Influence of heat‑treated Al-Si coating on the weldability and microstructural inhomogeneity for hot stamped steel resistance nut projection welds

Eun‑Joon Chun,Sung‑Sang Lim,Young‑Tae Kim,Ki‑Sung Nam,김영민,Young‑Whan Park,Siva Prasad Murugan,Yeong‑Do Park 대한금속·재료학회 2019 METALS AND MATERIALS International Vol.25 No.1

Resistance nut projection weldability of Al–Si coated hot stamped steel (HSS) was investigated under the viewpoint of weldablecurrent range and joint strength (pull-out load). The microstructural inhomogeneities in the welds were also studied inorder to elucidate the factors affecting the joint strength of the welds. The weldability of the given Al–Si coated HSS wascompared with the weldability of an identical HSS without the Al–Si coating (Al–Si coating was polished out) and Zn coateddual phase steel. The weldable current range of Al–Si coated HSS was found to be narrower than that of the other materials. Furthermore, the average pull-out load within the weldable current range of the Al–Si coated HSS was the lowest among thethree materials. The reason for poor weld mechanical property of the Al–Si coated hot-stamped steel was attributed to themicrostructural inhomogeneities such as unmixed Al–Si coating layer at the edge of the nugget and the second phase Fe3(Al,Si) intermetallic compound. The formation of Fe3(Al, Si) phase was attributed to the solidification segregation of Al and Siduring the weld solidification and was confirmed with the numerical analysis of solidification segregation.

축구선수의 Detraining과 Retraining이 혈청지질 및 호르몬농도에 미치는 영향

정정화,박재현,채종훈,성혜련,황지인,윤미숙,노금선,윤종관,윤영학,노순덕,정경숙,박일규,김은희,박현태,박상갑 대한스포츠의학회 1999 대한스포츠의학회지 Vol.17 No.1

The purpose of this study was to investigate the effects of detraining and retraining on serum lipid and hormones in soccer players. Subjects were seven male high-school soccer players. V˙O_2max was determined for each subjects by administering a treadmill test(initial speed: 90m/min, grade: 5%, increasing speed per 3 min: 30m/min). Serum lipid(T-C, TG, HDL-C LDL-C) and hormones(epinephrine, norepinephrine, growth hormones, cortisol) were assayed pre and post detraining in 10, 20, 30 days after retraining. The repeated ANOVA was used to determine significant differences. The 0.05 level of significance was as critical level for the study. The results of the study were as follows: 1. V˙O_2max(ml/min) were 3576.3±204.2ml/min pre detraining, 3234.1±198.9 ml/min post detraining. There are significant(p<.05) difference between pre and post detraining. In 10, 20, 30 days after retraining, V˙O_2max(ml/min) were 3601.4±170.9 ml/min. There were significantly(p<.05) increased in retraining periods. 2. V˙O_2max(ml/kg/min) were significantly(p<.05) decreased from 62.3±2.9 ml/kg/min to 55.9±4.7 ml/kg/min in detraining. In 10, 20, 30 days after retraining, V˙O_2max(ml/kg/min) were 62.4±3.4ml/kg/min, 62.7±2.3ml.kg/min, 67.3±7.2ml/kg/min respectively. There were significantly(p<.05) increased in retraining periods. 3. T-C were significantly (p<.05) increased from 166.6±8.5mg/dl to 175.3±10.3 mg/dl in detraining. In 10, 20, 30 days after retraining, T-C were 160.1± 3.2mg/dl, 156.7±3.7mg/dl, 140.3±9.0mg/dl. There were significantly(p<.05) decreased in retraining periods. 4. HDL-C were 61.4±6.6mg/di pre detraining, 5.3±6.6mg/dl post detraining. There are significant(p<.05) difference between pre and post detraining. In 10, 20, 30 days after retraining, HDL-C were 56.9±7.1mg/dl, 56.4±9.2mg/dl, 57.7±9.1mg/dl respectively. There were no significant difference in retraining periods. 5. The hormones(epinephrine. norepinephrine, growth hormone, cortisol) were changed as same patterns. Epinephrine were 26.0±7.0[g/ml pre detraining, 24.6±3.2pg/ml post detraining. In 10, 20, 30 days after retraining, epinephrine were 26.9±5.6pg/ml, 30.6±6.2pg/ml, 29.4±5.6pg/ml respectively. There were no significant difference in retraining periods. In conclusion, HDL-C, epinephrine, norepinephrine, growth hormone and cortisol were decreased, T-C, LDL-C and TG were increased in detraining. But HDL-C, epinephrine, norepinephrine, growth hormone and cortisol were increased, T-C, LDL-C and TG were decreased in retraining.

예비 유아 교사의 자아상태 유형에 관한 연구

박화윤,최인숙,천은영 한국영유아보육학회 2003 한국영유아보육학 Vol.0 No.34

The purpose of this study is to analyze the preservice teacher' ego state type and to provide basic data for personality education and teacher training. The subjects of this study were 234 students majoring in early childhood in 2 universities and 112 students majoring in early childhood in 2 colleges of Jeonbuk province. The instrument of this study were 「Ego gram Check list」that were developed by Dusay(1977). The results of this study were as follows : 1. As compared among the grade, all groups were showed that NP type was predominant position, and both A type and FC type were showed to be a significant difference. 2. As compared between university students and college students, two Groups were also showed that NP type was predominant position, and both A type and FC type were showed to be a significant difference.

사용자 인식 스마트 홈 미러

최건영,고성화,김종옥,박은서,김완규,백경동,박동규 순천향대학교 부설 산업기술연구소 2021 순천향 산업기술연구소논문집 Vol.27 No.2

The Internet of Things, the core of the Fourth Industrial Revolution, is growing by incorporating various technologies into various fields. Among them, smart home systems that apply IoT technology to home environments are being actively studied. The home hub market, a means of communication for smart homes, is also developing at the same time. As the home hub market develops, security threats are also increasing accordingly. In this paper, 'Smart Home Mirror' is implemented by combining mirror and IoT technologies so that users can use them to communicate with smart home applications and other devices. To meet security issues, users in it are recognized by using face recognition technology and AES between all data communications in it is applied. The proposed device’s usefulness is approved by implementing it in smart home environments.

아크릴아미드 고정 구멍갈파래에 의한 중금속 Cd(Ⅱ), Pb(Ⅱ) 이온의 흡착특성 (Ⅰ)-Column법

박광하,권영두,정영진,장은경 한국공업화학회 2004 공업화학 Vol.15 No.1

본 연구에서는 동해안 해조류인 구멍갈파래를 아크릴아미드에 고정하여, Cd(Ⅱ) 및 Pb(Ⅱ) 중금속 이온의 흡착 특성을 살펴보았다. 수순한 Ulva pertusa 및 Si-Ulva pertusa 흡착제보다는 아크릴아미드에 고정화된 Ulva pertusa의 경우 많은 양의 중금속이 흡착되었으며, Pb(Ⅱ) 이온이 Cu(Ⅱ) 이온보다 더 잘 흡착되는 것으로 나타났다. 흡착제의 농도가 작은 경우 중금속 이온의 흡착량은 pH에 큰 영향이 없었으나, 흡착제의 농도가 클 경우 중금속 이온의 흡착량은 pH에 큰 영향을 받았다. pH에 따른 중금속 이온의 흡착량은 pH 10.5 > 8.5 > 7.0 > 5.5 > 3.5 순으로 나타났다. 아크릴아미드에 고정화된 Ulva pertusa의 단위 질량에 대해 Cd(Ⅱ) 및 Pb(Ⅱ) 이온의 최대 흡착량은 각각 최대 8.73 ㎎과 13.20 ㎎으로 나타났다. 또한 Cd(Ⅱ) 및 Pb(Ⅱ) 이온의 회수율은 pH에 따라 다소 차이가 있었으나, 각각 61.3~75.5% 및 61.4~54.1%로 나타났다. 중금속 이온의 회수에 있어서 산성 조건이 알칼리성 조건보다 효율적이었으며, 본 실험에 의한 중금속 이온의 흡착 특성은 Freundlich 흡착 특성과 잘 일치하는 것으로 나타났다. Adsoprtion characteristics of Cd(II) and Pb(II: heavy metal ions onto the Acrylamide-immobilized Ulva pertusa, and algae of the eastern coastal area. was examined in this work. Much amounts of heavy metal ions were adsorbed onto the Acrylamide-immobilized than either bare Ulva pertusa or Si-Ulva pertusa. It was also observed that Pb(II) was more readily adsorbed on the algae that Cu(II). The adsorption amounts of heavy metal ions showed no great dependence on the pH value at low adsorbent concentration, but those were high dependent on pH value at high adsorbent concentration. The adsorption amounts of heavy metal ions were in the following order; pH 10.5 > 8.5 > 7.0 > 5.5 > 3.5. The maximum adsorption amounts of Cd(II) and PB(II) onto Ig of Acrylamide-immobilized Ulva pertusa were 8.73 mg and 13.20 mg, respectively. It was found that recovery yields of Cd(II) and Pb(II) ions were in the range of 61.3∼75.5% and 61.4∼54.1% depending on the pH level. In the heavy metal recovery, acidic condition was more efficient that alkaline condition. The adsorption behavior of these heavy metal ions was well matched with the Freundlich adsorption isotherm.

유아의 성격유형에 따른 놀이성에 관한 연구

박화윤,천은영 한국영유아보육학회 2004 한국영유아보육학 Vol.0 No.37

The purpose of this study is to examine personality types of young children and to determine if there is any relationship of the personality with the playfulness of young children's. For this purpose, personality tests were conducted to 5-year old Kindergarten children according to the Korean version of MMTIC. Their playfulness was also measured by Barnett's playfulness measuring instrument(1991). As a result, most children turned out to have intuitive, feeling and perceiving personalities as personality indicators. U-Band indicators were also revealed as a type of indecisive personality. In the difference of playfulness according to children's personality the preferred indicator of thinking-feeling type was found to be associated with psychological functional type of personality. A significant relationship was shown between the perceptive spontaneity and expression of joyfulness. These findings indicated that INFP and ENFP are dominant types of personality in 5-year old children, but the personality tended to be indecisive may continue to change and, thus, their playfulness shall be understood on the basis of functional types of personality.

티타늄 상에 강유전성 barium titanate 박막 형성과 분극처리에 의한 유사체액 내에서의 calcium phosphate 생성 증진

박영준,이용렬,황규석,김은주,임용무,이기헌 대한치과기재학회 2001 대한치과재료학회지 Vol.28 No.2

This study was performed to fabricate a ferroelectric barium titanate (BaTiO₃, BTO) thin film on Ti substrate and to evaluate the effect of poling treatment for the improvement of calcium phosphate (Ca-P) formation. BTO thin-film was spin-coated on Ti substrate by dipping-pyrolysis technique using coating sol obtained by mixing Ba-naphthenate and Ti-naphthenate as starting substances. Pre-heating temperature of the BTO thin film was performed at 500℃ because organic-solvent was completely volatilized without any crystal growth, and the final heat treatment was performed at 600, 650, 700, 750, 800, 850℃, respectively. By repeating the coating and pre-heating procedure gor 20 times, homogeneous thin film of 0.7㎛ thickness could be fabricated, and it performed well during the poling treatment without breakdown. The final heating treatment of the BTO thin film at 750℃ produced a homogeneous crystalline structure without heterogeneous TiO₂formation, which was confirmed by field emission scanning electron microscope (FE-SEM) and X-ray diffraction analyser (XRD). An average grain size of 20∼30 ㎚ were confirmed by SEM observation. The final heat-treated BTO thin-films were polarized (Ep = 5 V/㎛) from 160℃ to 25℃ in heating chamber for 2 h. The negatively poled BTO thin film (N-BTO), non-poled BTO thin film (BTO), Ti substrate (Ti), and 600℃ heat-treated Ti (Ti-O) were immersed in SBF and Eagle's MEM solution for 15 days at 37℃. After the immersion period, the morphological and compositional changes of the surfaces were investigated using a FE-SEM and an energy dispersive X-ray spectrometer (EDX). After immersion in simulated body fluid (SBF), sodium chloride (Nacl) crystals were formed on Ti, Ti-O, and BTO surfaces due to anion adsorption (Cl), while Ca-P crystals were formed on N-BTO surfaces. We assumed that rapidly adsorded cations (Ca²□ ions) on the negatively charged surface at the initial stage acted as nuclei for the formation of Ca-P crystals. In MEM, sodium chloride (NaCl) was formed on Ti, and Ca-P layer including NaCl was formed on Ti-O. Weak and sparse Ca-P layers were formed on BTO, while thick, homogeneous, and dense Ca-P layer was formed on N-BTO, which was confirmed by FE-SEM and EDX. These results demonstrated that introducing a N-BTO on Ti is an effective method for the improvement of Ca-P formation in SBF and MEM. In conclusion, negatively charged ferroelectric BTO thin-film on Ti would improve the possibility of implant osseointegration.

강유전성 BaTiO₃의 분극처리에 의한 유사체액 내에서 Calcium Phosphate 생성

송종은,김은주,황규석,임용무,박영준 대한치과기재학회 2000 대한치과재료학회지 Vol.27 No.4

Barium titanate (BaTiO3; BTO) has wide application in industry, particularly in the manufacturing of dynamic random access memory chips, electro-optical switches, optical modulators, shutters, optical mixers, and sensors, owing to its ferroelectric and piezoelectric properties after poling treatment. There has recently been considerable interest in the properties of its role in osseointegration. In this study, we investigated the possibility of treating BTO by poling to improve osseointegration by examining the calcium phosphate (Ca-P) crystal growth behavior on the poled and non-poled BTO surfaces in simulated body fluids (SBF). The BTO samples were sintered at 1350℃ for 2 h in air, producing an average grain size of 7 ㎛, which were confirmed by SEM observation. The sintered BTO samples were then polarized (Ep=5 kV/cm) from 160℃ to 25℃ in a Si oil bath for 2 h. The poled and non-poled BTO samples were immersed in 1.5 SBF for 15 days, or 30 days at 37℃. After the immersion period, the morphological and compositional changes of the surface of the immersed BTO specimens were investigated using a field emission scanning electron microscope (FE-SEM) and an energy dispersive X-ray spectrometer (EDX). Qualitative analysis was then performed using fourier transform infrared (FTIR) analysis. Weak and coarse Ca-P crystals had grown on the surface of the non poled BTO, while a marked difference in the Ca-P forming pattern was visible for the poled BTO, showing the negatively charged surface induces a Ca-P layer more easily. We assumed that rapidly adsorbed cations (Ca2+ ions) on the negatively charged surface at the initial stage acted as nuclei for the formation of Ca-P crystals, while no nuclei would be available on the positively charged surface, due to the fact that sodium chloride (NaCl) crystals were formed owing to anion adsorption (Cl ions). In summary, these results demonstrate that poling the ferroelectric BTO surface negatively the possibility of implant osseointegration.

피부 병변을 동반한 악성조직구증 1예

조은택,박용관,김진호,강정원,천영욱,전익섭,박유환,전춘해 조선대학교 1995 The Medical Journal of Chosun University Vol.20 No.1

Malignant histiocytosis, originally described in 1939 as histiocytic medullary reticulosis by Scott and Robb-Smith, is a rare histiocytic proliferative disorder that often shows an acute onset and used to progress to death within a few months. This disorder characterized clinically by fever, generalized weakness, lymphadenopathy and hepatosplenomegaly, and shows a variable range of pancytopenia. Extranodal involvement is common, with an incidence ranging from 50% to as high as 90%, skin involves8ment was noted in 10% to 15%. Typical skin lesions were mainly founded in extremity. i.e. erythematous papule and nodule occasionally become to necrosis and ulceration. We experienced one case of malignant histiocytosis in a 46-years-old female. The major clinical findings are fever, malaise, hepatosplenomegaly and erythematous skin lesion. In the laboratory study, pancytopenia is noted on the peripheral blood. And also aggregation of many atypical histiocytes were shown on skin and bone marrow biopsy. So we reported one related case with malignant histiocytosis as well as reviewing literature .

유구치 상아질의 각 부위에 적용된 수종의 복합레진 접착제의 미세인장접착강도에 관한 연구

유정은,최영철,최성철,박재홍 大韓小兒齒科學會 2009 大韓小兒齒科學會誌 Vol.36 No.3

본 연구는 유구치 상아질의 각기 다른 부위(표층부, 심층부, 치경부)에서 복합레진 접착제의 접착강도를 비교, 평가하기 위하여 임상에서 흔히 사용하고 있는 서로 다른 4종의 접착방식(3-step total etch: 1군, 2-step total etch: 2군, 2 step self-etch: 3군, all-in-one: 4군)을 적용하고 복합 레진(Light-Core™ Core Build-Up Composite)을 적층한 후, 미세인장접착강도를 비교하였을 때 다음과 같은 결과를 얻었다. 1. 접착방식간의 비교에서 레진의 접착방식에 따른 상아질 각 부위에서의 미세인장접착강도는 제 1군이 표층부에서 뚜렷이 높았으나(p<0.05) 2, 3, 4군은 부위에 따른 차이가 없었다. 2. 부위별 미세인장접착강도를 비교하여 보았을 때 상아질 표층부에서의 미세인장접착강도는 레진의 접착 방식간에 차이가 없었으나, 심층부에서는 2군, 3군, 4군 및 1군의 순으로 나타났고(p<0.05), 치경부에서는 2군과 3군이 1군과 4군에 비하여 현저히 높았다(p<0.05). The purpose of this study was to evaluate the micro-tensile bond strength (μTBS) of four luting resin to regional dentin of human primary teeth. Dentin from non-carious primary molars were prepared from different regions(s, superficial dentin; d, deep dentin; c, cervical dentin), and divided into groups based on anatomical locations and types of luting resins(Scotchbond Multi-purpose: SB ; One-Step: as ; AdheSE Bond: ASE ; G-Bond : GB) : SB-s, SB-d, SB-c; OS-s, OS-d, OS-c; ASE-s, ASE-d, ASE-c ; GB-s, GB-d, GB-c. Luting resins were used according to the manufacturers' instructions, to bond Light-Core™ Core Build-Up Composite) to the exposed dentin specimens in the light-curing mode. After storage for 1 day, μTBS was tested at a cross-head speed of 1 mm/min. Data were analyzed with T-test and two-way ANOVA. The bonding interface and fractography analyses were performed with SEM. The results were as follows : 1. μTBS to superficial dentin was significantly higher than to deep dentin for SB(p<0.05). But there were no significant differences in regional μTBS among as, ASK GB(p>0.05). 2. There were no significant differences in μTBS to superficial dentin among each groups. But, in deep dentin, μTBS of SB-d was significantly lower than those of OS-d, ASE-d, and GB-d(p<0.05). μTBS of OS-d was significantly higher than those of GB-d(p<0.05), but there were no significant differences in μTBS of ASE-d. There were no significant differences among μTBS of ASE-d, OS-d, and GB-d.