• Journal of the Korean Society for Nondestructive Testing
• /
• v.19 no.5
• /
• pp.347-355
• /
• 1999

A feasibility investigation on vibration-based nondestructive evaluation of thermal stress-induced micro-failure in the free edge region of thin composite laminates(1mm thick) has been carried out. The failure occurrence and damage zone, which were predicted by the three-dimensional finite-element thermal stress analysis, were observed using the ultrasonic C-scan and optical microscopy. Analysis of the vibration spectrum measured from the laminate beam specimens by the vibration sweep test exhibited that the obvious decrease in resonancy frequency and some considerable increase in damping factor were associated with the micro-failure formation. The vibration technique utilizing short beam and high resonant frequency was found to be very sensitive to the thermal stress-induced damage in the thin laminates.

• The Journal of The Korea Institute of Intelligent Transport Systems
• /
• v.10 no.3
• /
• pp.16-24
• /
• 2011

The vehicle electronic control system is being developed as the legal and social demand for ensuring driver's safety is rising. The various Driver Assistance Systems with various sensors such as radars, camera, and lasers are in practical use because of the falling price of hardware and the high performance of sensor and processer. In the preceding study of this research, the program was developed to recognize the experiment vehicle's driving lane and the cars nearby or approaching the experiment vehicle throughout the images taken by CCD camera. In addition, the 'dangerous driving analysis program' which is Vision System basis was developed to analyze the cause and consequence of dangerous driving. However, the Vision system developed in the previous studyhad poor recognition rate of lane and vehicles at the time of passing a tunnel, sunrise, or sunset. Therefore, through mounting the brightness response algorithm to the Vision System, the present study is aimed to analyze the causes of driver's dangerous driving clearly by improving the recognition rate of lane and vehicle, regardless of when and where it is.

• 한국태양에너지학회:학술대회논문집
• /
• 2012.03a
• /
• pp.211-216
• /
• 2012

Proton Exchange Membrane Fuel Cells (PEMFC) are the most appropriate for energy source of small robot applications. PEMFC has superior in power density and thermodynamic efficiency as compared with the Direct Methaol Fuel Cell (DMFC). Furthermore, PEMFC has lighter weight and smaller size than DMFC which are very important factors as small robot power system. The most significant factor of mobile robots is weight which relates closely with energy consumption and robot operation. This research tried to find optimum specifications in terms of type, number of cell, active area, cooling method, weight, and size. In order to find optimum 500W PEMFC, six options are designed in this paper and studied to reduce total stack weight by applying new materials and design innovations. However, still remaining problems are thermal management, robot space for energy sources, and so on. For a thermal management, design options need to analysis of Computational Fluid Dynamics (CFD) for determining which option has the improved performance and durability.

• Proceedings of the KSR Conference
• /
• 2007.11a
• /
• pp.1610-1615
• /
• 2007

This paper presents a characteristics of linear induction motor considering airgap variation for railway transit in order to achieve high performance of the vehicle. The operating principle of a LIM(Linear induction motor) is identical to a rotary induction motor. Space-time variant magnetic fields are generated by the primary part across the airgap and induce the electro-motive force(EMF) in the secondary part, a conducting sheet. This EMF generates the eddy currents, which interact with the airgap flux and so produce the thrust force known as Loren's force. Even though the operating principal is exactly same as a rotary motor, the linear motor has a finite length of the primary or secondary parts and it causes static and dynamic end-effect which is the discontinuous airgap flux phenomenon. This end-effect causes the deterioration of the system performance, especially in high-speed operation. Another problem is that construction tolerance restricts the minimum airgap in order to prevent a collision between the primary part and the secondary reaction plate. More over, as the airgap length is getting smaller, the attraction force between the primary part and secondary parts is getting larger dramatically and the attraction force would be another friction against propulsion. Therefore, it is necessary to figure out the characteristics of linear induction motor considering airgap variation in order to achieve high performance of the vehicle. The dynamic model of LIM taking into account end-effects is derived. Then the modified mechanical load equation considering the effect of the attraction and thrust force according to the airgap variation is analyzed. The simulation results are presented to show the effect of the LIM according to the airgap variation.

• Journal of Fisheries and Marine Sciences Education
• /
• v.26 no.4
• /
• pp.789-796
• /
• 2014

This study was conducted to investigate the effects of feeding rate on growth performance, blood components and histology of growing olive flounder. The experiment was carried out to determine the optimum feeding rate of the fish (initial fish mean weight of $97{\pm}3.0$ g) at the optimum water temperature. Two replicated groups of fish were fed commercial diet at the feeding rates of 0, 1.0, 1.65 and 2.3% body weight (BW)/day and satiation. Feeding trial was conducted under a flow-through system with ten 1.2 metric ton aquaria receiving filtered seawater at $21{\pm}2^{\circ}C$ for three weeks. Weight gain and specific growth rate (SGR) for fish fed to satiation were significantly higher than those for the unfed fish and for fish fed at 1.0 and 1.65% BW/day. There were no significant differences in values of such parameters between fish fed at 1.65% and those fed at 2.3% BW/day and between fish fed at 2.3% and those fed to satiation. Weight gain and SGR for the unfed fish were significantly lower than those for fish in the other treatments. All the tissues (hepatopancreas, kidney and anterior intestine) were in good condition in fish fed the experimental diet at different feeding rates. This result indicates that the optimum feeding rates of olive flounder (97-160 g) was approximately 2.52% BW/day at the optimum water temperature.

• Journal of Korean Society of Coastal and Ocean Engineers
• /
• v.31 no.6
• /
• pp.356-367
• /
• 2019

This study evaluates the variation characteristics of irregular wave fields for two-dimensional Low-Crested Structure (LCS) by olaFlow model based on the two-phases flow by numerical analysis. The numerical results of olaFlow model are verified by comparing irregular wave profile of target wave spectrum and measured one, and their spectra. In addition, spacial variation of irregular wave spectrum, wave transmission ratio, root-mean square wave height, time-averaged velocity and time-averaged turbulent kinetic energy by two-dimensional LCS are discussed numerically. The time-averaged velocity, one of the most important numerical results is formed counterclockwise circulating cell and clockwise nearshore current on the front of LCS, and strong uni-directional flow directing onshore side around still water level.

• Biomolecules & Therapeutics
• /
• v.14 no.3
• /
• pp.166-170
• /
• 2006

In this study, we investigated whether schizandrin, schizandrin-A, gomisin-A and uridine affect mucin secretion from cultured airway epithelial cells and compared the potential activities of these agents with the inhibitory action on mucin secretion by poly-1-lysine (PLL) and the stimulatory action by adenosine triphosphate (ATP). Confluent primary hamster tracheal surface epithelial (HTSE) cells were metabolically radiolabeled using $^3H-glucosamine$ for 24 h and chased for 30 min in the presence of varying concentrations of each agent to assess the effects on $^3H-mucin$ secretion. The results were as follows: schizandrin-A and uridine increased mucin secretion at the highest concentrations ($2{\times}10^{-4}\;-\;10^{-3}M$). We conclude that schizandrin-A and uridine can stimulate mucin secretion via direct effect on airway mucin-secreting cells and suggest that these agents be further investigated for the potential use as mucoregulators during the treatment of chronic airway diseases.

• Korean Journal of Veterinary Research
• /
• v.38 no.3
• /
• pp.497-507
• /
• 1998

The localizations and morphological characteristics of immunoreactive cells for prolactin(PRL) and growth hormone(GH) antisera were studied with double immunohistochemistry in the adenohypophysis of the Korean native goat. PRL immunoreactive cells(mammotropes) and GH immunoreactive cells(somatotropes) were present in the pars distalis and pars tuberalis, but not in the pars intermedia. A few cells were stained with both PRL and GH antisera (somatomammotropes). The possessional percentages of mammotropes, somatotropes and somatomammotropes were 37.0%, 32.6%, 1.0% in females and 35.6%, 32.6%, 1.1% in males, respectively. Mammotropes were oval or round in shape, and $10{\sim}20{\mu}m{\times}17{\sim}25{\mu}m$ in size. These cells were distributed throughout the pars distalis, but were more abundant on the dorsal part adjacent to the hypophyseal cavity and along the lateral and ventral peripheral regions. Somatotropes were elliptical, triangular or polygonal in shape, and $8{\sim}17{\mu}m{\times}17{\sim}18{\mu}m$ in size. The distribution pattern of somatotropes was similar to that of mammotropes. Some somatomammotropes were intercalated between clusters of mammotropes while the others were dispersed independently among the secretory cells.

• International Journal of Industrial Entomology and Biomaterials
• /
• v.4 no.2
• /
• pp.155-162
• /
• 2002

Cytochrome P45O (CYP) gene has been known to play one of the most important roles in metabolizing the exogenous materials. In insect, CYP is particularly known to detoxify toxic materials by adding oxygen molecule to the hydrophobic region of the materials. Thus, CYP-dependent metabolism is associated with the adaptation of insect to host plant chemicals. This in turn is known to be one of the driving forces for CYP diversification. In the present study, we cloned seven gene fragments of CYP 4 (CYP4) family from the midgut of the beet armyworm, Spodoptera exigua, through RT.PCT, Sequence analysis of the product showed the gene fragment to contain an open reading frame of ~150 amino acids, consisted of ~450 bp. The cloned gene fragments contained typical, conserved regions found in CYP4 family. Pairwise comparison of the deduced amino acid sequences among seven clones ranged in divergence from 0% to 52.86% and resulted in five distinct clones. The other two clones were identical or differ by one amino acid respectively to the corresponding clone, although each differed by ten nucleotides. Analysis of correlation between GenBank-registered, full length CYP4 and the cloned fragments resulted in statistically significant relationship ($r^{2}$ = 0.96085; p < 0.001), suggesting utility of the partial sequences as such full-length sequences. Phylogenetic analysis of the clones with GenBank-registered insect and mammal CYP4 family sequences by parsimony and several distance methods subdivided the clones into two groups: tones belonging to CYP4S and the others to CYP4M families.

• Archives of Craniofacial Surgery
• /
• v.20 no.6
• /
• pp.388-391
• /
• 2019

Schwannoma is a slow-growing, well-demarcated, benign soft tissue tumor of the peripheral nerve sheath. It commonly develops in the head and neck region, usually in the parapharyngeal space. In this case, a 42-year-old woman visited the outpatient department to manage a painless mass on her left cheek. She had no history of concern and no neurological symptoms were observed. In the enhanced computed tomography scan, a 2.8×2.8×1.8 cm, heterogeneously enhanced tumor was detected in the left masseter muscle. A tumor resection under general anesthesia was planned. For the resection, a facelift incision was chosen; branches of the facial nerve were identified and retrogradely dissected. A well-marginated, yellowish, solid mass was found in the left masseter muscle. The mass was excised and given a histopathological diagnosis of schwannoma. A definite diagnosis of schwannoma, originating in the masseter muscle, is difficult to arrive at with radiographic findings alone; it is often misdiagnosed as intramuscular hemangioma. Histopathological examinations, including fine-needle aspiration or histological biopsy after surgery, are necessary. Using a facelift incision with retrograde facial nerve dissection, tumor resection in an intramasseteric lesion can be performed efficiently, without nerve damage, or leaving conspicuous scars on the face.