• Proceedings of the KIEE Conference
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• 1996.07c
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• pp.1974-1976
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• 1996

An electrostatically driven comb actuator with $525{\mu}m$ height was fabricated using (110) Si anisotropic etching in the Potassium Hydroxide(KOH) solution. The etch-rate and etch-rate ratio are strongly dependent on the weight % and temperature of KOH solution. We developed the optimal condition for the anisotropic etching on (110) wafer with varying these conditions. The force that the comb-drive actuator generates is inversely proportional to the distance of gap and proportional to the height of the comb electrodes. The electrodes must have the high aspect ratio. The (110) Si anisotropic etching is very useful to get a high aspect ratio structure.

• Journal of Mechanical Science and Technology
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• v.18 no.5
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• pp.753-761
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• 2004

In this paper, an efficient method for generating 5-axis cutting data for a turbine blade is presented. The interference elimination of 5-axis cutting currently is very complicated, and it takes up a lot of time. The proposed method can generate an interference-free tool path, within an allowance range. Generating the cutting data just point to the cutting process and using it to obtain NC data by calculating the feed rate, allows us to maintain the proper feed rate of the 5-axis machine. This paper includes the algorithms for: (1) CL data generation by detecting an interference-free heel angle, (2) finding the optimal tool path interval considering the cusp-height, (3) finding the adaptive feed rate values for each cutter path, and (4) the inverse kinematics depending on the structure of the 5-axis machine, for generating the NC data.

• Korean Journal of Computational Design and Engineering
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• v.4 no.4
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• pp.355-359
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• 1999

This paper presents a method for determining machining parameters in electrical discharge machining process (EDM) based on discharge area. The parameters are the peak value of currents, the pulse-on time, and the pulse-off time, on which the EDM performance depends chiefly. The optimal machining parameters are closely related on discharge area, which can be calculated from a tool electrode and a discharge height. In the paper the discharge area is obtained from NC code for machining the tool electrode instead of its geometric model. The method consists of following three steps. First a Z-Map model is constructed from the NC code. Secondly, the discharge area is obtained from the Z-Map model and a Z-height. Finally, the machining parameters are calculated from the discharge area. An introduced example shows that the machining parameters are calculated by the using a Z-map model obtained from the machining data for a tool electrode.

• Transactions of Materials Processing
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• v.9 no.4
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• pp.339-347
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• 2000

For the successful forming of tailored blank, it is important to control the deformation of the stretch flange mode, which is strong1y dependent upon the location of weld line and blank shape. In order to investigate the effects of tailored blank design factors on the stretch flange forming, we made the model die which can simulate stretch flange mode. Taguchi method was employed to analyze the sensitivity of blank design factors for the forming of tailored blank. From the results of experiment S/N ratios were calculated and using Variance Analysis, significance of parameters and optimal condition of each factors were extracted. Based on these analyses, the weld line height and the strength ratio and the arc center height were selected as effective parameter. The analysed result was practically applied for Side outer panel stamping process.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2002.10a
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• pp.1041-1044
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• 2002

Inchworm linear motor is one of the ultra precision position apparatuses and has many kinds of forms and structures according to the conditions of working space and range. In this paper, the Inchworm linear motor consists of three PZTs(Piezo-electric transducer), three columns ma two plates. finite element method was used to determine the type or hinges installed in column of inchworm linear motor DOE(Design of experiment) was used to determine the optimal design condition of a column by comparing the von-mises stresses according to the change of thickness of hinge, round of hinge, height of arm, angle of v-notch, round of v-notch and thickness of column. From the result, round of hinge, height of arm and thickness of hinge were determined a effective design parameters.

• Journal of Environmental Science International
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• v.8 no.1
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• pp.95-100
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• 1999

Process intensification without any increase in bed requires the exploitation of fluid mechanical phenomena as the basis for elegant solutions to the process engineering problems which result from the need to retain and control the immobilized biomass, and for biomass recovery. The fluidized bed biological reactor provides a solution to these needs. The wastewater treatment characteristics of the fluidized bed was filled with sand media. Indirect aeration were studied experimentally. The researcher was filled with sand particle size(0.60~0.42mm) in three reactors with different section area(A)/height(H), in the state BOD loading 4.5kg-$BOD_5/m^3$ㆍd, and under the fixed state of hydraulic retention time for around 32 minutes.

• IE interfaces
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• v.20 no.4
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• pp.539-546
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• 2007

This study has been conducted on touch screen interface design for mobile devices. It was intended to measure user’s satisfaction on one-handed thumb input mobile devices. Recent studies proposed the optimal touch button size, but it is inappropriate for mobile devices. Therefore, this study was focused on four touch key factors-width, height, the horizontal and vertical distance between touch keys-as independent variables. The ANOVA results showed that the user satisfaction of four touch key factors was significantly affected by the thumb input. It also apparent that the interactions between four factors were significant. As a result, the horizontal and vertical distance as well as the width and height affected the satisfaction of users. In addition, this study suggested satisfaction models which represent the top 30%, 50%, 70% of user satisfaction measurement. The results of this study could be used to design touch keys that are able to enhance the usability on touch screen based mobile devices.

• KIEAE Journal
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• v.7 no.5
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• pp.41-46
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• 2007

The lightshelf system, a horizontal shading and light redirect device, should improve the visual environment by optimal light distributions and intense illumination levels of a interior. This study aims to evaluate the daylighting performance of window integrated lightshelf systems by computer simulations. For the study, the standard office plan is analyzed through the field surveys. And then, the various lightshelf types attached window systems are picked out from existed research results. The max, minimum and average illuminance levels of interiors and illuminance distributions are evaluated by Lightsacpe 3.2 programs based on the installing height, shape type and moving angle of lightshelfs. As results, it is suggested that the optimum lightshelf shapes are the height 1.8m and the width 600mm. Also, in mixed lightshelf, the outside width 600mm, inside width 400 are efficient on indoor daylighting performance.

• Journal of the Korean Society of Physical Medicine
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• v.19 no.1
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• pp.53-60
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• 2024

PURPOSE: The study aimed to analyze the effect of pillow height on upper trapezius and sternocleidomastoid (SCM) muscle activity and overall human body comfort to determine the optimal pillow height. METHODS: The study included 32 healthy college students, of both genders, who provided prior consent. It examined three pillow heights (flat, 6cm, 12cm) and measured the upper trapezius and SCM muscles using ultrasonography, myotone, and electromyography(EMG). Muscle activation, thickness, and fatigue were assessed. RESULTS: The study found significant differences in muscle thickness and muscle tone based on the pillow heights (flat, 6cm, and 12cm) with a p < .05. The SCM and upper trapezius muscles were thinnest at a pillow height of 6cm. Muscle tone in the SCM was lower at both 6cm and 12cm pillow heights. Post-hoc measurements showed significant differences in both the SCM and upper trapezius muscles thickness at the 6cm pillow height (p < .05). Also, significant differences in muscle tone were observed only in the SCM, particularly between the 6cm and 12cm pillow heights. CONCLUSION: The ultrasonography and myotone measurements showed a significant difference in muscle thickness and muscle tension, both of which were above 6cm, while there was no difference in muscle activation. Based on the strong correlation between muscle tension and muscle thickness with pillow height, this study concluded that the human body feels comfortable with a 6cm pillow height. Therefore, it is recommended to use a pillow height of 6cm when lying in a supine position.

• Clinics in Orthopedic Surgery
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• v.10 no.4
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• pp.407-412
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• 2018

Background: We conducted this study to determine the optimal length of patellar and tibial bone blocks for the modified transtibial (TT) technique in anterior cruciate ligament (ACL) reconstruction using the bone-patellar tendon-bone (BPTB) graft. Methods: The current single-center, retrospective study was conducted in a total of 64 patients with an ACL tear who underwent surgery at our medical institution between March 2015 and February 2016. After harvesting the BPTB graft, we measured its length and that of the patellar tendon, patellar bone block, and tibial bone block using the arthroscopic ruler and double-checked measurements using a length gauge. Outcome measures included the length of tibial and femoral tunnels, inter-tunnel distance, length of the BPTB graft, patellar tendon, patellar bone block, and tibial bone block and graft-tunnel length mismatch. The total length of tunnels was defined as the sum of the length of the tibial tunnel, inter-tunnel distance and length of the femoral tunnel. Furthermore, the optimal length of the bone block was calculated as (the total length of tunnels - the length of the patellar tendon) / 2. We analyzed correlations of outcome measures with the height and body mass index of the patients. Results: There were 44 males (68.7%) and 20 females (31.3%) with a mean age of 31.8 years (range, 17 to 65 years). ACL reconstruction was performed on the left knee in 34 patients (53%) and on the right knee in 30 patients (47%). The optimal length of bone block was 21.7 mm (range, 19.5 to 23.5 mm). When the length of femoral tunnel was assumed as 25 mm and 30 mm, the optimal length of bone block was calculated as 19.6 mm (range, 17 to 21.5 mm) and 22.1 mm (range, 19.5 to 24 mm), respectively. On linear regression analysis, patients' height had a significant correlation with the length of tibial tunnel (p = 0.003), inter-tunnel distance (p = 0.014), and length of patellar tendon (p < 0.001). Conclusions: Our results indicate that it would be mandatory to determine the optimal length of tibial tunnel in the modified TT technique for ACL reconstruction using the BPTB graft. Further large-scale, multi-center studies are warranted to establish our results.