• Bulletin of the Korean Chemical Society
• /
• 제18권7호
• /
• pp.720-729
• /
• 1997

The interface between two different polymers is characterized theoretically by using a model. This model is based on the assumption that the monomeric friction coefficients of the two polymers are identical but a strong function of the matrix composition. This model predicts that the concentration profiles are highly asymmetric with substantial swelling of the slower-diffusing component by the faster component. To predict the behavior of interdiffusion, three quantities are used: distance of interface Z*(t) due to the swelling, interfacial width W(t) which is most sensitive to the detailed composition profiling, and mass transport M(t) due to interdiffusion. It is found that the more dissimilar polymer pairs, the faster the movement of the interface, the quicker its interfacial width saturates to a limiting value and the slower its mass transport. These results are in qualitative agreement with some experiments.

• Geomechanics and Engineering
• /
• 제33권4호
• /
• pp.393-400
• /
• 2023

Displacements near crack and stress intensity factor (SIF) are key parameters to solve rock failure issue when using fracture mechanics. In order to study the horizontal displacement and stress intensity factor of the mode I fracture, a series of three-point bending tests of granite specimens with central notch were carried out. The evolution of horizontal displacements of precast notch and crack tip opening displacements (CTOD) were analyzed based on the digital image correlation (DIC) method. Stress intensity factors for three-point bending beams with arbitrary span-to-width ratios(S/W) were calculated by using the WU-Carlsson analytical weight function for edge-crack finite width plate and the analytical solution of un-cracked stress by Filon. The present study provides a high efficient and accurate method for fracture mechanics analysis of the three-point bending granite beams.

• 한국정밀공학회지
• /
• 제14권5호
• /
• pp.150-156
• /
• 1997

Three dimensional finite element analysis was conducted to estimate the effect of shape parameters (plate width and thickness) on the stress intensity factor for crack in the integrally stiffened plate. Analysis was done for width ratios of 0.5, 0.75, 1.0, 1.5, 2.0, 2.5, and thickness ratios of 2, 3, 4, 6. Based on these results, an empirical equation of geometry factor is formulated as a function of crack length and thickness ratio.

• 대한의용생체공학회:학술대회논문집
• /
• 대한의용생체공학회 1992년도 춘계학술대회
• /
• pp.203-208
• /
• 1992

In order to restore the gait function by functional electrical stimulation(FES) in hemiplegic patients, an electrical stimulator and foot sensor were developed on the basis of optimal parameters which resulted from animal experiments. Physical properties of the soleus muscle were quite different from those of themedial gastrocnemius muscle, that is, the former had a characteristic or slow muscle and the letter had a characteristic of fast muscle in rats. Optimal parameters for electrical stimulation were 0.2ms of pulse width and 20Hz of frequency in the soleus muscle and 0.3ms, 40Hz in the medial gastrocnemius muscle. Amplitude modulated electrical stimulator with -15V of maximal output was made and automatic on-off time if the stimulator was 5 seconds. The foot sensor composed of 3 sensors in 3 pressure points of the foot was made in order to control the gai t function by closed loop feedback system. The gait function was improved by using the stimulator and foot sensor in peroneal palsy. These results suggest that the electrical stimulator with closed loop feedback system may restore the gait function in hemiplegic patients.

• 제어로봇시스템학회논문지
• /
• 제17권8호
• /
• pp.731-738
• /
• 2011

In this paper, we introduce an advanced architecture of K-Means clustering-based polynomial Radial Basis Function Neural Networks (p-RBFNNs) designed with the aid of SSOA (Space Search Optimization Algorithm) and develop a comprehensive design methodology supporting their construction. In order to design the optimized p-RBFNNs, a center value of each receptive field is determined by running the K-Means clustering algorithm and then the center value and the width of the corresponding receptive field are optimized through SSOA. The connections (weights) of the proposed p-RBFNNs are of functional character and are realized by considering three types of polynomials. In addition, a WLSE (Weighted Least Square Estimation) is used to estimate the coefficients of polynomials (serving as functional connections of the network) of each node from output node. Therefore, a local learning capability and an interpretability of the proposed model are improved. The proposed model is illustrated with the use of nonlinear function, NOx called Machine Learning dataset. A comparative analysis reveals that the proposed model exhibits higher accuracy and superb predictive capability in comparison to some previous models available in the literature.

• 한국운동역학회지
• /
• 제34권3호
• /
• pp.125-132
• /
• 2024

Objective: The purpose of this research was to analyze the effects of applying functional electrical stimulation (FES) on function of the ankle joint and gait ability of the elderly. Method: In this research, 12 male participants over 65 who have no musculoskeletal disorder were recruited as research subjects. For this research, in order to analyze the function of the ankle joint and gait ability of the elderly depending on the application of FES, all subjects were tested WF (with FES) and WOF (without FES) in random order and 72-hour of resting was assigned between the conditions. For WF condition, 30-minute of FES treatment (frequency 90 Hz, pulse width 400 ㎲, on-off ratio 1:1) on ankle joint basal flexor muscle was implemented, and afterwards, Isokinetic muscle function on the ankle joint and gait ability were conducted for each condition. Results: The result showed that the maximum strength of ankle joint basal flexion motion WF statistically significantly increased compared to WOF. The single support ratio of gait motion WF statistically significantly decreased compared to that WOF. Conclusion: Thus, applying FES is considered to mitigate the functional decline of basal flexor of the elderly, and furthermore, it is considered to have positive effect on improvement of gait ability.

• 복식
• /
• 제28권
• /
• pp.99-112
• /
• 1996

In this study I purpose a new approach to the study of Korean costume history which includes a statistical method used in the prac-tical measurement of excavated Po's and the analysis of their quantitative changes. In the framework used in this study I de-pend on the nineteen variables picked out from the typological and chronological analysis of excavated clothes. The interrelationship of the variables as well as the standard of each part and its deviation in other forms are may main concern. Other methods are also very useful in my thesis: Correlation analysis Regression analysis Discrimination analysis Cluster analysis Discrimination analysis Cluster analysis Factor analysis One way analysis of variance. The findings of my study can be summarized as follows: 1. Every type of po has a general tendency to have more broadened sleeves while it does not show any considerable changes in the total length and in the width of armholes. 2. In the Correlation analysis each part of Po's is handled separately accordign to its chronology and type. The Regreesion analysis makes it possible to provide the sizes of miss-ing parts in excavated clothes and the numeri-cal value of each part needed in the pattern making. 3. The Discrimination analysis of the Po's whose types are unknown leads to the con-clusion that Chongsam and Chikryong Po are classified into Chikryong Po whereas Hongui is classified into Jooui In addition I propose discriminational function by which the age classification is possible discovering the variables associated with time change. 4. Five items-Gerneral Park's clothes Taewongun's clothes and three others produced later for the purpose of preserving Korean costume are proved to be in a differ-ent group and hence analyzed separately in the visual grouping of changui which is done after the cluster analysis and the factor analysis. 5. The results of the one way analysis of variance reveal that there is a difference in each part from period: the back width the sleeve length the sleeve width thelean fig-ure the breasttie length the breasttie width outside quesset upper inside quesset lower outside neckband length insideneckband length etc.

• 한국전자파학회논문지
• /
• 제26권5호
• /
• pp.445-454
• /
• 2015

본 논문에서는 고이득 이중 반사경 안테나(DTA: Dual Reflector Antenna)의 성능 향상을 위한 최적설계 기법으로 유전 알고리즘(GA: Genetic Algorithm)을 적용하였다. 또한, 최적설계과정에서 반복해석에 요구되는 계산 시간을 줄이고자 ADE 안테나의 각 반사경의 표면전류분포 계산에 반복적 물리광학법(IPO: Iterative Physical Optics)을 이용하였다. 물리광학법 적용시 음영지역에 대한 고려 및 다중반사에 의한 영향을 MFIE(Magnetic Field Integral Equation) 기반의 반복적인 계산을 통해서 해의 정확도를 향상시켰다. 또한, 설계변수의 축소 및 제작 가능한 부드러운 곡면 형성을 위하여 베지어 곡선을 적용하였다. 이럴 경우, 베지어 곡선의 제어점이 설계변수로 설정이 된다. 최적설계를 위한 목적함수로 HPBW(Half Power Beam Width), FNBW(First Null Beam Width), SLL(Side Lobe Level) 등을 고려하였으며, 설계 및 해석의 결과를 기존의 상용 해석프로그램과 비교하였다.

• The Journal of Advanced Prosthodontics
• /
• 제1권3호
• /
• pp.140-144
• /
• 2009

STATEMENT OF PROBLEM. Little information is available about the buccal gingival level of multiple implant restorations. PURPOSE. This study was aimed to evaluate the relationship between width and height of buccal soft tissue around single and 2 adjacent implant restorations. MATERIAL AND METHODS. Four implant restoration groups (first and second molars, single second molars, posterior single restorations between teeth, and anterior single restorations between teeth) were randomly chosen from one dental institute. Each group comprised of 6 patients. After 6 months of function, silicone impressions were taken and stone models were fabricated for each restoration group. The stone models were cut in bucco-lingual direction at the most apical point of buccal gingival margin. The height and width of buccal supra-implant soft tissue were measured. One way ANOVA and Tukey HSD post hoc tests were performed to analyze the data obtained (P < .05). RESULTS. The most unfavorable width-height ratio was noted for the group, which was comprised of the second molar in the multiple adjacent (first and second molar) implant-supported restorations. The group also resulted in the shorter height of buccal supra-implant mucosa rather than that of anterior single implant restorations between natural teeth. CONCLUSION. To achieve a favorable level of buccal gingival margin, greater thickness of buccal supra-implant mucosa is required for the implant restorations without a neighboring natural tooth compared to the implant restorations next to a natural tooth.

• 정보저장시스템학회논문집
• /
• 제1권2호
• /
• pp.150-154
• /
• 2005

The effects of track format on the inter-track crosstalk of holographic ROM system are investigated. To quantify the effect of inter-track crosstalk for various track width and pitch, we defined Signal to Crosstalk noise Ratio(SCR) as a criterion. A numerical simulation is used to obtain the SCR as a function of track widths and pitches. We compared different 4 track widths having 0.3, 0.4, 0.5, and 0.6 ${\mu}m$ considering resolving power of lens and recording density. The simulation results show that the SCRs for each track width are maximized at the track pitch which has the value of 0.72, 0.72, 0.74, and 0.5 ${\mu}m$ respectively. Next, for the three sets with track width-pitch(0.4-0.72, 0.5-0.74, 0.6-0.8 ${\mu}m$) which showed the maximum SCR, we set a minimum pit length so that all sets have a DVD equivalent data density and compared RF signals passed from the slit. The simulation results show that when the track width, pitch, and minimum pit length have 0.5, 0.74, and 0.4 ${\mu}m$ respectively, the difference between the maximum and minimum value of the RF signal showed the greatest value. Also, we investigated RF signal in case of using an amplitude inversion mask, which transmitted regions are inversed against the conventional mask. The simulation results show that the better RF signal may be obtained by using an amplitude inversion mask.