• 한국정밀공학회지
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• 제17권2호
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• pp.51-57
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• 2000

An automotive wheel bearing is one of the most important components to guarantee the service life of a passenger car. The endurance lift of a bearing is affected by many parameters such as material properties, heat treatment, lubrication conditions, temperature, loading conditions, geometry, internal clearance and so on. Under the same geometry and loading conditions, the internal clearance is the most effective parameters on the endurance lift of a bearing. Generally, bearings have the longest lift with a little negative internal clearance. But it is very difficult to measure and modify the internal clearance after a wheel bearing is assembled. In this paper, we analyze the effect of an assembling procedure on the clearance of wheel bearings and suggest a method to determine optimal clearance for automotive wheel bearings by selecting initial bearing clearance.

• 한국전기전자재료학회논문지
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• 제14권11호
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• pp.898-903
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• 2001

In this study, we investigated amounts, distributions and sizes of pores of multilayer piezoelectric transformer, and predicted heat emission property and electrical characteristics according to designs of internal electrode. Forming densities of device having MLC, fingered and full filled internal electrode structure were 4.73 g/㎤, 4.80 g/㎤, 4.82 g/㎤ and forming porosities were 17.3737%, 13.1475%, 12.6121%, respectively. And sintered densities of MLC structured, fingered and full filled devices were 7.76 g/㎤, 7.75 g/㎤, 7.84 g/㎤ and sintered porosities were 4.0967%, 2.7132%, 2.5317%, respectively. Therefore, we concluded that fingered and full fi1led internal electrode devices, expecially, fingered internal electrode devices had cost-effective effect and maximum poling effect due to higher sintered density and lower porosity than MLC structured device. Also we can predict that they have an effect on good heat emission and high output properties of multilayer piezoelectric transformer.

• 대한수학회보
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• 제50권5호
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• pp.1441-1450
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• 2013

In this paper, we consider two-component Bose-Einstein condensates with an internal atomic Josephson junction in the general case, i.e., 0 < p < $\frac{2}{(d-2)^+}$. We prove existence and uniqueness results for the ground states, and obtain some properties of the ground states with large parameters.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1989년도 추계학술대회 논문집 학회본부
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• pp.388-392
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• 1989

In this paper, an adaptive pole-zero placement algorithm which has disturbance rejection properties is proposed. This method using the internal model principle is shown to reject the disturbances asymptotically. Furthermore, a method which reduces the number of estimated parameters is proposed. Some simulation results are given to demonstrate the performance of the algorithms.

• 한국산학기술학회:학술대회논문집
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• 한국산학기술학회 2001년도 춘계학술대회 발표논문집
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• pp.281-283
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• 2001

The low foamed high strengthen styrofoam samples made by dielectric heating are discussed. We used the oscillator which have the frequency of 13.6MHz and the Power of 7kW. 3 times expanded beads by steaming method were used in our foam-molding test. Internal fusion properties and density of internal structure were improved by dielectric foaming process. At the temperature of 105-110$^{\circ}C$, the internal fusion property was maximally improved.

• Structural Engineering and Mechanics
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• 제46권1호
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• pp.53-73
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• 2013

Prediction of prestressed concrete girder integral abutment bridge (IAB) load effect requires understanding of the inherent uncertainties as it relates to thermal loading, time-dependent effects, bridge material properties and soil properties. In addition, complex inelastic and hysteretic behavior must be considered over an extended, 75-year bridge life. The present study establishes IAB displacement and internal force statistics based on available material property and soil property statistical models and Monte Carlo simulations. Numerical models within the simulation were developed to evaluate the 75-year bridge displacements and internal forces based on 2D numerical models that were calibrated against four field monitored IABs. The considered input uncertainties include both resistance and load variables. Material variables are: (1) concrete elastic modulus; (2) backfill stiffness; and (3) lateral pile soil stiffness. Thermal, time dependent, and soil loading variables are: (1) superstructure temperature fluctuation; (2) superstructure concrete thermal expansion coefficient; (3) superstructure temperature gradient; (4) concrete creep and shrinkage; (5) bridge construction timeline; and (6) backfill pressure on backwall and abutment. IAB displacement and internal force statistics were established for: (1) bridge axial force; (2) bridge bending moment; (3) pile lateral force; (4) pile moment; (5) pile head/abutment displacement; (6) compressive stress at the top fiber at the mid-span of the exterior span; and (7) tensile stress at the bottom fiber at the mid-span of the exterior span. These established IAB displacement and internal force statistics provide a basis for future reliability-based design criteria development.

• 펄프종이기술
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• 제31권1호
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• pp.46-51
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• 1999

The most important effect of refining is believed as the internal fibrillation. The internal fibrillation is the separation of the fiber wall into several lamellae. The internal fibrillation results in fiber swelling as water penetrates the fiber wall. The increase in paper strength as a result of refining was due to delamination which made the fiber more flexible. Pulp fibers are refined to 20, 40, and 70$^{\circ}$SR freeness at Valley beater. Changes of Physical paper properties are analyzed depending on fiber wall thickness and fiber's collapse index at 2.5 and 5.6kg$_f$ refining load. At same $^[\circ}$SR freeness with 2.5kg$_f$ refining load, fiber wall thickness is increased further than at high 5.6kg$_f$ refining load. With higher fiber wall thickness by lower intensity refining load, higher internal fibrillation, flexibility, collapsability of fibers are achieved. Those effects improve WRV, tensile strength, and burst strength. Tear strength shows opposite trend to tensile and burst strength as usual.

• 공업화학
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• 제20권6호
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• pp.700-704
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• 2009

본 연구에서는 다공성 탄소전극의 내부 전해질 농도에 따른 전극의 전기화학적 특성 변화를 연구하였다. 다공성 탄소전극의 내부를 0.01, 0.05, 0.1, 0.5 M KCl 용액으로 채우고 양이온교환막을 결합한 후 cyclic voltammetry, chronoamperometry, impedance spectroscopy 분석을 실시하였다. 실험결과 전극의 특성은 전극 내부의 전해질 농도에 따라 큰 차이를 보였으며 농도가 높을수록 전극 내부의 charging 저항이 감소하여 전기용량이 크게 증가하는 것을 알 수 있었다. 실험결과로부터 이온교환막을 결합한 축전식 탈염공정에서 전극 내부의 전해질 농도를 높임으로써 저 농도의 염수를 효과적으로 탈염할 수 있을 것으로 기대된다.

• Bulletin of the Korean Chemical Society
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• 제30권9호
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• pp.2071-2076
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• 2009

The single-walled carbon nanotubes (SWCNTs) produced by chemical vapor deposition (CVD) were directly fluorinated with fluorine ($F_2$) gas in a temperature range 20 ~ 400 ${^{\circ}C}$. The surface properties and morphology of the SWCNTs were investigated in terms of fluorination temperature. As a result, Raman spectra showed a pair of bands at 1340 and 1590 $cm^{-1}$ peculiar to disordered $sp^2$-carbons. These results indicated that C-F bonds were formed on the rear surfaces of the nanotubes by fluorination, while the external surfaces as well as the layers between the internal and external surfaces retained their $sp^2$-hybridization. XPS analysis exhibited that fluorine atoms were bonded to carbon atoms on internal surfaces (rear surfaces) of the nanotubes and the amount of fluorine attached on the nanotubes was increased with increasing the fluorination temperature. Consequently, the direct fluorination of carbon nanotubes led to functionalization and modification of pristine nanotubes with respect to surface and morphological properties.

• 한국전기전자재료학회논문지
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• 제21권6호
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• pp.524-529
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• 2008

In this paper, in order to develop low loss multilayer actuator, piezoelectric properties of PZW-PMN-PZT multilayer actuator sintered at $900^{\circ}C$ low temperature were investigated according to the number of multilayer. The multilayer actuator was fabricated using tape casting method and used pure Ag internal electrode. The density above $8.0\;g/cm^3$ was obtained at all specimens. With increasing number of multilayer, effective electromechanical coupling factor($k_{eff}$) was increased. $k_{eff}$ of multilayer actuator shows the maximum value of 0.283 at 11 layers actuator. However, effective mechanical quality factor(Qm') was decreased according to the increase of number of multilayer. The Qm' of multilayer actuator showed the maximum value of 920 at 5 layers actuator.