• The Journal of the Acoustical Society of Korea
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• v.14 no.2E
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• pp.73-86
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• 1995

The transducer section of the forward-looking ultrasound imaging catheter (FLUIC) consists of a circular piezoelectric element as a vibrator and a conical acoustic mirror as a perfect reflector. A small diameter piezoelectric transducer element is mounted on the side of a catheter's rotating shaft. The unique design of FLUIC provides the capability to form a two-dimensional image of a cross-section of vessel in front of the catheter, which is lacking in the present generation of intravascular ultrasound (IVUS) transducers, as well as a conventional side view image. The mirror configuration for the transducer section of the FLUIC is designed using an approximated ray tracing techniques. The diffraction transfer function approach [1] developed for the field prediction from primary sources is generalized and extended to predict the secondary diffraction characterstics from an acoustic mirror. The extended model is verified by simulation and experiment through a simple plane reflector and employed to analyzed the field characteristics of a FLUIC.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.40 no.10
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• pp.879-886
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• 2016

Tractrix dies, used in the deep drawing process, can be used to form CNG pressure vessels without a blank holder. Previous studies had only applied tractrix profiles to perform the first deep drawing process of DDI; but an optimal design of the tractrix die that focuses on improving die life and reducing production cost has not been performed yet. In this study, finite element analyses of deep drawing processes were conducted according to heights of the tractrix die by using translating asymptotes. In addition, researchers analyzed von-Mises stresses at the part of stress concentration of the die according to the forming punch loads in order to propose an optimal tractrix die design.

• Composites Research
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• v.34 no.6
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• pp.350-356
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• 2021

When a ship with a planing line operates or turns in a straight line, the floating position and trim change according to the speed, and a large resistance is generated on the hull. In this paper, the resistance to a planing line was estimated through the computational fluid dynamics of a leisure boat with improved hull weight and durability by applying a carbon composite material to the hull. The resistance performance of the bow and stern of the 18ft class leisure boat was checked and the flow field of the entire vessel was estimated, and the stability of the planing line was confirmed by comparing the resistance of each trim through numerical analysis. In addition, it was confirmed that the designed planing line could withstand it sufficiently because the force applied to the hull was not large, and The stability of the boat was analyzed by calculating the wavelength of the wave and the length of the ship as the ratio of gravity to the inertial force and checking how much force the rolling occurred.

• Journal of Korean Neurosurgical Society
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• v.44 no.4
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• pp.190-195
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• 2008

Objective : There have been numerous follow-up studies of patients who had ruptured or unruptured intracranial aneurysms treated by wrapping technique using various materials have been reported. Our objective was to ascertain whether our particular wrapping technique using the temporalis muscle provides protection from rebleeding and any aneurysm configuration changes in follow-up studies. Methods : Clinical presentation, the location and shape of the aneurysm, outcomes at discharge and last follow-up, and any aneurysm configuration changes on last angiographic study were analyzed retrospectively in 21 patients. Reinforcement was acquired by clipping the wrapped temporalis muscle. Wrapping and clipping after incomplete clipping was also done. Follow-up loss and non-angiographic follow-up patient groups were excluded in this study. Results : The mean age was 53 years (range 29-67), and 15 patients were female. Among 21 patients, 10 patients had ruptured aneurysms (48%). Aneurysms in 21 patients were located in the anterior circulation. Aneurysm shapes were broad neck form (14 cases), fusiform (1 case), and bleb to adjacent vessel (6 cases). Five patients were treated by clipping the wrapped temporalis, and 16 patients by wrapping after partial clipping. The mean Glasgow coma scale (GCS) at admission was 14.2. The mean Glasgow outcome scale (GOS) at discharge was 4.8, and 18 patients were grade 5. The mean period between initial angiography and last angiography was 18.5 months (range 8-44). Aneurysm size was not increased in any of these patients and configuration also did not change. There was no evidence of rebleeding in any of these treated aneurysms. Conclusion : Our study results show that wrapping technique, using the temporalis muscle and aneurysm clip(s), for intracranial aneurysm treatment provides protection from rebleeding or regrowth.

• Journal of Navigation and Port Research
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• v.34 no.6
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• pp.447-452
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• 2010

A very good seakeeping vessel is able to operate effectively even in high sea states and also the passengers and the cargos are ensured in good conditions. The motions of a high speed boats are highly influenced by speed and dynamic forces even in encounter frequencies so that the assessment of seakeeping ability of the design craft in an early stage needs to be calculated for all three motions and for all ralative wave headings. In this paper, it concludes that RAO and RMS values of the catamaran's 3 motion are calculated according as the variation of Beafort scales and ship's speed. The ship motion response of the catamaran based on the RAO and RMS by encounter angles and speed was calculated.

• Journal of Chest Surgery
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• v.22 no.2
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• pp.308-314
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• 1989

Pulmonary sequestration is a congenital malformation characterized by an area of embryonic lung tissue that derives its blood supply from an anomalous systemic artery. Two forms recognized: extralobar and intralobar. Extralobar form is a very rare congenital malformation, usually located in the lower chest, and may be found in newborn infants at the time a congenital diaphragmatic hernia is repaired. Large sequestrated segments may be cause acute respiratory distress in the neonate. The condition is asymptomatic in 15 per cent of patients. This report presents two cases of pulmonary sequestration which misdiagnosed a superior mediastinal tumor and a benign lung tumor. First case was 30-year-old male patient and chief complaints were dyspnea, dry cough and right chest pain. Chest X-ray showed a homogenous increased density of smooth margin at the right superior mediastinal area and suggested a benign mediastinal tumor. And so explothoracotomy was made without other special studies. Second case was 28-year-old male patient. One month ago, he had tracheostomy and right closed thoracostomy due to massive hemoptysis and spontaneous hemothorax. Chest X-ray showed a benign cystic lesion at RLL area. At the time of operation, in first case, a mass of adult fist size was placed medial to the right upper lobe and densely adhesive to trachea, SVC and esophagus. Blood supply of the mass was bronchial arteries of trachea and RUL bronchus and drained to SVC and azygos vein through anomalous systemic veins. There was no bronchial communication on Frozen biopsy. In 2nd case, large cystic lesion contained old blood hematoma was located in RLL and anomalous blood vessel from thoracic aorta was drained to posterior segment of RLL. In operation field, intralobar pulmonary sequestration was diagnosed, and RLL lobectomy was carried out.

• Journal of Biomedical Engineering Research
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• v.19 no.5
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• pp.449-454
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• 1998

It is well known that new tissue or blood vessel is grown into a porous calcium phosphate ceramics used as a bone graft substitute due to their excellent biocompatibility. In this study, the most chemically stable porous $\beta$-crystalline form in various forms of calcium metaphosphate, Ca(PO$_3$)$_2$is prepared by the controlled thermolysis of monocalcium phosphate, Ca(H$_2$PO$_4$)$_2$.The diameter of cylindrical pores formed during cooling was controlled by a holding time at the melting point of a monocalcium phosphate and by the change of a crystallization temperature, to obtain the most appropriate size (about 200$\mu$m) of pores for the application of bone substitutes and matricuts. It was observed that the increasing holding time at the melting point of monocalcium phosphate results in the decreases of cylindrical pore sizes.

• Journal of the Korean Institute of Gas
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• v.25 no.3
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• pp.16-26
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• 2021

The global warming problem has arose, the supply eco-friendly vehicles such as HFCEVs is increasing around world and Korea is fully supporting subsidies, tax cut to form an initial market for HFCEVs. The key to the safety of HFCEVs is pressure vessels stored hydrogen, and although these pressure vessels must be inspection regularly, the existing inspection stations are insufficient to meet the demand for inspection. Therefore, it is important to establishment of pressure vessels inspection station for safety management of HFCEVs. In this study, it estimates innovation coefficient, imitation coefficient in Bass model by using electric vehicle sales data, and foretasted the supply of HFCEVs by region & the demand for inspection by region using the Bass diffusion model. As a result, the inspection demand for pressure vessels in HFCEVs in 2040 was 690,759 units, and it was confirmed 191 new inspection stations and 1,124 inspectors were needed to prepare for this.

• Journal of the Korean Society of Marine Environment & Safety
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• v.17 no.4
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• pp.429-434
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• 2011

Bulk cargo loaded into ship can be damaged by various kinds reasons. This paper aims to analyze about cargo damage of coil carrier ship due to condensation. Condensation is the formation of liquid drops of water from water vapor. Condensation consists of small drops of water which form when warm water vapour or steam touches a cold surface such as a window. In general, condensation have occurred by temperature difference at large building and ship's tank. It is phenomenon that can occur often to oceangoing vessel moving temperature difference places in similar time. This paper proposes a new method using dehumidification device and fan heater to prevent bulk cargo damage of coil carrier ship from condensation.

• Fire Science and Engineering
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• v.20 no.3 s.63
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• pp.29-34
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• 2006

The flash and fire point are the most important combustible properties used to determine the potential for the fire and explosion hazards of flammable material. The flash point is defined as the lowest temperature at which a flammable liquid gives off sufficient vapor to form an ignitable mixture with air near its surface or within a vessel. The fire point is the temperature of the flammable liquid at which there will be flaming combustion, sustained 5 seconds in response to the pilot flame. In this study, the flash points and fire points were measured to present raw data of the flammable risk assessment for acids, using Pensky-Martens Closed Cup(C.C.) apparatus (ASTM-D93) and Tag Open-cup (O.C.) apparatus(ASTM D 1310-86). The measured fire points were compared with the estimated values based on 1.11 times stoichiometric concentration. The values calculated by the proposed equation were in good agreement with measured values.