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Jeong‑Han Lee,Ik‑Hyun Oh,Jun‑Ho Jang,Ju‑Hun Kim,Sung‑Kil Hong,Hyun‑Kuk Park 대한금속·재료학회 2021 METALS AND MATERIALS International Vol.27 No.5
In this study, Al, Cr and Si fine powders were alloyed by planetary ball milling to investigate their microstructural evolution,following their mechanical alloying behavior. The formation of Al(Cr) supersaturated solid solution by the Cr grainsembedded in Al-matrix, which contributed substitutional structure is discussed in relation to their structural evolution inaccordance with the distortion of a crystal lattice. The compacts of Al–Cr–Si alloys were prepared by rapid sintering withina short time by dense consolidation above the density of 99.9% as the formation of intermetallics, except in the case of thedistribution of single-phases induced by the Al-melting. The formation behavior of intermetallics was dominated by dependenceon the structures of the milled-powder and subsequent sintering temperature. To estimate the consolidated behaviorsof compacts, various approaches derived from TEM and XRD analysis were taken to obtain microstructural evidences ofthe inter-diffusion, following the presence of thermally stable intermetallics.
Jeong‑Han Lee,Ik‑Hyun Oh,Ju‑Hun Kim,Sung‑Kil Hong,Hyun‑Kuk Park 대한금속·재료학회 2021 METALS AND MATERIALS International Vol.27 No.9
Densely consolidated WC-based hard materials with 5–20 vol% ZrSiO4was fabricated by spark plasma sintering at 1400 ℃ ata constant heating rate of 70 ℃/min−1. To achieve mechanical alloying of WC-ZrSiO4, planetary ball milling was carried outfor 12 h, during which the brittle-brittle components (WC-ZrSiO4) became fragmented and their particles became refined. Itwas observed that certain, specific, non-isothermal sintering kinetics, such as apparent activation energy, sintering exponents,and densification strain, affected the densification behavior. The evolution of phase structure from powder to compact wasfound to be related the lattice distortion and micro-strain in the basal planes of WC. By examining the mechanical propertiesof the samples, it was that the added zircon content leads to enhanced fracture toughness (12.9 MPa m1/2) owing to thepresence of WC-ZrSiO4 in the cemented carbide. In fact, the microcrack propagation of the fracture passed through zirconfrom a transgranular to a ductile component (fcc) where the crack tips could be absorbed.
Jeong‑Han Lee,Ik‑Hyun Oh,Jun‑Ho Jang,Ju‑Hun Kim,Sung‑Kil Hong,Hyun‑Kuk Park 대한금속·재료학회 2021 METALS AND MATERIALS International Vol.27 No.3
The aim of this study is to investigate the structural evolution and mechanical properties of TiAlSiN coatings when processedby the arc ion plating method. To form a hard coating, Ti, Al, and Si powders were mechanically alloyed by planetary ballmilling; the powders were then densely compacted during a rapid sintering process into a ternary system coating, i.e. TiAlSi. The evolution of the structural phase from a powder to a compact material is dominated considerably by phase states suchas a supersaturated solid solution or intermetallic compounds. In the case of coating layers, the factors that determine thestructural evolution are associated with the phase stability of the nano-crystalline structure that in turn is associated withthe Ti/Al composition ratio. Motivated by this, we performed experiments to investigate the distribution of microstructures;the material’s binding energy, quantitative properties, transformation of crystal structure, and distribution of amorphous/crystalline were all recorded. In particular, the relationship between the physical and chemical properties during the coatingprocess is considered to be the dominant factor controlling the orientation and morphology of that zone (1, T, and 2). TheTiAlSiN coating layer was found to have hardness above 45 GPa and an adhesion above 100 N. In other words, understandingthe evolution and structure of TiAlSin helped us to produce a material with excellent properties that can be used as a hardcoating. Specifically, these properties were induced by a grain refinement of the nano-crystalline structure that correspondsto an increase in the silicon nitride contents.
Park, Jinbong,Jeon, Yong-Deok,Kim, Hye-Lin,Lim, Hara,Jung, Yunu,Youn, Dong-Hyun,Jeong, Mi-Young,Kim, Hyun-Ju,Kim, Sung-Hoon,Kim, Su-Jin,Hong, Seung-Heon,Um, Jae-Young Hindawi Publishing Corporation 2013 Evidence-based Complementary and Alternative Medic Vol.2013 No.-
<P>Obesity has become a major health threat in developed countries. However, current medications for obesity are limited because of their adverse effects. Interest in natural products for the treatment of obesity is thus rapidly growing. Korean Medicine (KM) is characterized by the wide use of herbal formulas. However, the combination rule of herbal formulas in KM lacks experimental evidence. According to <I>Shennong's Classic of Materia Medica</I>, the earliest book of herbal medicine, <I>Veratrum nigrum</I> (VN) has antagonistic features against <I>Panax ginseng</I> (PG), and the PG-VN pair is strictly forbidden. In this study, we have shown the effects of PG, VN, and their combination on obesity in high-fat (HF) diet-induced obese mice and in 3T3-L1 cells. PG, VN, and PG-VN combination significantly reduced weight gain and the fat pad weight in HF diet-induced obese mice. They also significantly decreased lipid accumulation and the expressions of two major adipogenesis factors, PPAR<I><I>γ</I></I> and C/EBP<I><I>α</I></I>, in 3T3-L1 cells. In addition, the PG-VN combination had synergistic effects compared with the mixture of extracts of PG and VN on inhibition of PPAR<I><I>γ</I></I> and C/EBP<I><I>α</I></I> expressions at lower doses. These results indicate a new potential anti-obese pharmacotherapy and also provide scientific evidence supporting the usage of herbal combinations instead of mixtures in KM.</P>
Seasonal and diel abundance and feeding patterns of Chaoborus flavicans in Sang-Chun reservoir
Jeong, Ga-Ram,Park, Sang-Kyu The Korean Society for Integrative Biology 2010 Animal cells and systems Vol.14 No.4
To document the basic ecological aspects of Chaoborus species, which has never been reported in Korea, we attempted to identify the species, to monitor seasonal and vertical dynamics, and to elucidate trophic relations of the species in Sang-Chun reservoir. Using morphological characteristics, we identified the collected samples as C. flavicans. Also, we compared the distribution of C. flavicans, Daphnia rosea and chlorophyll a to observed seasonal dynamics. The increase of C. flavicans was observed 1-2 weeks after the increase of D. rosea. Survey of diel vertica migration patterns in the summer season showed that C. flavicans were in hypolimnion at daytime, but moved to the epilimnion at night. Finally, to determine trophic relationships in Sang-Chun reservoir, additional studies on the food web were undertaken by stable isotope analysis. Chaoborus flavicans I-II instars appear to be filter feeders based on carbon isotope values. Trophic levels of C. flavicans III-IV instars were shown to be higher than other zooplankto based on nitrogen isotope values.
Clothing Pressure of selected Support Panty Stockings
(Jeong Eun Park),(Su Kwang Sung),(Min Kyu Song) 한국의류산업학회 2000 한국의류산업학회지 Vol.2 No.5
The purpose of the study was to obtain the basic data on the self-adjusting ability of the support panty stockings. Ten healthy women in the twenties were selected as subjects and clothing pressure of 9 support panty stockings made of single covered yarn (SCY) and double covered yarn (DCY) were measured under the standard environmental condition for the study. Data was analysed statistically according to body postures, sides, and parks. The results were as follows: Clothing pressure according to body posture was order of `sitting-on-a-chair`, `stepping-up-a-stair`, and `standing`. High clothing pressure was obtained in the parts of calf (9.4 gf/㎠) in `standing` and knee (9.7 and 16.5 gf/㎠) in both `stepping-up-a-stair` and `sitting-on-a-chair`, respectively. The order of clothing pressure with body sides was `front`, `side`, and `back`. The highest clothing pressure was knee (18.8 gf/㎠) on the front, thigh (8.8 gf/㎠) on the side, and calf (6.4 gf/㎠) on the back. Clothing pressure of DCY at abdomen and knee was a little higher than those of SCY 3. In terms of material structure variation, clothing pressure of thigh, calf and ankle with SCY was a little higher than those with DCY, while clothing pressure of abdomen and knee with DCY was a little higher than those with SCY.
김정열(Jeong-Yeol Kim),정동열(Dong-Yeol Chung),박승상(Shung Sang Park),백종현(Jong-Hyeon Peck) 대한설비공학회 2009 대한설비공학회 학술발표대회논문집 Vol.2009 No.-
The purposes of this work were suggested and validated the methods of heat recovery from dyeing wastewater exhausted in Sihwa and Banwol dyeing industrial park. We analyzed the present conditions of heat supplies and demands. So it was made a selection of the system combined heat exchanger for waste heat recovery and the high temperature heat pump. We decided the specifications of the heat recovery facilities. After this, economical assessment is performed to this system. The payback periods are within 4 years, 20 years and 5 years in case of K company, S company and A company. In addition, when they are produced the heat of same capacity, quantities of pollutants from used fuels were calculated.
소비자 조사와 착의 실험을 통한 온도감응형 기능성 의류개발을 위한 기초연구
상정선 ( Jeong-seon Sang ),정경화 ( Kyunghwa Chung ),박주현 ( Juhyun Park ),오경화 ( Kyung Wha Oh ) 한국의류산업학회 2017 한국의류산업학회지 Vol.19 No.1
In this research, consumer awareness investigation and wearing test were carried out for obtaining useful data on the development of thermo-sensitive functional clothing material. A survey involved 216 people in Seoul and Kyeonggi- do, and 200 questionnaires data were analyzed by descriptive statistics and frequency using SPSS 17.0. Four healthy men in twenties were participated for wearing test. Subjects in normal loungewear were exposed to temperature change from the initial temperature 30oC down to 5oC for an hour in a climate chamber. The environmental temperature, surface temperature of garment and skin were measured. As a result, most of respondents have all season clothing products such as underwear, hosiery, and jogging suit for loungewear. Also, thermo regulator y functional clothes are frequently used as underwear and sweat shirt. The consumer awareness investigation on thermo regulatory functional clothing showed that the most important key buying factor is quick climate temperature response, easy maintenance, design and cost, in that order. Surface temperature of garment went down with the cooling down of environmental temperature. The lower environmental temperature, the greater temperature difference by body part showed. Skin temperature change by environmental temperature showed similar tendency of garment surface temperature. In comparison between garment surface and body skin, temperature difference became larger under the lower environmental temperature.
김동현 ( Dong Hyeon Kim ),김의경 ( Eui Gyeong Kim ),박상병 ( Sang Byeong Park ),이정환 ( Jeong Hwan Lee ) 한국산림과학회 2010 한국산림과학회지 Vol.99 No.4
This study carried out the recognition of appropriate forest managements and directions in Jirisan National Park. For this purpose, we undertook interview survey about the recognition of forest management in Jirisan National Park from ecological and forest research fields` experts. From the statistical analysis results, it was founded that the difference among respondents` types was detected about recognition of forest management in National park. However, all the respondent types recognized that the forest management in National park is essential. So the forest management in national park by forest experts and relevant institutions are revealed needed.