• Journal of Digital Convergence
• /
• v.12 no.4
• /
• pp.293-303
• /
• 2014

The mobile game market is fast growing after the Kakao game launched. Especially, the market is placed at the second highest by occupying 33.1% of the market. However, the rate of the total sales amount is only 6%, showing quite an imbalance between the market occupancy and the sales amount. This means that the profit-making models are not stabilized yet in the mobile game market. The absence of profit-making models can be ascertained by the relationship of DAU and sales ranking. There are several games which are ranked at DAU Top10 among Google free games, but not ranked at top 10 among sales amounts. On the other hand, there are several games which are low in DAU ranking but high in sales amount ranking. This result shows that there is no direct interrelation between the product attractiveness which users feel and the profit-making models in the market. This study compared the Google play free games which are ranked at top 10 in terms of DAU ranking and sales amount ranking to find out the factor which causes the imbalance between the DAU ranking and sales amount ranking. Based on this outcome, this study presents the reference point for the design of profit-making models on behalf of the manufacturers who wish to launch into the mobile game market in the future.

• Journal of Life Science
• /
• v.28 no.4
• /
• pp.483-487
• /
• 2018

Cypermethrin, a commonly used domestic and agricultural pyrethroid pesticide, is widely considered detrimental to the environment and to many organisms because of its residual property and toxicity. Cellulophaga lytica DAU203, isolated from coastal sediment, was chosen because it degrade cypermethrin. Cellulophaga lytica DAU203 effectively degraded cypermethrin, as the utilized carbon source and substrate, in a mineral salt medium. Effective factors, such as carbon source, nitrogen source, initial pH, and temperature, for cypermethtin biological degradation by Cellulophaga lytica DAU203 were analyzed by one factor at a time method. Temperature ($22{\sim}42^{\circ}C$), initial pH (5~9), and yeast extract concentration (0.1~2.5%[w/v]) were selected as the three most important factors. There were optimized at $33.4^{\circ}C$, pH 7.7, and 2.4%(w/v) by response surface methodology, respectively. The Box- Behnken design consisting of 46 experimental runs with three replicates was used to optimize the independent variables which significantly influenced the cypermethrin biological degradation. This model for cypermethrin degradation by Cellulophaga lytica DAU203 is highly significant (p<0.05). Under the optimized condition, Cellulophaga lytica DAU203 degraded approximately 83.7 % of the cypermethrin within 5 days. These results suggest that Cellulophaga lytica DAU203 may be useful for the biological degradation of cypermethrin in cypermethrin-contaminated environments.

• Proceedings of the Korean Society of Precision Engineering Conference
• /
• 2005.06a
• /
• pp.1984-1987
• /
• 2005

This study evaluate the statical stability of the container crane with respect to the direction of wind load which is varied between $0^{\circ}$ and $180^{\circ}$ and its average velocity is 40m/s. Using wind experimental data and a formula of wind pressure, we figured out the wind load needed to perform a finite element analysis. And we can obtain the variation of reaction forces at each supporting point according to the direction of wind load.

• Proceedings of the Korean Society of Precision Engineering Conference
• /
• 2005.06a
• /
• pp.1605-1608
• /
• 2005

This study was carried out to analyze the effect of machinery house location on the stability of high efficiency gantry crane which can improve the productivity of the container transportation wok by reducing cycle time. The wind load was evaluated according to 'Load Criteria of Building Structures' enacted by the ministry of construction & transportation. The uplift forces of high efficiency gantry crane under this wind load were calculated by analyzing reaction forces at each supporting point. And variation of reaction forces at each supporting point was analyzed according to machinery house location.

• Proceedings of the Korean Society of Precision Engineering Conference
• /
• 2006.05a
• /
• pp.349-350
• /
• 2006

PAM-STAMP is a widely used program which deals with press forming analysis. A blanking used in the press process depends on the experience of the workers. Thus it causes some waste material and demands a lot of time and many costs at the manufacturing mold. So we need to optimize of the blanking size. We have studied the optimal blanking size of the Brace Center Pillar using an Inverse module in PAM-STAMP

• Proceedings of the Korean Society of Precision Engineering Conference
• /
• 2005.10a
• /
• pp.419-422
• /
• 2005

This study is an inspection of press forming product and mould using reverse engineering system. The inspection process on production field involves a lot of errors because of the hand-work so we focussed on improving the measured precision through performing the effective inspection using 3D non-contact scanner. By so doing that, we improved the precision of press forming product by analyzing the cause fellowing the inspection result. Through the inspection, we applied it to the reverse engineering and we could improve the inspection process.

• Proceedings of the Korean Society of Precision Engineering Conference
• /
• 2005.10a
• /
• pp.657-660
• /
• 2005

It is net easy to predict the shrinkage rate of a plastic injection mold in its design process. The shrinkage rate should be considered as one of the important performances to produce the reliable products. The shrinkage rate can be determined by suing the CAE tools in the design produces. However, since the analysis can take minutes to hours, the high computational costs of performing the analysis limit their use in design optimization. Therefore this study was carried out to presume for mutual relation of analysis condition to get the optimum average shrinkage by regression analysis. The results shown that coefficient of determination of regression equation has a fine reliability over 88.3% and regression equation of average shrinkage is made by regression analysis.

• Proceedings of the Korean Society of Precision Engineering Conference
• /
• 2005.10a
• /
• pp.962-965
• /
• 2005

This study is an inspection of press forming product and mould using reverse engineering system. The inspection process on production field involves a lot of errors because of the hand-work so we focussed on improving the measured precision through performing the effective inspection using 3D non-contact scanner. By so doing that, we improved the precision of press forming product by analyzing the cause following the inspection result. Through the inspection, we applied it to the reverse engineering and we could improve the inspection process.

• Proceedings of the Korean Society of Precision Engineering Conference
• /
• 2005.06a
• /
• pp.1626-1629
• /
• 2005

Recently many countries have concentrated their effort on the port automation, in order to be the Hub-port, that the Ultra Large Container Ship could come alongside the Quay, in their region. As the magnitude of the container ship increase, that of the Quay crane increases from 50ton-class to 61ton-class more and more. The wind speed criteria to design the structures used in the port was upgraded from 20m/s to 40m/s due to change of the weather condition. Our laboratory could have the ability to design the wedge type rail clamp for 50ton-class Quay crane in 30m/s wind speed. Accordingly we analyzed the load condition of the Quay crane about 40m/s wind speed upgraded from 20m/s and designed the wedge type rail clamp for 50ton and 61ton-class Quay crane.

• Proceedings of the Korean Society of Precision Engineering Conference
• /
• 2006.05a
• /
• pp.441-442
• /
• 2006

It is attempted to find out the optimal shape of U-type bellows using the finite element analysis. The design factors, mountain height, length, thickness, and the number of convolutions are considered and the proper values are chosen fur the simulation. The results show that as the number of convolutions reduces, the volume decreases while the stress increases. However, as the number of convolutions increases, the volume increases above the standard volume and the stress obviously increases. In addition, the effect of the thickness of bellows on the stress is very large. Both of the mass and stress are decreasing at a certain lower value region. Also, we investigated shape optimization with considering maximum stress distribution tendency.