• Transactions of Materials Processing
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• v.26 no.5
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• pp.271-276
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• 2017

A tee is the most common pipefitting used to combine or divide fluid flow. Tees can connect pipes of different diameters or change the direction of a pipe run. To manufacture tee type of stainless steel pipe, combinations of punch piercing and burr forming have been widely used in the industry. However, such method is considerably time consuming with regard to performing empirical work necessary to attain process conditions to prevent upper end tearing of the tee product and meet target tee height. Numerous experiments have shown that the piercing profile is the main cause of defects mentioned above. Furthermore, the mold design is formed through trial and error according to pipe diameters and changes in requirements. Thus, the objective of this study was to perform piercing and burring process analysis via finite element analysis using DYNAFORM to resolve problems mentioned above. An optimization design method was used to determine the piercing punch profile. Three radii of the piercing punch (i.e., large, small, and joined radii) were selected as design variables to minimize thinning of a tee pipe. Based on results of correlation and multiple regression analyses, we developed a predictive approximation model to satisfy requirements for both thickness reduction and target height. The new piercing punch profile was then applied to actual tee forming using the developed prediction equation. Model results were found to be in good agreement with experimental results.

• Human Ecology Research
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• v.60 no.1
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• pp.53-68
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• 2022

Using a person-centered approach, the current study investigated latent profiles for the emotional and behavioral problems of students in sixth-grade in elementary school and second grade of middle school. The aim was to explore latent transition patterns and verify the factors affecting the transitions. The participants were 1,937 adolescents who responded to the 3^rd year (6^th grade of elementary school; Time 1), 4^th year (1^st grade of middle school), and 5^th year (2^nd grade of middle school; Time 2) of the Korean Children Youth Panel Study. Latent profile and latent transition analyses were performed. The results were as follows: first, the latent profile of emotional and behavioral problems changed from Time 1 to Time 2. The latent groups at Time 1 were classified into low, moderate, high, and externalizing-dominant, whereas at Time 2, five groups were identified: low, moderate, high, externalizing-dominant, and withdrawal-dominant. Second, transition analyses revealed that although 22.3-57.0% of latent groups remained unchanged, there were significant changes over time between groups, as a new group ('withdrawal-dominant') emerged in Time 2. Third, different factors influenced the latent profile transition of emotional and behavioral problems depending on the transition pattern. Higher levels of self-esteem, better relationships with peers and teachers, and lower levels of parental inconsistency meant emotional and behavioral problems had not worsened at Time 2. The results suggest that early interventions are needed during the transition from childhood to early adolescence.

• Journal of the Society of Naval Architects of Korea
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• v.60 no.3
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• pp.202-211
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• 2023

The profile shops in shipyards produce section steels required for block production of ships. Due to the limitations of shipyard's production capacity, a considerable amount of work is already outsourced. In addition, the need to improve the productivity of the profile shops is growing because the production volume is expected to increase due to the recent boom in the shipbuilding industry. In this study, a scheduling optimization was conducted for a parallel welding line of the profile process, with the aim of minimizing tardiness and the number of set-up changes as objective functions to achieve productivity improvements. In particular, this study applied a dynamic scheduling method to determine the job sequence considering variability of processing time. A Markov decision process model was proposed for the job sequence problem, considering the trade-off relationship between two objective functions. Deep reinforcement learning was also used to learn the optimal scheduling policy. The developed algorithm was evaluated by comparing its performance with priority rules (SSPT, ATCS, MDD, COVERT rule) in test scenarios constructed by the sampling data. As a result, the proposed scheduling algorithms outperformed than the priority rules in terms of set-up ratio, tardiness, and makespan.

• Korean Journal of Materials Research
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• v.33 no.2
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• pp.54-62
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• 2023

The most comprehensive and particularly reliable method for non-destructively measuring the residual stress of the surface layer of metals is the sin²ψ method. When X-rays were used the relationship of ε_φψ-sin²ψ measured on the surface layer of the processing metal did not show linearity when the sin²ψ method was used. In this case, since the effective penetration depth changes according to the changing direction of the incident X-ray, σ_φ becomes a sin²ψ function. Since σ_φ cannot be used as a constant, the relationship in ε_φψ-sin²ψ cannot be linear. Therefore, in this paper, the orthogonal function method according to Warren's diffraction theory and the basic profile of normal distribution were synthesized, and the X-ray diffraction profile was calculated and reviewed when there was a linear strain (stress) gradient on the surface. When there is a strain gradient, the X-ray diffraction profile becomes asymmetric, and as a result, the peak position, the position of half-maximum, and the centroid position show different values. The difference between the peak position and the centroid position appeared more clearly as the strain (stress) gradient became larger, and the basic profile width was smaller. The weighted average strain enables stress analysis when there is a strain (stress) gradient, based on the strain value corresponding to the centroid position of the diffracted X-rays. At the 1/5 I_max max height of X-ray diffraction, the position where the diffracted X-ray is divided into two by drawing a straight line parallel to the background, corresponds approximately to the centroid position.

• Asian Journal of Turfgrass Science
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• v.23 no.2
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• pp.219-228
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• 2009

The construction procedures and artificial turf maintenance program on golf course definitely influence on the distortion of its environment. Soil microbial communities in soil profile were affected directly by those practises on turf areas. In Jeju island, the environmental impact assessment has been required to apply the first quality class granular activated carbon(GAC), which has a high absorbent character to agricultural chemicals, on the soil profiles of golf green system to reduce the pesticide leaching to ground water. This research was carried out to analyze the changes of microbial communities and chemical properties on soil profiles where GAC had been applied at the construction stage at two golf courses in Jeju. The changes of soil microbial population and chemical properties associated with construction methods of soil profile and agrochemical management program were analyzed by monthly at the surface and sub-soil profiles during April through October, 2007. The total numbers of bacteria and fungi, soil moisture content, soil physio-chemical properties were measured on greens and fairways of the both golf courses with different GAC treatment on the green and fairway soil profiles. The results showed that GAC had positive effects on the water holding capacity, pH and EC, however, it did not improved the holding capacity of available nutrients ${NO_3}^-,{NH_4}^+$, and phosphorus by its sorption phenomenon. In microbial count test, the total numbers of bacteria and fungi showed a great variation during sampling dates. That may directly relate to the agrochemical application, however, the ratio of total bacterial number versus total fungus number showed a constant value on a sub-soil of 15~30cm depth. Thus, the construction method of GAC in soil profile, and application of fertilizer and pesticide, both impacted on the changes of microbial population. It's means that the construction method of soil profile and turf management using agro-materials might greatly affect on the turfgrass culture and the environment of golf course.

• Korean Journal of Agricultural and Forest Meteorology
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• v.17 no.3
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• pp.227-235
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• 2015

Using eddy covariance method, net ecosystem exchange (NEE) of $CO_2$ ($F_{CO_2}$), $H_2O$ (LE), and sensible heat (H) can be approximated as the sum of eddy flux ($F_c$) and storage flux term ($F_s$). Depending on strength and distribution of sink/source of scalars and magnitude of vertical turbulence mixing, the rates of changes in scalars are different with height. In order to calculate $F_s$ accurately, the differences should be considered using scalar profile measurement. However, most of flux sites for agricultural lands in Asia do not operate profile system and estimate $F_s$ using single-level scalars from eddy covariance system under the assumption that the rates of changes in scalars are constant regardless of the height. In this study, we measured $F_c$ and $F_s$ of $CO_2$, $H_2O$, and air temperature ($T_a$) using eddy covariance and profile system (i.e., the multi-level measurement system in scalars from eddy covariance measurement height to the land surface) at the Chengmicheon farmland site in Korea (CFK) in order to quantify the differences between $F_s$ calculated by single-level measurements ($F_s_{-single}$ i.e., $F_s$ from scalars measured by profile system only at eddy covariance system measurement height) and $F_s$ calculated by profile measurements and verify the errors of NEE caused by $F_s_{-single}$. The rate of change in $CO_2$, $H_2O$, and Ta were varied with height depending on the magnitudes and distribution of sink and source and the stability in the atmospheric boundary layer. Thus, $F_s_{-single}$ underestimated or overestimated $F_s$ (especially 21% underestimation in $F_s$ of $CO_2$ around sunrise and sunset (0430-0800 h and 1630-2000 h)). For $F_{CO_2}$, the errors in $F_s_{-single}$ generated 3% and 2% underestimation of $F_{CO_2}$ during nighttime (2030-0400 h) and around sunrise and sunset, respectively. In the process of nighttime correction and partitioning of $F_{CO_2}$, these differences would cause an underestimation in carbon balance at the rice paddy. In contrast, there were little differences at the errors in LE and H caused by the error in $F_s_{-single}$, irrespective of time.

• Proceedings of the Korea Water Resources Association Conference
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• 2006.05a
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• pp.1611-1615
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• 2006

The purpose of this study is to simulate the riverbed profile changes downstream of Daecheong re-regulation dam from 1988 to 2001, to evaluate the model's applicability and to predict a long-term riverbed-level variation between 2002 and 2017. As a result of simulation 14 sediment transport equations provided by GSTAR-1D, it was found that Acker's & White formula was the most stable relatively. The interval used to calculate its stability was 7 days for bankful discharge$(1,000m^2/s)$, 3 days for daily maximum flow$(4,273m^2/s)$, 1 day for hourly maximum flow$(7,605m^2/s)$ and minimum flow$(8.5m^2/s)$. The simulation results of river bed changes were evaluated and compared to its measure data from 1988 to 2001. It was showed that there was the degradation for a section between Daecheong re-regulation dam and Maepo water stage gage station due to bed-material, and the degradation for a reach between Maepo and Gongju water stage gage station due to massive aggregate collection. Also, as a result of simulating the river profile change for 2002 to 2017, it was predicted that the section between Daecheong re-regulation dam and Geumnam Bridge would remain as the present profile and the reach between Maepo and Gongju water stage gage station would have some degradations in several parts, which would be stable as a whole unless it was due to artificial river profile change.

• The Korean Journal of Food And Nutrition
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• v.29 no.5
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• pp.785-794
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• 2016

This research was conducted to evaluate quality changes in traditional Doenjang and manufactured Doenjang during a storage period of 8 weeks. Low-salt Doenjang and commercial Doenjang were purchased from different manufacturers and proximate analysis as well as changes in isoflavone, polyphenol, flavonoid contents of the samples were investigated using a mass spectrophotometer. The salinity of traditional Doenjang, low salt Doenjang, and commercial Doenjang were $13.2{\pm}1.15$, $7.17{\pm}2.74$, $10.67{\pm}0.35%$, respectively and the salt concentrations of the soybean pastes did not change during storage. After 8 weeks at $35^{\circ}C$, chromatic values of all the paste samples decreased somewhat, with traditional Doenjang exhibiting fewer changes as compared to manufactured Doenjang. Amino acid nitrogen, acidity, microbial population all tended to increase with time, although some samples showed fluctuations during the test period. Moreover, the total isoflavone contents of traditional Doenjang increased with storage time while that of manufactured Doenjang tended to decrease. The isoflavone aglycone was shown to be the highest in traditional Doenjang, while isoflavone glycoside was abundant in manufactured Doenjang. Total flavonoid contents showed similar trends regardless of samples; initial contents of total flavonoid was 0.6 mg/g which increased to more than twice to 1.4 mg/g at the end of storage period. Composition profile of Doenjang extracts was analyzed using UPLC-Q-ToF.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.22 no.6
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• pp.550-557
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• 2021

This study examined the latent groups regarding the changes and difficulties after becoming a single parent and analyzed the differences in the backgrounds and depressive levels according to each group. The data of 2,500 single parents from the 2018 Single Parent Family Survey were analyzed by Latent Profile Analysis (LPA). LPA indicated four-profile groups: 1) parenting stability group, 2) normal group, 3) economic stability group, and 4) potential-risk group. Its determinants included gender and economic status, including government funding type and employment status rather than academic status. Specifically, female single parents with an unemployed or low-income support household were more likely to be linked to the potential-risk group. In addition, the potential-risk group showed a higher depressive level than the parenting stability group, normal group, and economic stability group. The significance of this study is that distinguished intervention based on the characteristics of each group can promote the effectiveness of single-parent family support policy.

• Korean Journal of Poultry Science
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• v.21 no.3
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• pp.169-174
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• 1994

An experiment was conducted to establish a large scale production method of anti-serum against chicken IgA and to profile the developmental changes of serum IgA levels during the feeding period(from hatching to 7 weeks of age) in broiler chicks. Blood samples were taken from Hubbard chicken at the age of hatching, 3 days of age, and weekly thereafter till to 7 weeks of age. The pure IgA was isolated from ammonium sulfate treated chicken bile juice by gel filtration chromatography ( Sepharose GL-6B) - The quantitative assay of serum IgA were carried by RID method. Developmental changes of serum IgA concentrations were 0.42 mg /mL at hatching, thereafter dicreased gradually, lowest at 1 week of age(0.17 mg /mL), and gradually increased to 7 weeks of age(2.73 mg /mL). There was no sexual difference in serum IgA level, but female chicks showed higher IgA levels than male chicks during the experimental period.