• Journal of the Korean Institute of Electrical and Electronic Material Engineers
• /
• v.28 no.6
• /
• pp.360-364
• /
• 2015

Electronic systems based on solid state devices have changed to be more complicated and miniaturized as the electronic systems developed. If the electronic systems are exposed to HPEM (high power electromagnetics), the systems will be destroyed by the coupling effects of electromagnetic waves. Because the HPEM has fast rise time and high voltage of the pulse, the semiconductors are vulnerable to external stress factor such as the coupled electromagnetic pulse. Therefore, we will discuss about malfunction behavior and DFR (destruction failure rate) of the semiconductor caused by amplitude and repetition rate of the pulse. For this experiment, the pulses were injected into the pins of general purpose IC due to the fact that pulse injection test enables the phenomenon after the HPEM is coupled to power cables. These pulses were produced by pulse generator and their characteristics are 2.1 [ns] of pulse width, 1.1 [ns] of pulse rise time and 30, 60, 120 [Hz] of pulse repetition rate. The injected pulses have changed frequency, period and duty ratio of output generated by Timer IC. Also, as the pulse repetition rate increases the breakdown threshold point of the timer IC was reduced.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 1999.11a
• /
• pp.339-342
• /
• 1999

The equation of output voltage from the PVDF was derived. When impact force applied to the PVDF films of cantilever beam and one-end fixed, other-end supported beam structure, output voltage equation induced. Experimental output voltages by falling ball agreed quite well with induced theoretical data. This PVDF film showers to be in high possibility in a warning system of abnormal pulse rate and breathing, and in detecting impact force and/or mechanical energy.

• Journal of Welding and Joining
• /
• v.33 no.1
• /
• pp.7-13
• /
• 2015

Magnetic pulse welding(MPW) is a solid state welding process that is accomplished by a magnetic pulse causing a high-velocity impact on two materials, resulting in a true metallurgical bond. One of the great advantages of MPW is that it is suitable for joining dissimilar metals. No heat affected zones are created because of the negligible heating and the clean surfaces formation that is a consequence of the jet and the metal is not degraded. Also, compared to other general welding processes, this process leads to only a low formation of brittle intermetallic compounds However, although this process has many advantages its application to industrial fields has so far been very low. Therefore, in this study we are presenting the principles, apparatus and application of MPW for application the industrial fields.

• Proceedings of the Korean Geotechical Society Conference
• /
• 2009.09a
• /
• pp.1100-1106
• /
• 2009

This study intends to develop a pulse discharge device to strengthen the pushing power by expanding the cavity of the anchor settlement to form a spheric root for the purpose of constructing the economical and stable anchor. and, a series of field test were carried out in order to check applicability of machines of pulse powered underreamed anchors. Through the experiments, the electrical characteristics of the pulse power equipment had been identified it and the dynamic pressure generated from the subsequent change had been measured. Here, the measured dynamic pressure is the cavity expansion pressure to impact on the ground around the anchor settlement. Since this pressure has effects of cavity expansion and bored surface hardening with dynamic hardening effects on the anchor settlement, it is expected that it will largely contribute the increase of pushing power with a strong frictional resistance.

• The Journal of the Acoustical Society of Korea
• /
• v.35 no.2
• /
• pp.158-165
• /
• 2016

Many researches for improving detection performance in the reverberation environment have been conducted in active sonar systems. Especially the type of active pulse makes an impact on the detection performance in the reverberation environment. Thus, this paper describes the detection performance of PTFM (Pulse Trains of Frequency Modulated waveform), Costas, and Geometric Comb pulses which are known for their outstanding performance against the reverberation. Sea trial data of those pulses was analyzed and it was figured out that the range resolution of PTFM pulse was deteriorated by its sub-pulses. Costas pulse showed performance degradations of the doppler resolution by multipath signals. Geometric Comb pulse showed the best doppler resolution.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
• /
• v.12 no.3
• /
• pp.284-291
• /
• 2000

A basic pulse tube refrigerator has been constructed with extensive instrumentation to study the characteristics of the heat exchanger experimentally under the oscillating pressure and the oscillating flow. This paper describes the sequential experiments with the basic pulse tube refrigerator. The experiments were performed for various cycle frequencies under the square pressure wave forms. First, the heat flux was measured through the cycle at the both cold and warm end heat exchangers without the regenerator. In order to enhance the thermal communication capability of the heat exchanger with the gas at low operating frequencies, a unique design of the triangular shape radial fin concept was applied to the heat exchangers. For the fin heat exchanger, the measured heat flux and the calculated heat flux from the two well-known oscillating heat transfer correlations were compared and discussed. Second, the regenerator was added to the pulse tube to make a basic pulse tube refrigerator configuration. The experiment showed the great impact of the regenerator on the temperature and the heat flux profiles. At the warm-end, the cyclic averaged heat flux had its maximum value at the specific operating frequency. The paper presents the explanation of the surface heat pumping effect as well as the experimental data.

• Journal of Korean Medical classics
• /
• v.31 no.3
• /
• pp.33-58
• /
• 2018

Objectives : Literatures related to Bianque are studied to discover the path of development and the impact of Bianque school's pulse diagnosis system. Methods : Texts regarding Bianque were searched in history books such as Shiji and Zhanguoce, and medical texts such as the medical books of Mawangdui Han Tomb, Huangdineijng, Maijing, and Qianjinyifang to understand how the Bianque school's pulse diagnosis system was developed. Results : 1. Bianque school's pulse diagnosis system was used to inspect the distribution pattern of blood vessels and discover the location of the disease including the palpatation realm such as only hard or only fall. 2. The system of inspection was created when the diagnosis method that uses the color of the pulse by using the color of blood vessels was added to the diagnostic method of pulse condition. 3. Adding the concept of pulse to the visual information that derives from pulse condition becomes pulsation. This is a diagnostic method that falls under the realm of palpation, and it was used to discover the location of disease. 4. The qi of pulse is motor that induces pulse, and this concept is used in order to understand how normal and abnormal pulsations appear, and to treat the circulation disorder of qi and blood. 5. Cubit skin examination is a method that comprehensively take into account the upper arm skin's cold and heat, slippery and roughness, and relax and tension state. This method was used together with other diagnostic methods. As described above, it seems that the diagnostic method with blood vessels used by Bianque school seems to have developed from Bianque's special inspection ability to the stage where it uses palpation, and then to the stage of cubit skin examination which uses both palpation and inspection.

• Journal of the Korean Society for Nondestructive Testing
• /
• v.19 no.4
• /
• pp.259-269
• /
• 1999

Elastic wave velocity measurement technique such as impact-echo method and ultrasonic pulse velocity method has been successfully used to evaluate the moduli and strength of concrete. However, estimation results obtained by the NDT methods do not agree well with real things because longitudinal wave velocity is influenced by various factors. In this paper, among several factors influencing P-wave velocity, the influence of moisture content in concrete was investigated through the experiment. Test results show that longitudinal wave velocity is significantly affected by the moisture content of concrete, i.e., the lower moisture content. the lower velocity. Moisture content influences rod-wave velocity measured by impact-echo method stronger than ultrasonic pulse velocity measured by transmission method. During drying process with ages. the difference of increasing rate between longitudinal wave velocity and compressive strength of concrete is gradually increased. Therefore, to establish more accurate relationship between longitudinal wave velocity and strength, the difference of the increasing rate should be considered.

• Journal of the Society of Naval Architects of Korea
• /
• v.35 no.1
• /
• pp.72-79
• /
• 1998

Static deformation theory of elastoplastic structures can be applied only if the magnitude of loading is less than the plastic collapse force $F_c$. However, with impact or explosive blast loading, the structure can be subjected to an intense but short-duration force pulse that exceeds the plastic collapse force and initiates structural collapse. In this paper, the dynamic response of a rigid-perfectly plastic cantilever subject to intense impact loading is examined in terms of the plastic collapse force. When a step loading is applied, the motion of the beam is calculated and analyzed through the non-dimensionalization of variables. It is concluded that the motion of a beam can be characterized as a function of the nondimensionalized force parameter, $f{\equiv}F/F_c$, where $F_c$ represents the critical force for plastic collapse. This result is used to the analysis of the beam motion subject to rectangular force pulse.

• Transactions of the Korean Society of Automotive Engineers
• /
• v.8 no.1
• /
• pp.101-109
• /
• 2000

Occupant protection in the side impact of a car became one of the most important issues of car crashworthiness due to high injury level in a side impact crash. An accurate simulation of the side impact crash is an essential tool for the reduction of development time and cost for side impact safety system. This paper describes a new test methodology that can accurately generate the crash pulses of a vehicle and a door in a very cost-effective manner, and then evaluates the injury values of the dummy for the various sled pulses. This test methodology is simple and easy to approach because the door velocity is controlled by the hydraulic actuator and brake and the seat velocity is only adjusted by the friction force of the hydraulic brake. The superiority of the proposed test methodology is proven by the evaluation of dummy's injury values according to the change of the pressure of the hydraulic brake and by the application as a tool for the development of side airbag.