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Improvement of Thermoplastic Forming Ability of Ti–Zr–Ni–Cu Metallic Glass by Addition of Sn
Yeong‑Seong Kim,Woo‑Chul Kim,Won‑Tae Kim,Do‑Hyang Kim 대한금속·재료학회 2021 METALS AND MATERIALS International Vol.27 No.6
Ti–Zr–Ni–Cu metallic glass attracts an attention as a precursor of superelastic alloy that can be deformed into nm scalecomplex shapes. However, since the thermal stability of Ti–Zr–Ni–Cu metallic glass in the supercooled liquid region is quitelow, application of thermoplastic forming is limited. Therefore, in the present study, the effect of Sn addition on thermoplasticforming ability of Ti–Zr–Ni–Cu metallic glass has been investigated. Sn containing (Ti35Zr15Ni35Cu15)99Sn1 metallic glassexhibits longer incubation time before onset of crystallization than Ti35Zr15Ni35Cu15metallic glass, resulting in significantimprovement of thermoplastic forming ability. The crystallization behavior changes from three-dimensional growth of saturatednuclei to three-dimensional growth with constant nucleation rate with the addition of Sn. The overall activation energyfor crystallization of (Ti35Zr15Ni35Cu15)99Sn1 metallic glass is higher than that of Ti35Zr15Ni35Cu15metallic glass, indicatingthat the thermal stability of metallic glass is improved by addition of Sn. Because nuclei are continuously generated duringthe crystallization in (Ti35Zr15Ni35Cu15)99Sn1, the average grain size is much smaller than that in Ti35Zr15Ni35Cu15.
분자선 에피탁시로 Si 기판 위에 성장한 GaAs/Ge 에피층의 특성
우용득,이해익 우석대학교 부설 기초과학연구소 1997 기초과학연구소 논문집 Vol.2 No.-
Properties of GaAs/Ge epilayers grown using two step growth method on Si substrates by molecular beam epitaxy(MBE) are investigated using scanning electron microscopy(SEM), transmission electron microscopy(TEM), double crystal X-ray diffraction(DCXD), photolumin escence(PL) spectroscopy and Raman spectroscopy. PL. Raman and DCXD results show that the GaAs epilayer grown by two step growth method has best crystallinites. Because of the high temperature growth in two step growth method has an annealing effect upon the inital prelayer and the Ge buffer layer, resulting in the suppressed dislocatin initation.
산성강하물이 지표수의 산성화에 미치는 영향 Ⅱ: 컬럼연구 및 현장조사
김영관,우경식 江原大學校 附設 環境硏究所 1997 環境硏究 Vol.14 No.-
토양층과 모암층에서의 산성우에 대한 중화능력을 평가하기 위하여 인공강우를 이용한 컬럼실험을 실시하였으며 토양을 이루고 있는 모암 특성의 차이에 의한 산성강하물의 환충효과를 비교하기 위하여 연구지역내의 모암의 조성광물에 차이가 있는 두 개의 골짜기를 선정하고 골짜기에 흐르는 지표수의 pH를 1996년 5월부터 1996년 10월까지 측정하였다. 컬럼실험에서 사용한 인공강우는 증류수에 황산과 질산을 적절히 첨가하여 pH를 각각 3,4, 및 5로 조절하였으며 컬럼유출수의 주요 양이온과 음이온을 측정하였다. A층위와 B층위의 양이온 교환용량(CEC)은 각각 9.68 meq/100g과 6.16 meq/100g 이었으며 인공강우의 살포시 컬럼유출수의 pH는 중간층토양에서보다 양이온 교환용량이 큰 표층토양에서 더 크게 나타났다. 컬럼유출수에서의 Ca^(2+), Mg^(2+), Na^(+)의 합이 점차로 감소하여 지속적인 산성우는 토양의 양이온 교환용량을 감소시키는 것으로 나타났다. 현장조사결과에 따르면 골짜기의 하류로 내려옴에 따라 지표수의 pH는 계속 증가하여 하류로 흐르는 과정에서의 완충효과를 나타내었다. 이러한 완충효과는 모암의 조성광물중 kaolinite와 illite이외에도 smectite를 함유하고 있는 골짜기에서 더 크게 나타나는 것이 특징적이었다. 이 결과는 토양층 뿐만 아니라 모암이 산성우의 완충용량을 가지고 있음을 나타내었다. A column study using artificial acid rain was conducted to evaluate the buffering capacities in soil layer and host rock. In an effort to compare the effect of composition of host rock, two valleys of which compositions of host rock are different were chosen within the study area and the pHs of the water flowing in the valleys were measured from May, 1996 to October, 1996. The pHs of the artificial acid rain prepared by adding appropriate amounts of both sulfuric and nitric acids to distilled water were 3,4,and 5, and the column effluents were analyzed for major cations and anions. The cation exchange capacities(CECs) of A Horizon and the B Horizon were 9.68 and 6.16 meq/100g, respectively. Compared to the B Horizon, the pH in the column effluent of A Horizon with larder CEC was higher. The sums of Ca^(2+), Mg^(2+) and Na^(+) in the column effluents gradually decreased, indicating the loss of CEC by acid rain. The field study showed that pHs of the surface water in the valleys increased as the water flows downwards. The magnitude of this buffering capacity was greater for the valley in which smectite in addition to kaolinite and illite was a weathered product of host rocks. This also indicates that host rock as well as soil layer retains the buffering capacity.
산성강하물이 지표수의 산성화에 미치는 영향 Ⅰ: 현장 조사
김영관,이동석,김만구,우경식 江原大學校 附設 環境硏究所 1997 環境硏究 Vol.14 No.-
Effects of acid deposition on the acidification of surface water over a short period were studied during June~October, 1995. A reservoir located in Chunchon, Kangwondo was selected for this study because this reservoir had received little man-made pollutants. Geological survey within the study area was carried out and the pH of a small and shallow stream flowing from the mountain valley down to the reservoir was monitored. Rainfall was measured by using a rain gauge and the precipitation was collected by automatic precipitation sampler. During the study period, rain pH was in the range of 3.81~5.77 with an average of 4.8. The EC was in the range of 8~189㎲/cm with an average of 10.6㎲/cm. Ionic composition of the rainfall showed that, of the anions, deposition of SO₄^(2-) was highest with 3,119.7 kg/㎢, and is was NH^(4+)with 1,053.2kg/㎢ for cations. The surface water pHs were maintained neutral or weak basic, representing little evidence of acidification regardless of the acidic rainfall pH. Every time of sampling, however, the pHs exhibited increasing tendency as elevation of measuring site of the stream become lowered, which indicated the impacts of acid-base reactions by acidic or basic substances during travel of water downstream. This result suggested the necessity of further research to determine the respective buffering capacity of soil and underlying rocks. 산성강하물이 단기간에 걸쳐 지표수의 산성화에 미치는 영향을 조사하기 위하여 1995년 6월 부터 10월까지 외부오염원이 거의 없는 강원도 춘천시에 위치한 저수지를 선정하여 인구를 수행하였다. 연구지역 일대의 지질을 조사하고 산골짜기에서 저수지로 흐르는 작고 얕은 하천의 수질을 분석하였다. 강우량은 우량계를 이용하여 측정하였고 강하물은 자동포집기를 이용하여 포집하였다. 연구기간동안의 강우의 pH범위는 3.81~5-77로 평균 4.8을 나타내었으며 전기전도도(EC)sms 5~189㎲/cm로 평균 10.6㎲/cm를 나타냈다. 음이온 중에서는 SO₄^(2-)의 강하량이 3,119.7kg/㎢로 가장 많았고, 양이온 중에서는 NH^(4+)가 1,053.2kg/㎢로 가장 많았다. 지표수의 pH는 중성 또는 약염기성으로 강우의 pH가 산성이었음에도 지표수의 산성화 현상은 관찰되지 않았다. 그러나 골짜기에서 흐르는 하천수를 측정할때마다 측정지점의 고도가 낮아질수록 pH값은 증가하는 경향을 나타내어 물이 하류로 흘러가는 동안에 일어난 산성 또는 염기성물질로 인한 산염기반응의 영향을 보여주었다. 이 결과는 토양의 완충능력과 모암내에서의 중화능력을 각각 구별하여 조사할 필요성을 제시하였다.
유산소 리듬 운동프로그램이 노인의 혈압, 심박수 및 생활만족도에 미치는 효과
우선혜,김효정,박영숙 대한보건협회 2001 대한보건연구 Vol.27 No.3
The purpose of this study was to test the effects of aerobic rhythmical exercise program on blood pressure, pulse and the life satisfaction of the elderly. This quai-experimental study was designed as a non-equivalent control group pretest-posttest study. The subjects were 36 subjects(experimental group: 19 subjects, control group: 17 subjects), aged between 65 and 73 years who have normal cognition, sensory function and cerebellum function. Aerobic rhythmical exercise program was developed on the basis of aerobic exercise, Korean tradititional dance and music by the author. The blood pressure, pulse rate and life satisfaction were measured prior to and following the experimental treatment. Data were analyzed with x^2-test, t-test, mean, standard deviation, percentage of change and ANCOVA test using SAS program. The results were as follows. 1. There was no significant difference of systolic blood pressure between experimental and control group following the aerobic rhythmical exercise program(F=1.39, P=0.247). 2. The diastolic blood pressure of the experimental group was significantly lower than that of control group following the aerobic rhythmical exercise program(F=2.96, p<0.1). 3. There was no significant difference of resting heart rate between experimental and control group following the aerobic rhythmical exercise program(F=0.07, P=0.793). 4. The life satisfaction of the experimental group was significantly higher than that of control group following the aerobic rhythmical exercise program(F=9.94, p<0.01). On the basis of the above findings, aerobic rhythmical exercise program is effective in reducing diastolic blood pressure and promoting life satisfaction of the elderly. Thus, this program can be recommended as an effective nursing intervention for the elderly.
鄭宇珪,孔榮植,金哲壽,梁運眞 경남대학교 환경문제연구소 1996 환경연구 Vol.18 No.-
1990년 7월부터 1996년 8월까지 16회에 걸쳐 慶南 陝川郡 龍州面 박실지와 연당지 및 그 周邊 地域의 水生植物과 植物相을 조사한 결과는 다음과 같았다. 1. 조사된 總 植物은 38目 107科 287屬 365種 1亞種 61變種 3品種 總 430種類로 구성되었다. 2. 이들 중 水生植物이 11目 22科 41種 10變種 1品目 總 52 種類 12.1%이고, 挻水植物 25種類 5.8%, 浮葉植物 15種類 3.5%, 沈水植物 9種類 2.5%, 浮生植物 3種類 0.8%였다. 3. 陸上植物은 36目 92科 269屬 324種 1亞種 51變種 2品種 總 378種類 87.0%였고, 이들 중에는 濕生植物이 50種類 13.2%, 水邊植物이 328種類 86.8%였다. 4. 박실지의 溜池에서 優占種은 마름, 準優占種은 줄이었고, 연당지에서의 優占種은 줄이었고 準優占種은 연이었다. 5. 희귀식물인 가시연꽃과 통발, 북방분자인 돌단풍과 도루박이 및 최근에 국내에 분포하는 것이 확인된 민초피나무의 분포가 논의되었다. The flora and distribution of hydrophytes and terrestrial plants from Paksil and Yundang swamp and their adjacent area in Hapchon-hun. Kyongsangnam-do were investigated at sixteen times from July. 1990 to August. 1996. The flora was composed of 38 orders. 107 families. 287 genera. 365 species. 1 subspecies, 61 varieties, and 3 forma, total 430 taxa. Among them, the vascular hydrophytes were composed of 11 orders. 22 families, 31 genera, 41 species, 10 varieties, and 1 forma, total 52 taxa. 12.1%. These were composed of 25 taxa emerged plants. 15 taxa floating-leaves plants. 9 taxa submerged plants, and 3 taxa free-floating plants. The terrestrial plants were composed of 36 orders. 92 families. 269 genera. 324 species. 1 subspecies. 51 varieties, and 2 forma. total 378 taxa. 87.9%. Among them, the hygrophytes and water side plants were 50 taxa, 13.2% and 328 taxa, 86.8%. In Paksil swamp dominent species was Trapa japonica and subdominent was Zizania latiforia on the whole. In Yundang swamp dominent species was Zizania latiforia and subdominent species was Nelumbo nucifera on the whole. The distribution of Euryale ferox. Scirpus radicans. Acerphyllum rossii. Utricularia Japonica. Xanthoxylum piperitum var. inerme. were discussed. Also the work protection of Paksil swamp were discussed.
이창우,함영민,김정환,현성호 韓國火災 ·消防學會 1998 한국화재소방학회논문지 Vol.12 No.2
가축사료 분진의 열적 안정성 실험결과 본 연구에서 사용한 시료 입도의 경우 발열개시온도 및 발열량에는 별 차이가 없었으나, 승온속도가 증가함에 따라 발열개시온도가 낮아지고, 입도가 미세해질수록 분해열이 증가함을 알 수 있었다. 한편, 분위기 기체를 조연성 기체인 O_2로 사용할 경우 불활성 기체인 N_2를 사용하는 경우보다 발열개시온도는 현저히 낮아지며, 반면에 발열량도 20배 이상 증가하였다. 또한 본 연구에서 사용한 시료중 비교적 미세입자가 대기중에 부유하기 쉽고, 외부에서 점화에너지가 주어질 경우 공기중의 산소와 쉽게 순간적으로 반응하여 폭발하는 것을 볼 수 있다. 본 연구에서의 시료입도중 80/100 mesh의 경우 평균 최대폭발압력은 6.88 Kgf/㎠ 로 구해졌다. According to the results for thermodynamic stability of feed-stuff dust, there are little change of initiation temperature of heat generation and heating value for used particle size. But initiation temperature of heat generation decreased with high heating rate whereas decomposition heat increased with particle size. Using the supporting gas, O_2, initiation temperature of heat generation decreased remarkably than using the inert gas, N_2, and heating value increased as twenty times under the same condition. When the ignition energy is given from the outside, used fine particle which can float in the air easily reacted tremendously with oxygen. Average maximum explosion pressure was 6.88 Kgf/㎠ for 80/100 mesh.
學業 成積에 影響을 주는 家庭環境과 自我槪念에 관한 硏究
金英雨,李達錫 조선대학교 사범대학 부설 교과교육연구소 2002 敎科敎育硏究 Vol.23 No.1
The purpose of this study was to examine whether self-conception and home-environment relate positively with academic achievement. In order to fulfill the purpose of this study the research questions of the study were established as follows: 1) Dose home-environment(the status environment. the process environment) and self-conception correate? 2) Does the subvariables of the status environment, that is, the degree of parent's education, monthly income, job, residence and self-conception correlate? 3) Does the subvariables of the process environment, that is, the acceptance-reject, the autonomy-control, the achievement press and self-conception correlate? 4) Does the status environment, the process environment and total home-environment effect the academic achievement? 5) Are there any difference among self-conception according to level of academic achievement? The subjects of the study were the second grade from 4 high schools in Kwang Ju. The total number of subjects were 298 students. The data were gathered from self-conception inventory(Kim Gi-Jung, 1984), the home-environment inventory(Kim Gi-jung, 1984) and the mean of academic achievement admitted by each high school administration. The results were as follows: 1) Home-environment strongly effects self-conception, especially the process home-environment stronger effect self-conception than the status environment. 2) There is relationship between the status environment and self-conception with r=.65. The higher is the score of status environment, the higher is academic self-conception and moral self-conception of high school students. 3) In relationship coefficient (r-.84) is higher than the relationship between the status environment and self-conception(r=.65). 4) The process environment is important than the status environment. So parent's caring attitude and expectation is more important than home accomodations and furniture. 5) Comparing the level(high, middle, low) of academic achievement with self-conception, academic, moral, home and total self-conception of high level is higher than middle and low of academic achievement.
배영호,이현우,홍성태,서기영,차영문,권순걸 慶南大學校 附設 工業技術硏究所 1992 硏究論文集 Vol.10 No.-
이 논문은 MOSFET로 구성된 등가 Half-bridge형 고주파공진형 인버어터에 대해 기술하고 있다. 시분할 방식에 의한 게이트회로를 구성하여 구동함으로써 출력단에는 두개의 인버어터에서 동작되는 순시위상이 합성되어 있어 나타나므로 부하단 출력주파수는 소자의 수위칭주파수에 대해 두배가 되고 수위칭 손실이 경감되어 소자의 평균전류가 증가한다. This paper proposes a high frequency resonant inverter consisting of equivalent half bridge model using MOSFET. In this paper time-sharing control method is applied. as a result the output frequency is two times as high as switching frequency of device and average current of device is increased because of decreasing switching loss.
斷熱 氣-液 流動化 再循環 反應器에서 離脫된 溫度의 制御
咸榮敏,洪英浩,李暢祐 단국대학교 1994 論文集 Vol.28 No.-
This study was carried out to investigate the effect of the control action, recycle ratio and the position(top, middle and bottom) of set temperature and controlled temperature within the reactor on temperature control in adiabatic ebullated recycle reactor when the disturbance was occured. Estimation of th solution were performed numerically using the finite difference method. It was assumed that heat of reaction and the physical properties(density, heat capasity and viscosity…. etc) of the flowing fluid are not nearly varied within the reactor. It was shown that the response time was shorter at higher recycle ration and the PI-control for middle point temperature of the reactor as controlled temperature was available.