walled-off necrosis was suspected. The mass was excised, and the pancreatic abscess was confirmed by histopathologic examination. No complications were found in the patient after two months of follow-up examination.

• Journal of Chest Surgery
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• v.7 no.1
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• pp.9-12
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• 1974

Bronchogenic cysts, though known as a relatively common malformation of the mediastinum, were rarely discussed in Korean literatures. Since the surgical removal of asymptomatic lesions was adopted as the reasonable therapeutic principle, the incidence of bronchogenic cysts were found to be higher than previously expected. Two cases of bronchogenic cysts operated on in The Dept. of Thoracic Surgery, Korea University Woo Sok Hospital were reported and related literatures were reviewed. Case 1. 5 year old boy with chief complaints of bulging cystic mass on left supraclavicular region during straining or coughing since his age of 2 was admitted, and cystogram with Lipiodol revealed hen-egg sized mass in the left antero-superior mediastinum without any communication with bronchus or esophagus. Cyst was successfully removed under general anesthesia thru left supraclavicular incision, and pathological examination of the cyst revealed thin cystic wall lined with stratified columnar epithelium and it`s content was milky white mucoid fluid devoid of any bacterial growth. Case 2. 15 year old school girl has been noted slowly growing walnut-sized mass on anterolateral side of the neck for 4 months without any subjective symptom except cosmetic problem... Mass was aspirated to find milky white mucoid fluid in some loculation and yellowish turbid fluid in other part due to chronic infection. Cystic tumor was removed under local anesthesia, which was loculated in between the trachea and esophagus without any communication, and pathological diagnosis of the cyst was bronchogenic cyst with columnar epithelial cell lining with moderate chronic inflammatory cell infiltrations. Postoperative conditions of the two cases were all excellent with normal life.

• Structural Engineering and Mechanics
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• v.46 no.5
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• pp.735-753
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• 2013

The wind load is always the dominant load of cooling tower due to its large size, complex geometry and thin-wall structure. At present, when computing the wind-induced response of the large-scale cooling tower, the wind pressure distribution is obtained based on code regulations, wind tunnel test or computational fluid dynamic (CFD) analysis, and then is imposed on the tower structure. However, such method fails to consider the change of the wind load with the deformation of cooling tower, which may result in error of the wind load. In this paper, the analysis of the large cooling tower based on the iterative method for wind pressure is studied, in which the advantages of CFD and finite element method (FEM) are combined in order to improve the accuracy. The comparative study of the results obtained from the code regulations and iterative method is conducted. The results show that with the increase of the mean wind speed, the difference between the methods becomes bigger. On the other hand, based on the design of experiment (DOE), an approximate model is built for the optimal design of the large-scale cooling tower by a two-level optimization strategy, which makes use of code-based design method and the proposed iterative method. The results of the numerical example demonstrate the feasibility and efficiency of the proposed method.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.25 no.2
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• pp.156-163
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• 2001

The experiment is conducted on the rapidly rotating incompressible flow within a confined cylinder using LDV(Laser Doppler Velocimetry). The configurations of interest are the flows between a rotating upper disk with a bar and a stationary lower disk enclosed within a cylinder. The flow is considered to be an axisymmetric undisturbed basic flow. The results show that the flow is strongly dependent on the radius and the shape of bar but is negligibly affected by the Reynolds number in turbulent flow. It is observed that in the lid-driven case the main forms near the wall as the Reynolds number increases. The thin bar causes the second axial flow due to the suction effect and the thick bar causes the main flow to be pulled toward the surface of the bar. The step bar shows the dual effect of the two. 1:2 tilt bar shows that the main flow distributes wider than the other cases in which interference occurs due step bar.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.25 no.7
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• pp.1131-1138
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• 2001

This paper concerns the crashworthiness of the widely used vehicle structure, the spot welded hat and double hat shaped section members, which are excellent on the point of the energy absorbing capacity and low production cost. The target of this paper is to analyze the energy absorption capacity of the structure against the front-end collision, and to obtain useful information for designing stage. Changing the spot weld pitches on the flanges, the hat and double hat shaped section members were tested on the axial collapse loads in impact velocities of 4.72m/sec, 6.54m/sec, 7.19m/sec and 7.27m/sec. To efficiently review the collapse characteristics of these sections, the simulation have been carried out using explicit FEM package, LS-DYNA3D. The solutions are compared with results from the impact collapse experiments.

• Proceedings of the Materials Research Society of Korea Conference
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• 2010.05a
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• pp.55.1-55.1
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• 2010

차세대 디스플레이용 전극 재료는 투명하면서도 낮은 저항값을 가져야 하는 투명 전극 재료로 금속, 금속산화물, 전도성 고분자, 탄소재료 등을 들 수 있다. 금속재료는 전도도는 우수하지만, 낮은 투과도로 투명전극 재료로 적절하지 않고, 대표적인 금속산화물 재료인 indium tin oxide (ITO)의 경우, 우수한 투과성과 낮은 면저항을 기반으로 차세대 디스플레이용 전극으로 현재 사용되고 있다. 하지만 ITO 박막은 휘거나 접을 때 기계적 안정성이 취약한 문제점을 나타내고 있다. 이러한 문제점을 극복하기 위해 전도성과 탄성계수가 높고, 저온에서 대면적 공정이 가능한 CNT을 투명 박막 전극 연구가 활발히 진행되고 있다. 하지만 투명전극 제조시, 탄소 나노튜브 간의 van der waals 인력에 의한 응집 현상으로 인한 분산의 불안정성과 분산제 사용으로 인하여 탄소 나노튜브 박막전극의 전기적, 광학적 특성이 저하를 야기한다. 이에 본 실험에서는 아크 방전 공정으로 합성한 SWCNT 분산액을 사용하여 spray coating 방법으로 glass 위에 박막을 형성하였다. SWCNT 투명 박막 전극 위에 DC sputtering을 이용하여 얇은Ni를 도포한 후, $450{\sim}500^{\circ}C$, ethylene gas 분위기의 thermal CVD방법으로 Carbon NanoFibers (CNFs)를 생성시킴과 동시에 분산제를 burning out하였다. CNF 성장 전후의 투명 박막의 전기적 특성은 four point probe를 이용하여 면저항과 UV-vis 장비를 이용하여 가시광선 영역에서의 광학적 투과도를 측정 비교하였다.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.28 no.1
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• pp.94-99
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• 1983

This experiment was conducted to study a cause of lodging on culm internode. The rice varieties were undergone on injuries by typo on 'Agnes' on Jeonbug Provincial in 1981 year. Long-culmed varieties had extreme lodging injury but short-culmed varieties were not serious. The lodging had weaken tolerance when culm internode was long, weight of internode per unit length was light, and culm diameter and culm wall were thin. The breaking weight of internode was light in lodging rice field. The internode length and the weight of internode per unit length between the breaking weight of internode had significant correlation. Lodging had high tolerance when the total nitrogen was low, phosphate, silica, cellulose and starch contents were high in internode. The difference of culm length and the weight of internode per unit length was high relationship with lodging.h lodging.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.28 no.1
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• pp.100-106
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• 1983

This experiment was conducted to study a cause of lodging on culm internode. The rice varieties were undergone on injuries by typo on 'Agnes' on Jeonbug Provincial in 1981 year. Long-culmed varieties had extreme lodging injury but short-culmed varieties were not serious. The lodging had weaken tolerance when culm internode was long, weight of internode per unit length was light, and culm diameter and culm wall were thin. The breaking weight of internode was light in lodging rice field. The internode length and the weight of internode per unit length between the breaking weight of internode had significant correlation. Lodging had high tolerance when the total nitrogen was low, phosphate, silica, cellulose and starch contents were high in internode. The difference of culm length and the weight of internode per unit length was high relationship with lodging.