• Journal of the Institute of Electronics Engineers of Korea SP
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• v.42 no.1
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• pp.71-77
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• 2005

In this paper we implement a headphone-based 5.1 channel 3-dimensional (3D) sound generation system using HRTF (Head Related Transfer Function). Each mono sound source in the 5.1 channel signal is localized on its virtual location by binaural filtering with corresponding HRTFs, and reverberation effect is added for spatialization. To reduce the computational burden, we reduce the number of taps in the HRTF impulse response and model the early reverberation effect with several tens of impulses extracted from the whole impulse sequences. We modified the spectrum of HRTF by weighing the difference of front-back spec01m to reduce the front-back confusion caused by non-individualized HRTF DB. In informal listening test we can confirm that the implemented 3D sound system generates live and rich 3D sound compared with simple stereo or 2 channel down mixing.

• Transactions of the Korean Society of Automotive Engineers
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• v.14 no.6
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• pp.184-189
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• 2006

Tumble flow test rig has been used as the useful tool in the developing intake system because major flow pattern induced by intake port of DOHC engine is tumble. Angular momentum of in-cylinder tumble flow can not be directly measured by impulse torque meter in the test rig like that of in-cylinder swirl flow due to rotational axis of the flow. Therefore the adaptor to transform tumble to swirl flow must be adapted in the test rig. In this study, using the commercial CFD code STAR-CD, we studied the effects on measured results due to the variation of the major design variables in the adaptor, tube length(L), tube diameter(D) and cylinder height(H). The effect of the attached angle($\theta$) of the test head to the adaptor also was simulated.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2007.11a
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• pp.139-143
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• 2007

The overall results of combustion tests performed for a 30 tonf-class full-scale combustion chambers of a liquid rocket engine were described. The combustion chambers have chamber pressure of 53${\sim}$60 bar and propellant mass flow rate of 89 kg/so The combustion chamber is composed of mixing head, SUS baffle, baffle injector, ablative chamber, channel cooling chamber and regenerative cooling chamber. The test results show that the combustion characteristic velocity is in the range of 1673${\sim}$1730 m/sec and the specific impulse of the combustion chamber is in the range of 254${\sim}$263 sec. As the recess number of the injectors increases, the combustion characteristic velocity increases. And as the combustion characteristic velocity increases, the specific impulse of the combustion chamber also increases.

• The Journal of Korean Academy of Orthopedic Manual Physical Therapy
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• v.7 no.2
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• pp.51-56
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• 2001

The purpose of this study is to make a new diagnostic test model for the physical disturbance signs for the overuser or addiction persons in internet. Variations of Somato-diagnostic testR for Internet Addiction Syndrome(Park V1.0) are follows ; 1. Are you hurt in your elbow or shoulder? 2. Do you feel stiffness in your neck? 3. Do you feel numbness of wrist on drive? 4. Are you hurt in your fingers on touch a keyboard or mouse? 5. Are you hurt in your back? 6. I feel taut on my legs sometimes. 7. I feel dim or bloodshot in my eyes. 8. I feel dry in my eyeball. 9. I feel heavy and ache on my head. 10. I can't sleep very well. 11. I have a digestive upset often. 12. My hand's full with sweat on computing. 13. I feel tremble or heavy in my heart. 14. I'm tired easily. 15. I'm not concerned about a sex impulse at all.

• Transactions of the Korean Society of Machine Tool Engineers
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• v.16 no.4
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• pp.13-21
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• 2007

This paper presents characteristics of steady flow by variation of a combustion chamber and an intake port. Gas flow field inside a combustion chamber is the important factor in improving combustion stability and reduction of emission level. The flow characteristics such as flow coefficient, tumble ratio and swirl ratio are measured by the steady flow rig test with an impulse meter in this study. In the measuring, the valve lifts are varied between 1mm to 10mm. The three combustion chambers and two intake ports were applied to the steady flow apparatus in order to investigate the effect of swirl and tumble on the in-cylinder flow. As a result, tumble ratio were found to be different by variation of the combustion chambers and the intake ports. The data from the present study can be applied to design of a similar engine as basic data.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.21 no.7
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• pp.948-961
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• 1997

The effects of intake port eccentricity and a partition between the two intake ports on the incylinder swirl characteristics in a 4 valve diesel engine having the two intake ports, one is a helical intake port and the other is a tangential intake port, were investigated by using the impulse swirl meter(ISM) in a steady flow test rig. Mean flow coefficient ( $C_{f(mean)}$, swirl ratio ( $R_{s}$) and the mass flowrate through the two intake ports with and without intake port partition were measured. The results showed that the characteristics of in-cylinder swirl ratio formed by a 4-valve cylinder head were largely affected by valve eccentricity ratio ( $N_{y}$) and the existence of an intake port partition between the two intake ports. Mean flow coefficient ( $C_{f(mean)}$) increases and swirl ratio ( $R_{s}$) decreases in case of being the partition between the two intake ports. And also the mass flowrate through the tangential intake port is 19.0% and 7.7% more than that of the helical intake port in case of the two intake ports with and without partition respectively.ively.

• Transactions of the Korean Society of Automotive Engineers
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• v.5 no.5
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• pp.157-169
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• 1997

The effects of intake port eccentricity on the characteristics of in-cylinder swirl ratio in a 4-valve diesel engine having the two intake ports; one is a helical intake port and the other is a tangential intake port were investigated by using the ISM(impulse swirl meter) in steady flow test rig. Swirl ratio($R_s$) and mean flow coefficient($C_{f(mean)}$) with valve eccentricity ratio($N_y$) and axial distance(Z/B) were measured. As the results from this experiment, the characteristics of in-cylinder swirl ratio formed by a 4-valve cylinder head were largely affected by intake port eccentricity. There is a difference in the mass flowrate through the two intake ports, and the mass flowrate through the tangential intake port is 19% more than that of the helical intake port. Therefore, we could know that the effects of the mass flowrate ratio through each intake port besides intake port shape should be conidered.

• Ocean and Polar Research
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• v.31 no.1
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• pp.1-9
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• 2009

When evaluating acoustic methods for measuring physical parameters in the ocean, economical and technical considerations are paramount. As an indirect method of estimating ocean dynamics, acoustic tomography has advantages over more conventional approaches. It allows the reconstruction of temperature and flow fields from the acoustic impulse time-of-flight measured along the rays propagating from the source to the receiver. However, many problems require complicated and expensive systems. To use the acoustic tomography method to best effect, developing hardware systems with sources and receivers mounted permanently on the sea bottom is crucial. Akulichev et al. presented some experimental results from shallow zones of the World Ocean that served as a motive for developing a multifunction system with acoustic hardware and software. Here we present technical features and the sea test results of the system.

• International Journal of Naval Architecture and Ocean Engineering
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• v.3 no.1
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• pp.20-26
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• 2011

A weakly nonlinear seakeeping methodology for predicting motions and loads is presented in this paper. This methodology assumes linear radiation and diffraction forces, calculated in the frequency domain, and fully nonlinear Froude-Krylov and hydrostatic forces, evaluated in the time domain. The particular approach employed here allows to overcome numerical problems connected to the determination of the impulse response functions. The procedure is divided into three consecutive steps: evaluation of dynamic sinkage and trim in calm water that can significantly influence the final results, a linear seakeeping analysis in the frequency domain and a weakly nonlinear simulation. The first two steps are performed employing a three-dimensional Rankine panel method. Nonlinear Froude-Krylov and hydrostatic forces are computed in the time domain by pressure integration on the actual wetted surface at each time step. Although nonlinear forces are evaluated into the time domain, the equations of motion are solved in the frequency domain iteratively passing from the frequency to the time domain until convergence. The containership S175 is employed as a test case for evaluating the capability of this methodology to correctly predict the nonlinear behavior related to wave induced motions and loads in head seas; numerical results are compared with experimental data provided in literature.

• Journal of Medicine and Life Science
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• v.16 no.3
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• pp.64-75
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• 2019

Vertigo and dizziness are common symptoms with various etiologies and pathogeneses. Vertigo is an illusion of motion due to disease of the vestibular system, usually a sense of rotation. Dizziness, a term that represents a wide range of non-vertigo symptoms, is commonly associated with non-vestibular disorders including old age, cardiac syncope, orthostatic hypotension, metabolic disease, anxiety, and drugs. Vertigo should be determined whether the cause is central or peripheral. Peripheral vertigo is usually benign but central vertigo is serious and often require urgent treatment. The careful history and detailed physical examinations(pattern of nystagmus, ocular tilt reaction, head impulse test and positional tests such as Dix-Hallpike maneuver) provide important clues to the diagnosis of vertigo. Most of patients have benign peripheral vestibular disorders - vestibular neuritis, benign paroxysmal positional vertigo (BPPV), and Meniere's disease. BPPV is a leading cause of peripheral vertigo and can easily be cured with a canalith repositioning maneuver. In this review, a focus is on the differential diagnosis of common vestibular disorders with peripheral and central causes.