• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.31 no.9
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• pp.1-8
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• 2003

Velocity data were acquired at a series of stations in the chordwise direction above a delta wing with leading edge extension, using a triple axis hot film anemometry. Surveys normal to planform yield velocity field data at incidence angle of 24$^{\circ}$and 32$^{\circ}$at a centerline chord Reynolds number of $1.76{\times}10^6$. Experimental results of velocity measurements of mean velocity of three components gave a confidence to quantitative investigate the vortical flow field over a LEX-delta wing with this probe. The present experiments indicated the existence of both wing and LEX vortex where the local mean axial velocity is maximum. It also shown the development of secondary vortex of opposite sign of rotating above the wing surface near the leading edge. The insertion of probe across the flow field was found to have little influence on the position of the vortex core.

• Journal of Korean Ophthalmic Optics Society
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• v.13 no.1
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• pp.49-52
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• 2008

To study the optical transmittance through nickel thin films with various thicknesses. Methods: We measured the optical transmittance through thin nickel film with various thicknesses. Results: The thickness dependence of the optical transmittance through nickel thin films deposited by thermal evaporation had been investigated. The optical transmittance rapidly decreased with the Ni film thickness less than 70 nm while it slightly decreased with the thickness more than 70 nm. In the experiment of optical dispersion, most of the light transmitted in the incidence direction. The result of experiment showed that optical dispersion was negligibly. Conclusions: Optical transmittance exponentially decreased as nickel thin film thickness increased.

• Journal of Korean Neurosurgical Society
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• v.37 no.6
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• pp.405-409
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• 2005

Objective: The purpose of this study is to assess the factors related to the outcome of 84 patients who underwent surgery for anterior communicating Artery(ACoA) aneurysms. Methods: The authors review 84 patients who were undertaken from January 1998 to May 2004. In the management of ACoA aneurysms, the outcome was based on several factors: Clinical condition, Distribution of hemorrhage, Time between aneurysmal rupture and surgery, Direction and shape of the aneurysm. Results: The incidence rate of the ACoA aneurysm was 35%. Seventy four patients were classified as those having a good recovery, but 5 patients suffered from some morbidity and 5 patients died. The rate of good outcome for the patients with Hunt and Hess grade was as follows 100% in grade I, 95% in grade II, 80% in grade III, IV and V. The rate of good outcome for the patients with Fisher grade was as follows 98% in grade I, II and 81% in grade III, IV. Nineteen of 22 patients who underwent early surgery were rated as good, while twenty six of 30 patients for whom surgery was delayed showed a favorable result. The unfavorable outcomes were also attributed by vasospasm or other medical problems. Conclusion: For further improvement of the overall surgical outcome: First, early surgical intervention is recommended for good grade patients. Second, active management of poor grade patients should be scrutinized with early surgery. Third, it is also important to step up the effort to minimize the risk of medical complications to enhance surgical results on top of the mainstay of prevention efforts for vasospasm and rebleeding.

• Proceedings of the Korean Vacuum Society Conference
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• 2014.02a
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• pp.174-174
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• 2014

Memristor devices are one of the most promising candidate approaches to next-generation memory technologies. Memristive switching phenomena usually rely on repeated electrical resistive switching between non-volatile resistance states in an active material under the application of an electrical stimulus, such as a voltage or current. Recent reports have explored the use of variety of external operating parameters, such as the modulation of an applied magnetic field, temperature, or illumination conditions to activate changes in the memristive switching behaviors. Among these possible choices of signal controlling factors of memristor, photon is particularly attractive because photonic signals are not only easier to reach directly over long distances than electrical signal, but they also efficiently manage the interactions between logic devices without any signal interference. Furthermore, due to the inherent wave characteristics of photons, the facile manipulation of the light ray enables incident light angle controlled memristive switching. So that, in the tautological sense, device orienting position with regard to a photon source determines the occurrence of memristive switching as well. To demonstrate this position controlled memory device functionality, we have fabricated a metal-semiconductor-metal memristive switching nanodevice using ZnO nanorods. Superhydrophobicity employed in this memristor gives rise to illumination direction selectivity as an extra controlling parameter which is important feature in emerging. When light irradiates from a point source in water to the surface treated device, refraction of light ray takes place at the water/air interface because of the optical density differences in two media (water/air). When incident light travels through a higher refractive index medium (water; n=1.33) to lower one (air; n=1), a total reflection occurs for incidence angles over the critical value. Thus, when we watch the submerged NW arrays at the view angles over the critical angle, a mirror-like surface is observed due to the presence of air pocket layer. From this processes, the reversible switching characteristics were verified by modulating the light incident angle between the resistor and memristor.

• Journal of Preventive Medicine and Public Health
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• v.53 no.5
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• pp.342-352
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• 2020

Objectives: The aim of this retrospective cohort study was to investigate whether non-alcoholic fatty liver disease (NAFLD) was associated with incident bone mineral density (BMD) decrease. Methods: This study included 4536 subjects with normal BMD at baseline. NAFLD was defined as the presence of fatty liver on abdominal ultrasonography without significant alcohol consumption or other causes. Decreased BMD was defined as a diagnosis of osteopenia, osteoporosis, or BMD below the expected range for the patient's age based on dual-energy X-ray absorptiometry. Cox proportional hazards models were used to estimate the hazard ratio of incident BMD decrease in subjects with or without NAFLD. Subgroup analyses were conducted according to the relevant factors. Results: Across 13 354 person-years of total follow-up, decreased BMD was observed in 606 subjects, corresponding to an incidence of 45.4 cases per 1000 person-years (median follow-up duration, 2.1 years). In the model adjusted for age and sex, the hazard ratio was 0.65 (95% confidence interval, 0.51 to 0.82), and statistical significance disappeared after adjustment for body mass index (BMI) and cardiometabolic factors. In the subgroup analyses, NAFLD was associated with a lower risk of incident BMD decrease in females even after adjustment for confounders. The direction of the effect of NAFLD on the risk of BMD decrease changed depending on BMI category and body fat percentage, although the impact was statistically insignificant. Conclusions: NAFLD had a significant protective effect on BMD in females. However, the effects may vary depending on BMI category or body fat percentage.

• Korean Journal of Cleft Lip And Palate
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• v.4 no.2
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• pp.9-18
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• 2001

Cleft lip and palate is the most frequent congenital facial deformity of the orofacial area. Successful management of patients with cleft lip and palate requires a multidisciplinary approach from birth to adult stage. The early surgical intervention of lip and palate induces a significant incidence of maxillary growth restriction that produces secondary deformities of the jaws, and the severity of the skeletal discrepancies tends to increase with growth. The early growth modification treatment to utilize the patient's growth potential is necessary in the cleft lip and palate patients, and we must consider not only the existing skeletal discrepancies but the residual growth amount and the direction. However, once we have obtained good results with orthopedic treatment in mixed dentition stage, we must pay special attention to maintain the treatment results because of high relapse tendencies and the alterations of jaw relationships due to residual growth.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2004.03a
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• pp.75-78
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• 2004

Various jet engines (Turbine engine family and RAM Jet engine) have been developed for high speed aircrafts. but their application to hypersonic flight is restricted by principle problems such as increase of total pressure loss and thermal stress. Therefore, the development of next generation propulsion system for hypersonic aircraft is a very important subject in the aerospace engineering field, SCRAM Jet engine based on a key technology, Supersonic Combustion. is supposed as the best choice for the hypersonic flight. Since Supersonic Combustion requires both rapid ignition and stable flame holding within supersonic air stream, much attention have to be given on the mixing state between air stream and fuel flow. However. the wider diffusion of fuel is expected with less total pressure loss in the supersonic air stream. So. in this study the direction of fuel injection is inclined 30 degree to downstream and the total pressure of jet is controlled for lower penetration height than thickness of boundary layer. Under these flow configuration both streams, fuel and supersonic air stream, would not mix enough. To spread fuel wider into supersonic air an aerodynamic force, baroclinic torque, is adopted. Baroclinic torque is generated by a spatial misalignment between pressure gradient (shock wave plane) and density gradient (mixing layer). A wedge is installed in downstream of injector orifice to induce an oblique shock. The schlieren optical visualization from side transparent wall and the total pressure measurement at exit cross section of combustor estimate how mixing is enhanced by the incidence of shock wave into supersonic boundary layer composed by fuel and air. In this study non-combustionable helium gas is injected with total pressure 0.66㎫ instead of flammable fuel to clarify mixing process. Mach number 1.8. total pressure O.5㎫, total temperature 288K are set up for supersonic air stream.

• Journal of the Korea Convergence Society
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• v.11 no.3
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• pp.135-143
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• 2020

Parkinson's Disease (PD) is one of the three major old-age onset neurodegenerative diseases, its incidence rate is increasing worldwide as being an aging society. The number of PD patients has increased from 3 million in 1990 to 6.2 million in 2015 and is expected to increase to 12.4 million by 2040. Although many therapeutic candidates have been under development, but not yet been suggested the therapeutics of PD. For analyzing the trends and the status of convergence of technologies in the PD therapeutics, we classified into six sub-categories using global patent information and analyzed the level of technical competitiveness and technology convergence according to year, country, applicant, and technical description. These results can be used as a fundamental understanding for the current technical trend and the status of convergence of PD therapeutics, and establish the direction and strategy of R&D.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.22 no.6
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• pp.429-436
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• 2010

Hydraulic experiments were conducted to analyze the characteristics of stem waves due to multidirectional random wave incidence with the different incident angles of main wave direction. Both multi-directional and uni-directional random waves were used to generate the stem waves and their results were compared with each other. The experiment shows multi-directional random waves developed along the vertical wall tend to increase as the incident angle increases similar to the uni-directional waves. Moreover, the stem wave widths were almost same as those in uni-directional random wave cases. However, the experiment demonstrate the stem wave heights were significantly smaller in multi-directional random wave cases than in uni-directional random wave cases.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.24 no.2
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• pp.353-371
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• 2014

We already have seen many studies and articles about the methodology responding the security risks and threats. But we still have some controversial subjects to be settled. Now, we are living in the era that we should focus on how to use the security systems instead of how to make it. In this point of view, a company need to find out the answer for these questions, which security risks have to be handled in a corporate, which system is better for responding the security threats, and how we can build necessary security architecture in case of developing systems. In this article, we'd like to study on-site scenarios threatening the corporate assets, the limit on dealing with these threats, and how to consolidate the security events and information from enormous assets. Also, we'd like to search for the direction form the actual cases which have shown the desired effect from converging the assets and network informations.