• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.16 no.7
• /
• pp.4381-4387
• /
• 2015

Ship hull is a compound curved shape and most of shipyards have been using gas heating method for the surface forming of steel plate. This traditional forming process have problems such as difficulties in heat input control and poor working conditions due to loud noise and air contamination. Recently, researches on automatic hull forming system have been conducted using high frequency induction heating method which have good control ability and favorable working environment. In this study, the induction heating simulation system for curved surface forming of steel plate was developed and induction heating experiments were performed. Based on the results of this study, efficient induction heating coil design and optimal heating conditions for the automatic hull forming system can be obtained.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.16 no.1
• /
• pp.429-437
• /
• 2015

The purpose of this study was to investigate physical activity level, sleep quality, attention control, and self-regulated learning along to smartphone addiction level among college students. The data were obtained from 269 college students by structured questionnaire, analyzed using SPSS 18.0. The results showed that significant differences with smartphone addictoin level and, gender, grade level, daily using time, physical activity level, sleep quality and attention control. Smartphone addictoin level have correlations with physical activity level, sleep quality, attention control, and self-regulated learning. To prevent the falling off of physical strength and poor school performance, it is needed a strategies for control of smartphone addiction.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.21 no.2
• /
• pp.280-286
• /
• 2020

Cards made from PVC and PET materials do not oxidize or decompose readily, so they are generally incinerated or landfilled after use and cause pollution problems, such as environmental hormones and combustion gases during incineration. In addition, there is a problem of environmental pollution because they are discarded as semi-permanent refuse without being decomposed at landfill. This study attempted to solve this problem using polylactic acid (PLA), which is a representative biodegradable material as a substitute material that can solve the issues with these cards. On the other hand, when the thin card core sheet is made from only PLA material, the physical properties of the material are insufficient, such as the low temperature impact strength, high temperature stability, and poor bending properties, so its use is limited. To solve this problem, the compositional ratio of PLA was reviewed, and the optimal biodegradable compound composition was determined through an examination of the compositions, such as crystallization nucleating agents, additives, and nano compound technology. The high functionalization as a biodegradable card was verified through a laminating process using annealing technology.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.19 no.1
• /
• pp.188-198
• /
• 2018

Since infants' skin is very weak and has poor adaptability to environment, they are vulnerable to dermatitis caused by chemicals. Organic cotton for baby wear with the same functions in inner and outer wears can be considered the most suitable fiber. Therefore, this study analyzes products and colors of Korean and U.S. baby wear brands which use organic cotton. Of the total of seven organic brands of baby wear examined in this study, three were Korean baby wear brands and four were U.S. brands. and design colors of total 331 items were examined on the web. The results of comparative analysis showed that there were more U.S. brands than Korean brands in designs by uses. Color analysis showed that Korean natural cotton color was preferred and Y, G colors are commonly used, but colors of U.S. brands featured increased variety compared with Korean brands. Therefore, the Korean infant and toddler brand using organic cotton requires more diverse designs and delicate and broad colors.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.12 no.6
• /
• pp.2859-2865
• /
• 2011

The welded connection is known as an essential factor for establishing qualified construction and/or maintenance of wrapped steel pipe. In this study, welded connection conditions in the coated pipes with large diameter (over 700 mm) in Korea water distribution systems were estimated for suggesting technically and economically available welded connection method. For the study analysis, current steel pipe usage and accident cases were investigated. In addition, the characteristics of each welded connection method and automatic or manual connection techniques were also compared and estimated. As results, automatic welded connection method is superior than manual welded connection method in aspect of pure construction cost (average 9%) or pure welded connection cost (average 13.5%). When the poor welding-working situations in Korea are considered such as high tolerance of out-of-roundness in KS regulation, a number of lap joint welded connections, the real cost benefits of automatic welded connection should be much higher than those of manual welded connections.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.11 no.8
• /
• pp.2860-2867
• /
• 2010

In this research, I tried to make a comparative study of ideological characteristics of Industrial Relations between Korea and U.K., based on the presupposition that ideologies of Industrial Relations' Actors played an important role in Industrial Relations. U.K. have a voluntary and pluralistic ideological tradition of Industrial Relations, therefore U.K. is very rational to adjust and integrate different ideologies of actors. Meanwhile Korea have unrealistic, exclusive and rigid ideologies, therefore these have played a important role in worsening labor-management conflicts. For example strikes frequencies and workers involved in strikes are relatively few, but Workdays Lost due to strikes are very severe because of long strike durations, compared to U.K. Consequently national economic loss due to strikes has been severe. Korea trade unions are various and poor, but at the same time not mutual understanding in ideologies. Therefore from the viewpoint that strength in U.K.'s Industrial Relations stands on the power of adjusting different ideologies, we have to diminish the disparities between ideologies and realities of Industrial Relations through public discussion.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.14 no.12
• /
• pp.6114-6118
• /
• 2013

This study examined the ultrasonic pulse reflection method(UPRM) for testing each ultrasonic pulse waveform model(UPWM) based on weld defects. The sharp crack of a clear signal was generated. The echo height of the defective probes changed according to the location. In a long crack in a circle around the defective probes, the Swivel scanning echo height when using the particle was reduced drastically. The peaks in the echo were thin because the needle was pointed. The porosity defects arising from a single echo was sharp and crisp, but a number of pores of the collective reflection overlapped and ajagged echo was observed. Slag, slag inclusions, cracks, and defects at the Swivel scan of each particle using the echo shape showed difference in the degree. Cracks were revealed as sudden changes in the echo height of the slag inclusions: increase ${\rightarrow}$ decrease ${\rightarrow}$ increase ${\rightarrow}$ decrease. In addition, the location of a number of defects in the dense pore geometry, such as a typical echo sundry, revealed the shape in the slag. Poor penetration of the defect echo, revealed the cracks to have a sharp-edged, crack-like shape with an echo.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.7 no.4
• /
• pp.743-748
• /
• 2006

We investigated the flame retardancy and the mechanical properties of Nylon6 by using melamine-based halogen-free flame retardants(melamine cyanurate:MC-100 and melamine phosphate:MP-100). We chose the UL-94 method for flame retardancy and measured the tensile strength, flexural strength, flexural modulus by using UTM and impact strength by using Izod impact tester. We also tested the effect of nano-clay on flammability and mechanical properties. We obtained the V0 grade when the concentration of flame retardant was over 5 wt%. The tensile strength and flexural strength decreased and flexural modulus increased with the concentration of both flame retardant systems. The results showed that MC-100 system was better than MPP-100 system. Because of poor dispersion, we did not obtain the synergistic effect of nano-clay.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.16 no.3
• /
• pp.1611-1619
• /
• 2015

This study examined the toughness improvement of a track shoe used as the undercarriage of excavator and bulldozer parts. The excavator is operated under poor conditions, such as the build-up field and quarry. Therefore, the track shoe requires high strength and impact toughness to endure immense shock while at work. The track shoe was made of heat treated boron steel. The sufficient possibility of hardenability with the theoretical Jominy curve for boron steel was confirmed while quenching. The Taguchi orthogonal array experiment method was used to optimize the process variables, such as area reduction ratio and heat treatment conditions (tempering temperature and holding time), to achieve toughness improvement. The toughness of the track shoe increased with increasing area reduction, and a tempering temperature of $210^{\circ}C$ and a tempering time of 80 min are beneficial for improving the toughness of the track shoe.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.16 no.3
• /
• pp.1692-1698
• /
• 2015

The purpose of this study is to examine the effects of family affluence on happiness and to investigate the mediating effects of self-rated health on the relationship between family affluence and happiness. This study was conducted to analyze the data which were derived from 8th(2012) of the online census on youth health behavior conducted by the Ministry of Disease Control and total subjects were 74,168. The result of this study is that social-economy is regarded as a little poor. On the other hand, subjective health is regarded as a good and they generally satisfied with life. The relationship between family affluence, happiness, and self-rated health, family affluence level is linked to happiness and self-rated health, and self-rated health has positive effects on the level of happiness. That is, it was verified that self-rated health has a partial mediation effect on the way that family affluence influences happiness. Based on the results of study, the followings are suggested: the impact of socioeconomic disparities on health disparities needed to be decreased; The efforts of the social dimension, health policy formulation and execution of multi-dimensional which is to increase happiness should be implemented.