• 한국가시화정보학회:학술대회논문집
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• 2004.12a
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• pp.135-140
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• 2004

Several studies have utilized physical models of the healthy nasal cavity to investigate the relationship between nasal anatomy and airflow. With our experiences of experimental investigations on nasal airflows in normal and abnormal nasal cavity models, we are going to deal with the topic that may contribute to the diagnosis and treatment of nasal diseases. In this paper, airflows in the normal and artificially deformed models, which simulate surgical treatment, are investigated experimentally by PIV. High-resolution CT data and careful surface rendering of computational model with the help of the ENT doctor provide more sophisticated nasal cavity models. The CBC PIV (Correlation Based Correction PIV) algorithm with window offset is used for PIV flow analysis. Average and RMS distributions in sagittal and coronal sections are obtained for inspiratory and expiratory nasal airflows. Comparisons in nasal airflows for both normal and deformed cases are also appreciated. In case of simulations of surgical operations, velocity and RMS distributions in coronal section changes locally, this may cause some difficulties in physiologic functions of noses and may hurt mucosal surface.

• International Journal of Aeronautical and Space Sciences
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• v.9 no.2
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• pp.87-97
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• 2008

Modem anti-ship missiles employ complex and sophisticated guidance laws to hit the target and enhance their survivability by executing additional maneuvers. However, such maneuvers may cause the target to move out of the missile seeker's Field-Of-View (FOV). Maintaining seeker lock-on during an engagement is a critical factor for missile guidance. In this paper, a guidance law switching logic that maintains seeker lock-on and a simple guidance law that keeps the target look angle of the seeker constant is proposed. The proposed method can be used for the terminal homing phase, and can be switched from any kind of guidance laws if a proper switching condition is satisfied. The minimum and maximum flight time calculation method in consideration of the missile maneuver limit and the FOV of the seeker is also provided.

• Electronics and Telecommunications Trends
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• v.3 no.4
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• pp.3-12
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• 1988

Epilayer growing process has been recognized as a key technology for successful GaAs based devices and integrations. These may include HEMT, multiple quantum well structures, band gap engineering, and quantum confinement heterostructures. The fabrication of epilayers in these devices must meet very stringent requirements in terms of crystallinity, composition, film thickness and interface quality. In particular, the quality of interfaces is getting more important because the film thickness, and flatness, roughness and stability at interface of ultrathin films cause critical effects on the device performance. This article reviews the current status of modern epitaxial techniques which have been developed in the last few years. First, the new techniques PLE, GI, MEE, TSL based on MBE technique will be reviewed and their technical importance will be stressed. Secondly, MOMBE, GSMBE, CBE which combine the advantages of MBE and MOCVD will also be discussed. Thirdly, the new sophisticated epitaxial technique, ALE, of which mechanism is totally different from others, will also be reviewed. Finally, areas which should be exploited more extensively to accomplish these techniques will be addressed.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• v.44 no.4
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• pp.151-158
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• 2018

Zygomatic fractures are the second most common fractures of the facial skeleton, after nasal bone fractures. Due to its uniqueness, the malar bone plays a very important role in maintaining appropriate facial contours. Zygomatic fractures can cause ocular and mandibular functional impairment, along with cosmetic defects. With the help of advanced imaging techniques and various treatment options, the management of zygomatic fractures has become more sophisticated and less invasive. This article discusses zygomatic fractures in detail: their clinical and radiographic features, and the various treatment options available.

• Computers and Concrete
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• v.24 no.3
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• pp.271-282
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• 2019

Concrete undergoes a series of thermo-based physio-chemical changes once exposed to elevated temperatures. Such changes adversely alter the composition of concrete and oftentimes lead to fire-induced explosive spalling. Spalling is a multidimensional, complex and most of all sophisticated phenomenon with the potential to cause significant damage to fire-exposed concrete structures. Despite past and recent research efforts, we continue to be short of a systematic methodology that is able of accurately assessing the tendency of concrete to spall under fire conditions. In order to bridge this knowledge gap, this study explores integrating novel artificial intelligence (AI) techniques; namely, artificial neural network (ANN), adaptive neuro-fuzzy inference system (ANFIS) and genetic algorithm (GA), together with traditional statistical analysis (multilinear regression (MLR)), to arrive at state-of-the-art procedures to predict occurrence of fire-induced spalling. Through a comprehensive datadriven examination of actual fire tests, this study demonstrates that AI techniques provide attractive tools capable of predicting fire-induced spalling phenomenon with high precision.

• Journal of the Society of Naval Architects of Korea
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• v.47 no.3
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• pp.306-320
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• 2010

Modern ultra-large container carriers can be exposed to the unprecedented springing excitation from ocean waves due to their relatively low torsional rigidity. Large deck opening on the deck of container carriers tends to cause warping distortion of hull structure under wave-induced excitation, eventually leading to the higher chance of resonance vibration between its torsional response and incoming waves. To handle this problem, a higher-order B-spline Rankine panel method and Vlasov-beam FE model was directly coupled in the time domain, and the coupled equation was solved by using an implicit iterative method. In order to capture the complicated behavior of thin-walled open section girder, a sophisticated beam-based finite element model was developed, which takes into account warping distortion and shear-on-wall effect. Then, the developed beam model was directly coupled with the time-domain Rankine panel method for hydrodynamic problem by using the fixed-point iteration method. The developed computational scheme was validated through the comparison with the frequency-domain solution on the container carrier model in linear springing regime.

• Journal of Advanced Marine Engineering and Technology
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• v.33 no.1
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• pp.112-119
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• 2009

The mechanical fastening has some advantages in respect of the fastening strength and disassemble of the fastened parts. However, at the same time it has some dangerous factors, can cause fatigue crack initiation and propagation due to not only the static loading such as cargo and passengers but also the dynamic loading like vibrations which occur in the engines and the propellers. For this reason, the strength evaluation for the mechanical fastenings along with the sophisticated and detailed mechanical design and the safety evaluation should be executed, In this paper, we were carried out experiments to study fatigue crack growth paths in structures containing the multiple circular holes. It was investigated that how circular holes are affected on fatigue crack growth paths using the specimen consists of A5052-H112, which is widely used as the ship materials. It was found from the experimental results that the fatigue crack as if it is drawn to circular holes when crack tip approach to circular holes. However, it did not go into circular hole if there is the next circular hole. Therefore, the clarification of mechanism on the fatigue crack initiation and the propagation in structures containing the multiple circular holes can be expected in this study.

• Fire Science and Engineering
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• v.22 no.5
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• pp.125-136
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• 2008

Corruption of the bureaucratic society can cause the whole society to corrupt and it can also increase public expense gradually because of the civil society's distrust of the administration. Throughout experience of front-line firefighters, this study lets the entire firefighters take an interest in increasing integrity and make it the primary assignment of fire administration. It is the most important to find out the illogical systems and try to improve them in order to solve the increasingly secret and sophisticated forms of corruption completely. The purpose of this study is to show the ways to improve firefighters' integrity by analyzing and pointing out the main factor and the realities of corruption of firefighters.

• Journal of the Korean Society of Visualization
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• v.9 no.3
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• pp.65-70
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• 2011

Three major physiological functions of nose can be described as air-conditioning, filtering and smelling. Detailed knowledge of airflow characteristics in nasal cavities is essential to understanding of the physiological and pathological aspects of nasal breathing. In our laboratory, a series of experimental investigations have been conducted on the airflows in normal and abnormal nasal cavity models by means of PIV under both constant and periodic flow conditions. In this work, more specifically experimental and numerical results on the surgically modified inferior turbinate model were presented. With the high resolution CT data and a careful treatment of the model surface under the ENT doctor's advice yielded quite sophisticated cavity models for the PIV experiment. Physiological nature of the airflow was discussed in terms of velocity distribution and vortical structure for constant inspirational flow. Since the inferior and middle turbinate are key determinants of nasal airflow, the turbinectomy obviously altered the main stream direction. This phenomenon may cause local changes in physiological function and the flow resistance.

• The Korean Journal of Pain
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• v.1 no.2
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• pp.199-202
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• 1988

Secure fixation is essential for continous epidural catheterization on a long-term-basis. Adhesive tape or surgical knots were commonly used for those patients, but the surgical knot method has a tendency to cause strangulation of catheter. Another invasive technique, subcutaneous tissue tunnelling is more safe than other methods but requires sophisticated technique and time. We employed a simple device using a blood transfusion set for patients who have epidural catheters placed safely un their backs. In 120 patients treated for postoperative and chronic pain by means of this technique, the results were as follows: 1) Five of 120 patients (4.2%) developed backache and pruritus, but there were no instances of respiratory depression, local infection and headache. 2) Nine of 120 patients (7.5%) failed booster-injections, but two cases were due to be non-technical errors. 3) The duration of fixation was 1~3 days in most cases (85%), the longest being for 21 days.