• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2011.05a
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• pp.196-197
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• 2011

Rudder, one of the most important component in the marine vessel, is now being decreased life time to serve due to cavitation erosion, vortex current, high flow speed suffer from ship speed going up dramatically. In this study, 10 kinds of thermal spray coating materials(2 of Zn alloy series, 3 of Al alloy series, 3 of Cu alloy series, 2 of STS alloy series) are chosen to apply on specimens and analyze micro structure, metallic composition, properties(porosity, oxidation) by using visual observation, XRD, EDX etc.. Additionally, to refine the characteristic of corrosion endurance for thermal spray coating layer, compared with thermal spray process and 5 kinds of heavy duty painting and AC paint (Anti-Corrosion Paint). Based on above mentioned experimental results, a priority of all coated specimens on corrosion-erosion endurances finalized and summarized there by desirable composition and process of thermal sprayed material properly.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.27 no.8
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• pp.491-496
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• 2014

The resistive switching characteristics of resistive random access memory (ReRAM) based on amorphous $Ge_{0.5}Se_{0.5}$ thin films have been demonstrated by using Ti/Ag nanocrystals/$Ge_{0.5}Se_{0.5}$/Pt structure. Ag nanocrystals (Ag NCs) were spread on the amorphous $Ge_{0.5}Se_{0.5}$ thin film and they played the role of metal ions source. As a result, comparing the conventional Ag/$Ge_{0.5}Se_{0.5}$/Pt structure, this Ti/Ag NCs/$Ge_{0.5}Se_{0.5}$/Pt ReRAM device exhibits the highly uniform bipolar resistive switching (BRS) characteristics, such as the operating voltages, and the resistance values. At the same time, a stable DC endurance(> 100 cycles), and the excellent data retention (> $10^4$ sec) properties were found from the Ti/Ag NCs/$Ge_{0.5}Se_{0.5}$/Pt structured ReRAM device.

• Journal of the Korea Furniture Society
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• v.17 no.1
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• pp.23-32
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• 2006

This study was carried out to explore a new application of traditional Hanji and obtain fundamental properties for producing Hanji wallpaper by incorporating ceramics from wood and rice-husk as an interior building material. The results of properties determined were summarized as follows: The addition of ceramics in Hanji paper reduced its apparent density, but increased bulk density due to the ceramic particles distributed on the surface and inside the fiber of Hanji wallpapers. In particular, woodceramic particles were specifically distributed on the fiber surface, while particles of rice-husk ceramics were permeated into the inside surface of fibers. The density of rice-husk ceramics were greater than that of woodceramics. The physical properties of Hanji wallpapers, such as breaking strength, wet breaking strength, burst strength, tear index and folding endurance were deteriorated with the addition of ceramics. However, the addition of woodceramics in the Hanji wallpaper resulted in better strength in most cases than that of rice-husk ceramics, except tear strength. Therefore, an optimum addition level of woodceramics into the wallpaper was found to be 5% on the basis of intensity. The addition of ceramics also prolonged the combustion time because it lowered air permeability and brightness of the wallpaper.

• Proceedings of the Korean Vacuum Society Conference
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• 2010.02a
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• pp.233-233
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• 2010

Magnetic random access memory (MRAM), based on magnetic tunnel junction (MTJ) and CMOS, is a prominent candidate among prospective semiconductor memories because it can provide nonvolatility, fast access time, unlimited read/write endurance, low operating voltage and high storage density. The etching of MTJ stack with good properties is one of a key process for the realization of high density MRAM. In order to achieve high quality MTJ stack, the use of CoFeB and IrMn magnetic films as free layers was proposed. In this study, inductively coupled plasma reactive ion etching of CoFeB and IrMn thin films masked with Ti hard mask was investigated in a $Cl_2$/Ar gas mix. The etch rate of CoFeB and IrMn films were examined on varying $Cl_2$ gas concentration. As the $Cl_2$ gas increased, the etch rate monotonously decreased. The effective of etch parameters including coil rf power, dc-bais voltage, and gas pressure on the etch profile of CoFeB and IrMn thin film was explored, At high coil rf power, high dc-bais voltage, low gas pressure, the etching of CoFeB and IrMn displayed better etch profiles. Finally, the clean and vertical etch sidewall of CoFeB and IrMn free layers can be achieved by means of thin Ti hard mask in a $Cl_2$/Ar plasma at the optimized condition.

• Proceedings of the Korean Vacuum Society Conference
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• 2010.02a
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• pp.213-213
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• 2010

Magnetic random access memory (MRAM), based on magnetic tunnel junction (MTJ) and CMOS, is one of the best semiconductor memories because it can provide nonvolatility, fast access time, unlimited read/write endurance, low operating voltage and high storage density. For the realization of high density MRAM, the etching of MTJ stack with good properties is one of a key process. Recently, there has been great interest in the MTJ stack using MgO as barrier layer for its huge room temperature MR ratio. The use of MgO barrier layer will undoubtedly accelerate the development of MTJ stack for MRAM. In this study, high-density plasma reactive ion etching of MgO films was investigated in an inductively coupled plasma of $Cl_2$/Ar gas mixes. The etch rate, etch selectivity and etch profile of this magnetic film were examined on vary gas concentration. As the $Cl_2$ gas concentration increased, the etch rate of MgO monotonously decreased and etch slop was slanted. The effective of etch parameters including coil rf power, dc-bais voltage, and gas pressure on the etch profile of MgO thin film was explored, At high coil rf power, high dc-bais voltage, low gas pressure, the etching of MgO displayed better etch profiles. Finally, the clean and vertical etch sidewall of MgO films was achieved using $Cl_2$/Ar plasma at the optimized etch conditions.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2005.10a
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• pp.794-797
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• 2005

The automatic load transfer switch (ALTS), a kind of electric power switch, typically automatically transfers electrical loads from a normal electrical power source to an emergency electrical power source upon reduction or loss of normal power source voltage. It can also automatically re-transfer the load to the normal power source when the normal voltage has been restored within acceptable limits. The transfer operation of ALTS is accomplished by a spring-driven linkage mechanism. In order to control or delay the transfer switching time, the ALTS studied in this paper uses the superposed leaf springs, which are subjected to impact leadings in contacting with electrical contacts. Therefore, to confirm whether the springs has enough mechanical endurance in ALTS, we build a finite element model of the superposed lear springs using LS-DYNA and perform the impact and fatigue analysis.

• Preventive Nutrition and Food Science
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• v.4 no.3
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• pp.184-187
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• 1999

Increase in fat mobilization by capsaicin(CAP) was investigated in high-fat-fed mice using an adjustable current water pool. Male ICR 7-wk-old mice were fed a high fat diet [50% total energy content in the diet(E%) fat, 20 E% protein, 30E% carbohydrate] for 2 wk and one group (HCAP) was orally administered CAP at 2 h before swimming. After being accustomed to swimming , the mice were subjected to forced swimming every 2d in the current water pol and the total swimming period until exhaustion was measured . The total swimming period was used as index of swimming capacity. Swimming time to exhaustion of treated mice was significantly longer than that of the high-fat-fed control group (100.2$\pm$10.6 vs. 58.0$\pm$8.5min, P<0.01) after 2wk of training. The concentration of serum-free fatty scids gradually increased up to 2 h in CAP -administered mice. The perirenal adipose tissue weight of CAP -administered mice (HCAP) before swimming was lower than that of the high-fat-fed mice adminstered placebo solution (HP) which had not ingested CAP during the 2 wk. These results suggest that the increase of swimming capacity of CAP-administered high-fat-fed mice was due to an increase of fat mobilization that was induced by CAP.

• Women's Health Nursing
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• v.27 no.3
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• pp.209-219
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• 2021

Purpose: The purpose of this study was to describe pregnant women's lived experiences of hospitalization due to preterm labor in Korea. Methods: This qualitative study adopted a phenomenological approach. Individual in-depth interviews were conducted with nine participants, over the age of 20 years, who had been hospitalized for more than 1 week after being diagnosed with preterm labor. All interviews were audio-taped and verbatim transcripts were made for analysis. The data were analyzed following Colaizzi's phenomenological method. Results: The participants' ages ranged from 26 to 36 years, and all were married women. They were hospitalized for 13.1 days on average. Five thematic clusters emerged from the analysis. 'Withstanding hospitalization for the fetus's well-being' describes women's feelings during preterm labor and their endurance during their prolonged hospitalization, rooted in their conviction that the fetus comes first. 'Endless frustration in the hospital' encompasses women's emotions while lying in bed and quietly thinking to themselves. 'Unmet physiological needs' describes participants' awareness of their inability to independently handle human physiological needs given the need for careful and limited movement. 'Gratitude for the support around oneself' reflects the support from family and medical staff. 'Shifting perceptions and accepting one's circumstances' describes accepting hospitalization and making efforts to spend their remaining time in the hospital in a meaningful way. Conclusion: The findings in this study provide a deeper understanding and insights into the experiences of Korean women with preterm labor during hospitalization, underscoring the need to develop interventions for these patients.

• Child Health Nursing Research
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• v.27 no.3
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• pp.211-224
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• 2021

Purpose: Obesity among children from low-income families is becoming a social problem. The aim of this study was to evaluate the effectiveness of an obesity prevention program that included physical activity, nutrition education, behavioral modification, and primary caregiver participation components among children from low-income families. Methods: The study analyzed a nonequivalent control group using a pretest-posttest design. A total of 77 children were recruited from six community childcare centers using purposive sampling. For the intervention group (n=40), the pretest was administered before the combined intervention program involving the participants' primary caregivers was conducted for 8 weeks. The posttest was conducted immediately after the program and again four weeks after the program. Results: Flexibility (F=4.64, p=.020), muscular endurance (F=11.22, p<.001), nutritional knowledge scores (F=4.79, p=.010), body image satisfaction scores (F=4.74, p=.012), and self-esteem scores (F=3.81, p=.029) showed significant differences and interactions between group and time for the intervention and control groups. Conclusion: Strategies to actively engage the primary caregivers of low-income families in children's obesity programs are needed. Obesity prevention programs for children based on the program in this study should be routinely developed, and continuing attention should be given to children from low-income families.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.18 no.6
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• pp.9-18
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• 2019

This study derives load characteristics and analyzes the safety of plowshares operating in dry fields. We mounted a three-blade, reversible plow on a 23.7 kW tractor and measured the plow's tractive force as well as the torque from the engine output shaft on the rear axle under various working speeds (L4, M1, M2, M3). We chose a Korean test site of Seomyeon, Chuncheon with sandy soil texture, as determined using the USDA method. We constructed the load spectrum for torque and tractive force using measured data and derived the fatigue life of the plowshare from a stress-cycle (S-N) curve of the plow material. Our results show that the M3 gear maximizes the driving shaft torque loads and, applying the tractive force load spectrum, creates a cumulative damage sum of $4.14{\times}10^{-5}$. Considering sampling time, we estimate a fatigue life of 805 hours while using the M3 gear. When using the other working speeds, however, all of the stress levels fell within the endurance limits and, therefore, our model predicts infinite plowshare lifetimes. For this analysis, we used a yield strength of 1,079 MPa for the plowshare and static safety factors, analyzed using the maximum stress, between 6.83 and 8.63 under each working speed.