• 전자공학회논문지SC
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• 제45권1호
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• pp.50-56
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• 2008

본 논문에서는 롤(Roll)에 누워 있는 피검자의 각도와 가속도 신호를 측정하기 위한 디지털 경사계 설계하였다. 개발된 시스템은 기울기 센서(tilt sensor), 2축 가속도 센서(biaxial accelerometer), 마이크로프로세서(single chip microprocessor)와 블루투스(BlueTooth module)로 구성된다. 개발된 디지털 시스템은 다루기 쉽고 쉽게 착용 할 수 있다. 시스템을 성능을 평가하기 위해서 Roll위의 3명의 피검자로부터 각도와 가속도 신호는 ZEBRIS와 디지털 경사계에 의해서 동기화하여 측정하였다. 측정된 신호는 정량적인 방법에 의해서 처리되며 그때의 상관계수가 0.93임을 보여 준다. 이와 같은 결과로부터 디지털 경사계는 몸의 움직임을 평가하는데 유용할 것으로 보여 진다.

• 한국의류산업학회지
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• 제6권5호
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• pp.605-612
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• 2004

This is a study which evaluates the brand personality on casual brands according to the sensibilities of consumers. Focus is placed on classifying the sensibilities of consumers through G sensibilities developed by the Fuji Research Institute in Japan, and then on investigating brand personality of casual wear, Levi's in particular. The subjects are 187 male and female college students living in the Busan area. Data were, using SPSS 10. 0 for Window, statistically analyzed by frequency and factor analysis for VARIMAX, Cronbach's coefficient, and ANOVA. The results of data analysis are as follow; First, in the distribution of G sensibility type, the majority of the respondents have G3(whimsical) type, and then followed by G1(my pace) type, G4(active) type, G2 type(active) type and then G5(sensualist) type. Second, as a result of brand personality evaluation on the casual brands, it has been represented by the following 5 factors; passion, competence, honesty, sophistication, and sentiment. Third, the brand personalities according to G sensibilities showed significant differences among respondents; G5 type(sensualist) especially showed the highest brand personality in the passion and sentiment factors, which are distinctive in the brand personality of Levi's. Consumers of G1 type, G2 type, G3 type, and G4 type showed high brand personality in the competence and honesty factors. The evaluation of brand personality, case study for products development and application, and application of the results need to be continued for follow-up study.

• 한국재료학회지
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• 제27권3호
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• pp.132-136
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• 2017

We synthesized potassium hexatitanate, ($K_2Ti_6O_{13}$, PT6), with a non-fibrous shape, by acid leaching and subsequent thermal treatment of potassium tetratitanate ($K_2Ti_4O_9$, PT4), with layered crystal structure. By controlling nucleation and growth of PT4 crystals, we obtained splinter-type crystals of PT6 with increased width and reduced thickness. The optimal holding temperature for the layered PT4 was found to be ${\sim}920^{\circ}C$. The length and width of the PT4 crystals were increased when the nucleation and growth time were increased. After a proton exchange reaction using aqueous 0.3 M HCl solution, and subsequent heat treatment at $850^{\circ}C$, the PT4 crystal transformed into splinter-type PT6 crystals. The frictional characteristics of the friction materials show that as the particle size of PT6 increases, the coefficient of friction (COF) and wear amounts of both the friction materials and counter disc increase.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2011년도 제40회 동계학술대회 초록집
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• pp.335-335
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• 2011

Instability of a thin film attached to a compliant substrate often leads to emergence of exquisite wrinkle patterns with length scales that depend on the system geometry and applied stresses. However, the patterns that are created using the current techniques in polymer surface engineering, generally have low aspect ratio of undulation amplitude to wavelength, thus, limiting their application. Here, we present a novel and effective method that enables us to create wrinkles with a desired wavelength and high aspect ratio of amplitude over wavelength as large as to 2.5:1. First, we create buckle patterns with high aspect ratio of amplitude to wavelength by deposition of an amorphous carbon film on a surface of a soft polymer poly(dimethylsiloxane) (PDMS). Amorphous carbon films are used as a protective layer in structural systems and biomedical components, due to their low friction coefficient, strong wear resistance against, and high elastic modulus and hardness. The deposited carbon layer is generally under high residual compressive stresses (~1 GPa), making it susceptible to buckle delamination on a hard substrate (e.g. silicon or glass) and to wrinkle on a flexible or soft substrate. Then, we employ glancing angle deposition (GLAD) for deposition of a high aspect ratio patterns with amorphous carbon coating on a PDMS surface. Using this method, pattern amplitudes of several nm to submicron size can be achieved by varying the carbon deposition time, allowing us to harness patterned polymers substrates for variety of application. Specifically, we demonstrate a potential application of the high aspect wrinkles for changing the surface structures with low surface energy materials of amorphous carbon coatings, increasing the water wettability.

• 한국자동차공학회논문집
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• 제24권6호
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• pp.684-693
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• 2016

The luxury car industry has grown 10.5 % every year from 2010 to 2014. For this reason, it is very important for automotive companies to improve profitability and brand value. High-performance brake systems have become an absolute necessity because of the increase in engine power and customer preference among other factors. Also, competing automotive companies actively reinforce domestic production in order to maintain quality and infrastructure for luxury cars. In this regard, we demonstrated new carbon ceramic brakes to improve brake reliability for luxury cars and to improve the competitiveness of automotive companies. Finally, we propose the next-generation braking technology by predicting technological evolution trends.

• 열처리공학회지
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• 제24권3호
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• pp.127-132
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• 2011

The silicon-containing Diamond-like Carbon (Si-DLC) film as an low friction coefficient coating has especially treated a different silicon content by plasma-enhanced chemical vapor deposition (PECVD) process at $500^{\circ}C$ on nitrided-STD 11 mold steel with (TMS) gas flow rate. The effects of variable silicon content on the Si-DLC films were tested with relative humidity of 5, 30 and 85% using a ball-on-disk tribometer. The wear-tested and original surface of Si-DLC films were analysed for an understanding of physical and chemical characterization, including a changing structure, via Raman spectra and nano hardness test. The results of Raman spectra have inferred a changing intra-structure from dangling bonds. And high silicon containing DLC films have shown increasing carbon peak ratio ($I_D/I_G$) values and G-peak values. In particular, the tribological tested surface of Si-DLC was shown the increasing hardness value in proportional to TMS gas flow rate. Therefore, at same time, the structure of the Si-DLC film was changed to a different intra-structure and increased hardness film with mechanical shear force and chemical reaction.

• 대한가정학회지
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• 제39권12호
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• pp.253-269
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• 2001

The goal of this study is to examine the level of disposition conformity in everyday life and behavior conformity in clothes brand choice, and analyze the effects of disposition conformity and influential variables on behavior conformity in brand choice. For this analysis, the data were collected from 478 middle school and high school students in Seoul through surveys. Frequency, percentage, mean, standard deviation, Pearson's correlation coefficient, ANOVA, t-test, Duncan's multiple range test and multiple regression have been used to analyze the research objectives. Main findings are following; First, the 62.8% of the students showed high level of disposition conformity, and the 60.7% of them showed relatively low level of behavior conformity in brand choice. The adolescent consumers'disposition conformity to the reference groups in everyday life is in the order of parents, peer group, and mass media star. Second, the group differences in disposition conformity are diversified by independent variables. Among socio-demographic variables, disposition conformity to peer group differ by grade and disposition conformity to parents differ by the parents'education. Sex causes differences between groups in all disposition conformity except parents. In economic variables, the perceived level of living raises differences between groups in disposition conformity to the parent and whole disposition conformity. As the degree of disposable money gets higher in buying clothes, adolescent consumers conform more to the mass media star. Disposition conformity to parents and peer group were also differed by self-esteem. Third, significant variables, which affect the adolescent consumers'behavior conformity in brand choice, are grade, their mother's education, degree of disposable money in buying clothes, and disposition conformity to peer group and mass media star.

• Transactions on Electrical and Electronic Materials
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• 제8권2호
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• pp.67-72
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• 2007

High Pressure Micro Jet (HPMJ) pad conditioning system was investigated as an alternative to diamond disc conditioning in copper CMP. A series of comparative 50-wafer marathon runs were conducted at constant wafer pressure and sliding velocity using Rohm & Haas IC1000 and Asahi-Kasei EMD Corporation (UNIPAD) concentrically grooved pads under ex-situ diamond conditioning or HPMJ conditioning. SEM images indicated that fibrous surface was restored using UNIPAD pads under both diamond and HPMJ conditioning. With IC1000 pads, asperities on the surface were significantly collapsed. This was believed to be due to differences in pad wear rates for the two conditioning methods. COF and removal rate were stable from wafer to wafer using both diamond and HPMJ conditioning when UNIPAD pads were used. Also, HPMJ conditioning showed higher COF and removal rate when compared to diamond conditioning for UNIPAD. On the other hand, COF and removal rates for IC1000 pads decreased significantly under HPMJ conditioning. Regardless of pad conditioning method adopted and the type of pad used, linear correlation was observed between temperature and COF, and removal rate and COF.

• Nuclear Engineering and Technology
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• 제46권5호
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• pp.633-640
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• 2014

In this research, the surface roughness affecting the pressure drop in a pipe used as the steam generator of a PWR was studied. Based on the CFD (Computational Fluid Dynamics) technique using a commercial code named ANSYS-FLUENT, a straight pipe was modeled to obtain the Darcy frictional coefficient, changed with a range of various surface roughness ratios as well as Reynolds numbers. The result is validated by the comparison with a Moody chart to set the appropriate size of grids at the wall for the correct consideration of surface roughness. The pressure drop in a full-scale U-shaped pipe is measured with the same code, correlated with the surface roughness ratio. In the next stage, we studied a reduced scale model of a U-shaped heat pipe with experiment and analysis of the investigation into fluid-structure interaction (FSI). The material of the pipe was cut from the real heat pipe of a material named Inconel 690 alloy, now used in steam generators. The accelerations at the fixed stations on the outer surface of the pipe model are measured in the series of time history, and Fourier transformed to the frequency domain. The natural frequency of three leading modes were traced from the FFT data, and compared with the result of a numerical analysis for unsteady, incompressible flow. The corresponding mode shapes and maximum displacement are obtained numerically from the FSI simulation with the coupling of the commercial codes, ANSYS-FLUENT and TRANSIENT_STRUCTURAL. The primary frequencies for the model system consist of three parts: structural vibration, BPF(blade pass frequency) of pump, and fluid-structure interaction.

• 한국재료학회지
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• 제20권8호
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• pp.444-449
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• 2010

Transparent ceramics are used in new technology because of their excellent mechanical properties over glasses. Transparent ceramics are nowadays widely used in armor, laser windows, and in high temperature applications. Silicon nitride ceramics have excellent mechanical properties and if transparent silicon nitride is fabricated, it can be widely used. h-BN has a lubricating property and is ductile. Therefore, adding h-BN to silicon nitride ceramics gives a lubricating property and is also machinable. Translucent silicon nitride was fabricated by hot-press sintering (HPS) and 57% transmittance was observed in the near infrared region. A higher wt. % of h-BN in silicon nitride ceramics does not favor transparency. The optical, mechanical, and tribological properties of BN dispersed polycrystalline $Si_3N_4$ ceramics were affected by the density, ${\alpha}:{\beta}$-phase ratio, and content of h-BN in sintered ceramics. The hot pressed samples were prepared from the mixture of $\alpha-Si_3N_4$, AlN, MgO, and h-BN at $1850^{\circ}C$. The composite contained from 0.25 to 2 wt. % BN powder with sintering aids (9% AlN + 3% MgO). A maximum transmittance of 57% was achieved for the 0.25 wt. % BN doped $Si_3N_4$ ceramics. Fracture toughness increased and wear volume and the friction coefficient decreased with an increase in BN content. The properties such as transmittance, density, hardness, and flexural strength decreased with an increase in content of h-BN in silicon nitride ceramics.