• Journal of KSNVE
• /
• v.4 no.1
• /
• pp.23-31
• /
• 1994

When a shaft is misaligned, a high level of vibration is experienced. As a consequence, the system performance could be low with high level of noise generated. Even, a catastrophic damage of the rotating machinery may happen in the worst situation. The vibration caused by the shaft misalignment is not cured unless a correct alignment of the shaft is investigated. In this paper, a step by step approach for the turbine alignment has been demonstrated. It includes measurement tips of the coupling rim and face, calculation procedure of the bearing level, and the relevant values of the addition and subtration for shims in order to align the shaft level correctly. Then, as an application of the shaft alignment, the turbine system at the Pyung Tek focile electric power plant has been examined. Since the real system consists of high pressure, low pressure turbines and the generator, detailed alignment prolcedures of the multi stage shaft system has been demonstrated.

• Journal of the Korean Society for Aeronautical & Space Sciences
• /
• v.30 no.8
• /
• pp.112-119
• /
• 2002

Three dimensional numerical heat transfer analysis was carried out against periodically arranged fuel injectors of the liquid rocket engine. A finite volume method based on SIMPLE algorithm was adapted which gave a good agreement with the published results of the heat transfer problem of a backward facing step. The Nusselt number and pressure drop increased as the distance between the injector elements decreased. When the Reynolds number increased, the Nusselt number increased but nondimensionalized pressure drop decreased slightly.

• KDI Journal of Economic Policy
• /
• v.41 no.4
• /
• pp.1-44
• /
• 2019

The contingent convertible bond (or CoCo) is designed as a bail-in tool, which is written down or converted to equity if the issuing bank is seriously troubled and thus its trigger is activated. The trigger could either be rule-based or discretion-based. I show theoretically that the bail-in is less implementable and that the associated bail-in risk is lower if the trigger is discretion-based, as governments face greater political pressure from the act of letting creditors take losses. The political pressure is greater because governments have the sole authority to activate the trigger and hence can be accused of having 'blood on their hands'. Furthermore, the pressures could be augmented by investors' self-fulfilling expectations with regard to government bailouts. I support this theoretic prediction with empirical evidence showing that the bail-in risk premiums on CoCos with discretion-based triggers are on average 1.13 to 2.91%p lower than CoCos with rule-based triggers.

• Journal of Ocean Engineering and Technology
• /
• v.34 no.2
• /
• pp.97-109
• /
• 2020

In this study, ultimate strength characteristics of clamped sandwich panels with metal faces and an elastic isotropic core under combined in-plane compression and lateral pressure loads are investigated to verify the applicability of the ultimate strength design formula for ship structures. Alternative elastomer-cored steel sandwich panels are selected instead of the conventional bottom stiffened panels for a Suezmax-class tanker and then the ultimate strength characteristics of the selected sandwich panels are examined by using nonlinear finite element analysis. The change in the ultimate strength characteristics due to the change in the thickness of the face plate and core as well as the amplitude of lateral pressure are summarized and compared with the results obtained by using the ultimate strength design formula and nonlinear finite element analysis. The insights and conclusions developed in the present study will be useful for the design and development of applications for sandwich panels in double hull tanker structures.

• Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
• /
• 1989.10a
• /
• pp.9-12
• /
• 1989

ABSTRACT -- Recently, a method of magnetically-enhanced discharge columns is considered to increase the luminous efficacy of discharge lamps, which is based upon the face that the diffusion motion of charged particles in the discharge column strongly depends on the applied magnetic fields. This study investigates the effect of applied transverse magnetic fields on the light output of low-pressure Hg-Ar discharge. As a result, it is found that the electric field in the positive column increases according to the applied megnetic field, which causes an increase in the total light output. And this effect is much more pronounced upon the spectral line originating form the higher levels.

• Journal of the Korean Society for Precision Engineering
• /
• v.17 no.11
• /
• pp.88-93
• /
• 2000

Recently the gear design focuses on the optimal design to extract the design factors from the vehicle transmission that is required to equip the powerful, speedy and silent characteristics. In this study, we had determined modules($m_n$) and face widths (b) to sustain strengths of contact and bending. The pressure angle ($\alpha$) and the helix angle ($\beta$) also had been obtained from the constraint of a contact ratio ($\varepsilon) on helical gears. Through the optimal design algorithm suggested in this study, the design factors were calculated on vehicle transmission gears and those determined factors were able to firm a suitability of the design.

• Journal of Preventive Medicine and Public Health
• /
• v.33 no.2
• /
• pp.208-214
• /
• 2000

Objectives : Face-to-face interviews were conducted to investigate the relationship between blood pressure and the impairment of cognitive function in rural elderly (N=932) aged 60-64 in Dalsung County, April to September in 1996 Methods : Impairment of cognitive function was defined as a score of less than 23 by the Korean version of the Mini-Mental State Examination (MMSEK). Blood pressure was measured once in each subject using a portable automatic sphygmomanometer. Results : By univariate logistic regression on males, no category of systolic blood pressure bore statistical significance. Groups with diastolic blood pressures of, less than 80 mmHg, 90-94 mmHg, and more than 95mmHg had odds ratios of more than one compared with the reference group (80-89 mmHg). This was most significant in the group with blood pressures lower than 80 mmHg, which had a statistically significant odds ratio of 1.68 (95% confidence interval CI; 1.02-2.75). No category of blood pressure was statistically significant in females. Multivariate logistic regression for males, with adjustment for age, educational attainment, smoking, alcoholic drinking, body mass index, atherosclerotic disease, and antihypertensive medication use, did not alter the odds ratios significantly in terms of systolic blood pressure. However, the group with diastolic blood pressure of less than 80 mmHg had an increased odds ratio of 2.01 (95% CI; 1.15-3.52) compared with the reference group. In females, systolic blood pressure did not alter the odds ratio, but the group with a diastolic blood pressure of less than 80 mmHg had a statistically significant odds ratio of 0.57 (95% CI; 0.37-0.89). Conclusions : These results suggest that the relationship between blood pressure and cognitive function status is stronger diastolic than systolic blood pressure and that there is a complex relationship between blood pressure and cognitive function by sex.

• Computational Structural Engineering
• /
• v.9 no.4
• /
• pp.189-198
• /
• 1996

The fracture behaviour of concrete gravity dam mainly due to uplift pressure acting at the crack face was studied. Triangular type and parabolic type distribution of the uplift pressure including uniform type were first considered in case of calculating stress intensity factor(SIF) by the surface integral method. Second, the directions of crack propagation according to the uplift pressure distribution were pursued by FRANC(FRacture ANalysis Code). Third, critical crack lengths according to the uplift pressure distribution under the overflow depth were calculated. The SIF values obtained from the surface integral method were compared with those by FRANC and relatively good agrements could be obtained between both of them. And it could be seen that the direction of crack propagation in case of triangular pressure distribution was a little benter to the dam base than the one by the uniform type. Maximum critical crack lengths under the overflow depth were obtained at about 2/5-1/2 of the dam height.

• The Journal of the Korea institute of electronic communication sciences
• /
• v.14 no.6
• /
• pp.1257-1264
• /
• 2019

The traditional cuff-based method for BP(Blood Pressure) measurement is not suitable for continuous real-time BP measurement techniques. For this reason, the previous studies estimated various blood pressures by fusion with the electrocardiography (ECG) and photoplethysmogram (PPG) sensor signals. However, conventional techniques based on PPG bio-sensing measurement face many challenging issues such as noisy supply fluctuation, small pulsation, and drifting non-pulsatile. This paper proposed a novel BP estimation methods using PPG and ECG sensors, which can be derived from the relationship between PPG and ECG using PTT(Pulse Transit Time) and PWV(Pulse Wave Velocity). Unlike conventional height ratio features, which are extracted on the basis of the peaks in the PPG and ECG waveform. The proposed method can be reliably obtained even if there are missing peaks among the sensed PPG signal. The increased reliability comes from periodical estimation of the peak-to-peak interval time using ECG and PPG. After 250,000 times trials of the blood pressure measurement, the proposed estimation technique was verified with the accuracy of ±28.5% error, compared to a commercialized BP device.

• Journal of Korean Society of Coastal and Ocean Engineers
• /
• v.23 no.2
• /
• pp.139-146
• /
• 2011

The breaking wave pressure occurs when a plunging breaker instantaneously impinges on structural surface, and appears differently depending on whether or not to form air pockets at the instant of contact. The Wagner type normally forms a single pressure peak at the contact spot due to the direct collision of water volume to the structure whereas in the Bagnold type the time lagged oscillation of the air pocket causes pressure peaks even at areas away from the spot. In the present study, the Bagnold's impact pressure is numerically and experimentally investigated for the bulkhead of an underwater tunnel under construction which is subjected to nearby breaking waves. A numerical solver of Navier-Stokes equations was applied to reproduce the breaking waves near a bulkhead, and the results showed the Bagnold's impact pressure occurring on the back (land side) face of the bulkhead. The existence of the impact pressure was also verified by a hydraulic model testing, and it was found that the experimental results well conformed to their numerical counterparts.