• Journal of the Korean Society for Aviation and Aeronautics
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• v.15 no.1
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• pp.1-10
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• 2007

When detonation is occurred, the working fluid is compressed itself, though there are no other devices that compress the fluid. As a result, an engine which uses detonation for a combustion process doesn't need moving parts so that the engine can be lighter than other engines ever exist, and such an engine is often referred to as a pulse detonation engine. Since using detonation has higher performance than using deflagration, many studies have been attempting to control and analyze the engines using detonation as combustion. The purpose of this study is to analyze the hybrid cycle which is consisted of Brayton and Pulse Detonation Engine cycle. At first, we set the theoretical basis of detonation analysis, and after that we consider two hybrid cycles; a turbojet hybrid cycle and a turbofan hybrid cycle. The more energy released, the higher detonation Mach number the detonation wave has. In general, a cycle which has a detonation process has higher performances but thermal efficiency of hybrid turbofan engine.

• Journal of the Korean Ceramic Society
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• v.51 no.5
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• pp.447-452
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• 2014

This paper presents the effects of pulse plasma parameters such as duty cycle and pulse frequency on the properties of TiAlN coatings deposited by asymmetric bipolar pulsed DC magnetron sputtering systems. The results show that, with decreasing duty cycle and increasing pulse frequency, the coating morphology changes from a columnar structure to a dense structure with finer grains. Pulsed sputtered TiAlN coatings showed higher hardness, higher residual stress, and smaller grain sizes than did DC prepared TiAlN coatings. Moreover, residual stress and nanoindentation hardness of pulsed sputtered TiAlN coatings increased with increasing pulse frequency. Meanwhile, the surface roughness decreased continuously with increasing pulsed DC frequency up to 50 kHz.

• Journal of Physiology & Pathology in Korean Medicine
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• v.23 no.1
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• pp.186-191
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• 2009

In the study on the waveform analysis of radial artery pulse diagnosis, we need to establish fundaments of contemporary pulse diagnosis research. As we will to do experimental research on the difference of pulse waveform on the radial artery with applied variations of pressure(5 stage-pressure) and measuring position(CHON, KWAN, CHEOG). First of all, in this research, we did the experiment of the study on the waveform analysis of radial artery(left KWAN) pulse dignosis by using 3 dimension pulse meter and analyzer (3D MAC). As a result. we extracted the seven measurement fluents : energy(E), size of cycle(h1), size of reflection cycle(h2), time of reflection cycle(t2), time of contraction (t4), width of cycle(w), area of waveform(A) by the statistically reasonable differences. We expect that the seven measurement fluents contribute to divide the situation through the results of waveform analysis of radial artery.

• Korean Journal of Materials Research
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• v.8 no.5
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• pp.377-382
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• 1998

Atomic layer deposition(ALD) of amorphous TiN films on $SiO_2$ between 17$0^{\circ}C$ and 21O$^{\circ}C$ has been investigated by alternate supply of reactant sources, Ti[N($C_2,H_5,CH_3)_2]_4$ [tetrakis(ethylmethylamminoltitanium: TEMAT] and $NH_3$. Reactant sources were injected into the reactor in the order of TEMAT vapor pulse, Ar gas pulse, $NH_3$. gas pulse and Ar gas pulse. Film thickness per cycle was saturated at around 1.6 monolayer(MU per cycle with sufficient pulse times of reactant sources at 20$0^{\circ}C$. The results suggest that film thickness per cycle could be beyond 1 MLicycie in ALD, which were explained by rechemisorption mechanisms of reactant sources. The ideal linear relationship be¬tween number of cycles and film thickness is confirmed. As a results of surface limited reactions of ALD, step cover¬age was excellent. Particles caused by the gas phase reactions between TEMAT and NH3 were almost free because TEMAT was seperated from $NH_3$ by the Ar pulse. In spite of relatively low substrate temperature, carbon impurity was incorporated below 4 at%.

• The Journal of Korean Obstetrics and Gynecology
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• v.30 no.4
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• pp.77-88
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• 2017

Objectives: The purpose of this study is to analyze the characteristics of the pulse energy in women with PCOS (Polycystic ovary syndrome) compared with women who have a regular menstrual cycle. Methods: We analyzed the values of pulse energy on 20 patients with PCOS as an experimental group and 40 patients with regular menstrual cycle as a control group. Control group was divided into 20 women with follicular phase and 20 women with luteal phase respectively. Statistical analysis was performed using SPSS/Win 18.0, one way ANOVA and Tukey HSD. Results: The results were as follows. 1. The mean pulse energy of the Right Chon was significantly increased compared with those of the Left Kwan and the Right Kwan among PCOS group. 2. There were no statistically significant pulse energy among control groups. Conclusions: The pulse energy of Lung is bigger than that of Spleen and Liver in PCOS patients compared with women who have a regular menstrual cycle.

• Proceedings of the KSME Conference
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• 2001.06d
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• pp.636-641
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• 2001

In this paper, we constructed four valve type pulse tube refrigerator and found the characteristic of orifice (needle valve) opening for using phase shifter and optimum cycle time - The valve timing was controlled by the digital timers. The experimental results showed the optimum frequence and cycle time at operating conditions. The results showed that the optimum process time existed and the rate was same at each operating frequence. The no- load temperature of the refrigerator was 85K.

• Proceedings of the Materials Research Society of Korea Conference
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• 2012.05a
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• pp.90.1-90.1
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• 2012

1934년 J. R. Winkler에 의해 처음으로 개발된 pulse current 도금은 연속적인 직류 단속을 이용한 전기도금으로써 종래의 연속적인 직류(direct current) 전기 도금이 가지는 다공성 및 거친 도금 등의 한계를 극복하기 위해 연구되고 있다. 최근 전기 전자 산업의 급속한 발달과 함께 Au, Pd, Rh 등의 귀금속 도금에 있어서 Pulse 도금은 광택, 다공도, 내부 응력, 불순물 및 수소 함유량의 감소와 같은 특성 향상을 가질 수 있으며 기존 DC 전기 도금의 문제점 해결책으로서 많은 연구가 이루어지고 있다. 하지만 현재까지 Pulse 도금의 정확한 기구(mechanism)에 대한 명확한 정립이 되어 있지 않아 모든 도금계에 적용할 수 있는 standard pattern이 없는 실정이다. 본 연구에서는 귀금속 도금 중 Ag pulse 도금에 있어서 Peak current density, duty cycle, time이 Ag 도금의 표면 형상, 두께, 열전도율에 미치는 영향에 대해 연구하였다.

• Journal of the Korean Ceramic Society
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• v.54 no.1
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• pp.33-37
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• 2017

Single phase niobium nitride (NbN) coatings were deposited using asymmetric bipolar pulsed dc sputtering by varying pulse frequency and duty cycle of pulsed plasmas. Crystal structure, microstructure, morphology and mechanical properties were examined using XRD, FE-SEM, AFM and nanoindentation. Upon increasing pulse frequencies and decreasing duty cycles, the coating morphology was changed from a pyramidal-shaped columnar structure to a round-shaped dense structure with finer grains. Asymmetric bipolar pulsed dc sputtered NbN coatings deposited at pulse frequency of 25 kHz is characterized by higher hardness up to 17.4 GPa, elastic modulus up to 193.9 GPa, residual compressive stress and a smaller grain size down to 27.5 nm compared with dc sputtered NbN coatings at pulse frequency of 0 kHz. The results suggest that the asymmetric bipolar pulsed dc sputtering technique is very beneficial to reactive deposition of transition-metal nitrides such as NbN coatings.

• The Journal of the Society of Korean Medicine Diagnostics
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• v.10 no.2
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• pp.132-150
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• 2006

Objectives : The objective is that we measure and analyze Pulse-Respiration Ratio and Body Composition Analysis to study the correlation between both. Methods : First, after subjects take a rest over 10 minutes, we measure their electrocardiogram and respiration pattern through which we take average peak interval to calculate an average pulse cycle and a respiration cycle. An average respiration cycle divided by an average Pulse Rate gives Pulse-Respiration Ratio. Next, we draw out 22 Body Composition Analysis indicators by using In-Body 720 model. Last, we analyze and take statistics on them by using SPSS 13.0 program. Results : Negative is the correlation between P/R Ratio and Body Composition Analysis indicator like fatness degree, body fat volume, body fat rate, abdominal fatness, BMI. Conclusions : 1. The higher P/R Ratio the more likely to be thin, the lower P/R Ratio the more likely to be fat. 2. We separately analyze P/R Ratio depending on each breathing frequency and pulse frequency to find out that breathing frequency has great influence and that breathing frequency decides the fatness degree. 3. In study on the correlation between P/R Ratio and Body Composition Analysis, fatness degree, in-body fat volume, in-body fat rate, BMI are the related indicators, which shows the connection with the fatness indicators. 4. In study on the correlation between Han-Yeol [寒熱] grade and Body Composition Analysis indicators, the result is that Han[寒] has no connection and that only Yeol[熱] grade has something to do with it, which means the higher heat symptom subjects have, the more basic metabolism volume and muscular build they have.

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