• 대한공업교육학회지
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• 제35권2호
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• pp.1-24
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• 2010

이 연구의 목적은 공업계 고등학교에서 프로젝트 학습법에 의한 기계공작실습이 학생들의 직업기초능력 향상에 미치는 효과를 실증적으로 규명하여 이와 유사한 연구를 수행하고자 하는 현직교사 및 예비교사들에게 연구의 기초 자료를 제공하는 데 있다. 이 연구에서 관심을 둔 직업기초능력은 의사소통 능력, 정보활용 능력, 팀워크 능력, 문제해결 능력, 도구활용 능력, 책임감 및 자신감 영역이었다. 이 여섯가지 영역에 대한 사전, 사후 검사 결과는 통계적으로 유의미한 차이를 보여 주었다. 따라서, 전통적인 실습 방법보다 프로젝트 학습법의 적용이 공업계 고등학교 학생의 직업기초능력 향상에 효과적이었다는 사실을 확인할 수 있었다. 이 연구 결과를 기초로 공업계 고등학생의 직업기초능력 향상을 위해 그리고 후속연구의 질적 제고를 위해 몇 가지 제언을 하고자 한다. 첫째, 문제해결력, 의사소통능력, 정보활용능력과 같은 직업기초능력이 있는 인재들을 효과적으로 양성하기 위하여 다양한 교수학습 방법의 모색과 활용이 필요하다. 둘째, 공업계 고등학교학생의 직업기초능력 향상 프로그램의 효과성을 측정하기 위한 보다 객관적인 검사 도구의 개발이 요구된다. 셋째, 프로젝트 학습법은 학습자들의 전인적 직업기초능력을 함양하는데 긍정적인 영향을 미친다는 연구결과에 비추어볼 때, 공업계 고등학교의 수업개선을 위하여 적극적으로 연구해야 할 필요가 있다. 따라서 이러한 연구와 적용이 실질적으로 이루어지도록 하기 위하여 프로젝트 학습법에 대한 교원연수를 강화하고 다양한 지원이 수반되어야 할 것이다.

• Restorative Dentistry and Endodontics
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• 제21권1호
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• pp.87-105
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• 1996

The purpose of this study is to investigate the characteristics of the compositions and phases of amalgam alloys and amalgams by using EMPA and X-ray diffractometer. Each specimen was made from Caulk Fine Cut Clow copper lathe cut amalgam), Caulk Spherical (low copper spherical amalgam), Tytin (high copper unicorn position amalgam), Dispersally (high copper admixed amalgam) and Valiant (Palladium enriched amalgam). For preparing amalgam alloys, Tytin and Valiant were used as powder forms and the others were used as tablet forms after being polished with polishing machine. For preparing amalgams, each amalgam alloy and Hg were measured, and triturated by mechanical amalgamater according to user's instructions. After triturating, the triturated mass was inserted to cylindrical metal mold and simultaneously adapted by cylindrical condenser with same diameter and condensed by Instron universal testing machine with 80kg pressure & 1mm/min speed. Each specimen was removed from the metal mold and stored at room temperature for a week. The specimen was polished with the same polishing machine for amalgam alloy. For observation of microstructure and analysis of composition of amalgam alloys and amalgams, EMPA was used to get secondary electron images, backscattered images and characteristic X-ray images of Ag, Sn, Cu, Zn, Hg. To analyze compositions of amalgam alloys and amalgams, X-ray diffractometer was used. Amalgam alloys were scanned at the range of 2${\theta}$ of 30-$85^{\circ}$ and the speed of $4^{\circ}$/min with Cuka line and amalgams were scanned at the range of 2${\theta}$ of 28-$44^{\circ}$ and the speed of $4^{\circ}$/min with Cuka line. By comparing obtained d(distance between surfaces) and d of expected phases and atoms in amalgam alloys and amalgams in ASTM card, phases and atoms were identified. The results were as follows, 1. In Caulk Fine Cut amalgam alloy typical ${\gamma}$ phase was shown, and in amalgam, ${\gamma}$, ${\gamma}_1$ and ${\gamma}_2$ phases were observed. 2. In Caulk Spherical amalgam alloy ${\gamma}$, Ag, Cu and $\varepsilon$ phases were shown, and in amalgam ${\gamma}$, ${\gamma}_1$, ${\gamma}_2$ and $\eta$ phases were observed. 3. In Tytin amalgam alloy ${\gamma}$, Cu and $\varepsilon$ phases were shown, and in amalgam ${\gamma}$, ${\gamma}_1$, $\eta$ and $\varepsilon$ phases were observed. 4. In Dispersalloy ${\gamma}$, Ag, Cu and $\varepsilon$ phases were shown, and in amalgam ${\gamma}$, ${\gamma}_1$, $\eta$ and $\varepsilon$ phases were observed. 5. In Valiant alloy ${\gamma}$, Cu and e phases were shown, and in amalgam ${\gamma}$, ${\gamma}_1$, $\eta$ and $\varepsilon$ phases were observed.

• 에너지공학
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• 제18권1호
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• pp.49-55
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• 2009

금속의 수소취화는 수소를 사용하는 설비의 안전성을 위협하는 중요한 문제이므로, 수소 환경에서 금속의 취화평가법에 관한 연구의 필요성이 요구되고 있다. 수소사회를 대비하기 위하여 대용량의 수소공급방법에 관한 연구가 진행되고 있는데, 기존의 천연가스 배관을 통한 공급방안이 검토되고 있다. 본 연구에서는 배관 내부에 수소혼합가스가 흐르면 배관모재부 및 용접부의 손상이 우려되므로, 국내에 건설되어 운용되고 있는 X65 천연가스 배관의 모재부를 대상으로 수소취화 거동에 대하여 연구하였다. 재료의 수소침투는 전기분극법을 사용하였으며 강도평가에는 소형펀치시험법을 사용하였다. 수소장입량의 증가에 따라서 금속의 강도가 저하되는 현상이 발견되는 재료도 있으나, 본 연구에 사용한 X65강의 모재부에서 수소취화의 영향은 거의 나타나지 않았으므로 수소영향에 의한 X65강 모재부의 강도저하는 발생하지 않는 것으로 판단된다. 또한 소형펀치시험을 이용함으로써 금속재료의 수소취화에 의한 기계적 강도변화를 평가할 수 있었다.

• 대한간호
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• 제37권4호
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• pp.72-84
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• 1998

This study has been done for the purpose of testing the effects of education for women's health on the performance of health promoting behavior and self esteem of college women. The study was designed as simulated control group pretest-posttest design, the experimental group was composed 182 college women and the control group was composed 151 college women at D University in Seoul. The instruments used for this study were Health Promoting Behavior Scale developed by Walker et al(1987)were modified by Shin(1997) and Self Esteem Scale developed by Rosenberg(1965). The data were analyzed by chi-square test, t-test and ANCOVA using $SPSSIPC^+$ program. The results were as follows: 1. The result of the homogeneity test in terms of the demographic characteristics of two group showed that there were significant difference in major discipline($x^2=155.854$, p=.000), religion($x^2=6.325$, p=.011), and disease experience($x^2=3.949$, p=.046). 2. Hypotheses 1 that the college women who get women's health education will have a higher score of health promoting behavior than the college women who do not get women's health education was supported. The score of health promoting behavior between two group showed statistically difference(t=7.25, p= .000). Mer control of covariates(major discipline, religion, and disease experience), the score of health promoting behavior between two group showed statistically difference(F=31.817, p= .000). 3. Hypotheses 2 that the college women who get women's health education will have a higher score of self esteem than the college women who do not get women's health education was supported. The score of self esteem between two group showed statistically difference(t=4.91, p= .000). After control of covariates(major discipline, religion, disease experience), the score of self esteem between two group showed statistically difference(F=12.688, p= .000). The following suggestions are made based on the above results : 1) Replication of the research is needed to confirm effects of health education including the college man and various demographic differences. 2) More effective health education programs appropriate to subject need to be developed. 3) Nursing college or departments of nursing should make an effort to develop and carry out various health education program for health for all.

• 한국강구조학회 논문집
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• 제30권2호
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• pp.115-126
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• 2018

고강도 강재의 높은 항복비와 같은 특이한 물성에 대한 우려 등의 이유로 국내외 대표적인 강구조 설계기준에서는 강관구조에 고강도 강재를 적용하는 것을 금지하거나 제한하고 있다. 대부분의 설계기준에서는 강관의 항복강도가 355 또는 360MPa을 초과하는 경우 제시된 설계강도식을 사용할 수 없거나 강도저감계수를 통해 설계강도를 낮추어야 한다. 반면 이러한 제한사항에 대한 역학적 근거는 명료하지 않다. 또한 최근 저자들에 의해 수행된 X형 원형강관접합부에 대한 실험연구는 고강도강에 대한 규제가 과도하게 보수적일 수도 있다는 점을 지적한 바 있다. 본 연구에서는 고강도강 X형 원형강관접합부의 지관 압축 하에서의 거동을 더 자세히 분석하기 위해 실험에 이은 수치해석 변수연구를 수행하였다. 일반 강재부터 매우 항복강도가 높은 고강도 강재까지 넓은 범위의 강종을 고려하였다. 본 수치해석 연구에서도 현행의 고강도강 페널티가 매우 보수적이며 완화될 여지가 있음을 확인할 수 있었다. 또한 주관 축응력 하에서의 고강도강 접합부의 거동을 분석한 결과 현행 기준식이 고강도강 접합부의 주관 축응력에 의한 강도 감소 효과를 보수적으로 예측함을 확인하였다. 일반적으로 주관 축응력이 작용할 때 고강도강 접합부는 일반강 접합부에 비해 접합부 강도를 더 잘 유지하였다. 더불어 현행 기준식의 형태가 실제 접합부 거동을 정확히 표현하는 데에 한계가 있으며 개선될 여지가 있음을 지적하였다.

• 구강회복응용과학지
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• 제19권1호
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• pp.17-25
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• 2003

Treatment with implants of single tooth missing cases is both functional and esthetic. Although the success rate of single-tooth implant treatments is increasing, sometimes it makes some problems. Problems with single-tooth implant treatments include soft tissue complications, abutment screw fracture, and most commonly, abutment screw loosening, and these involve the instability of the dental implant-superstructure interface. This study investigated and compared dental implant screw joint micromotion of various implant system with external connection or internal connection when tested under simulated clinical loading, Six groups (N=5) were assessed: (1) Branemark AurAdapt (Nobel Biocare, Goteborg, Sweden), (2) Branemark EsthetiCone (Nobel Biocare, Goteborg, Sweden), (3) Neoplant Conical (Neobiotec, Korea), (4) Neoplant UCLA (Neobiotec, Korea), (5) Neoplant 5.5mm Solid (Neobiotec, Korea), and (6) ITI SynOcta (Institute Straumann, Waldenburg, Switzerland). Six identical frameworks were fabricated. Abutment screws were tightened to 32-35 Ncm and occlusal screw were tightened to 15-20 Ncm with an electronic torque controller. A mechanical testing machine applied a compressive cyclic load of 20kg at 10Hz to a contact point on each implant crown. Strain gauge recorded the micromotion of the screw joint interface once a second. Data were selected at 1, 500, 5,000, 10,000, 20,000, 30,000, 40,000 and 50,000 cycle and 2-way ANOVA test was performed to assess the statistical significance. The results of this study were as follows; The micromotion of the implant-superstructure in the interface increased gradually through 50,000 cycles for all implant systems. In the case of the micromotion according to cycle increase, Neoplant Conical and Neoplant UCLA system exhibited significantly increasing micromotion at the implant-superstructure interface (p<0.05), but others not significant. In the case of the micromotion of the implant-superstructure interface at 50,000 cycle, the largest micromotion were recorded in the Branemark EsthetiCone, sequently followed by Neoplant Conical, Neoplant UCLA, Branemark AurAdapt, ITI SynOcta and Neplant Solid. Internal connection system showed smaller micromotion than external connection system. Specially, Neoplant Solid with internal connection system exhibited significantly smaller micromotion than other implant systems except ITI SynOcta with same internal connection system (p<0.05). In the case of external connection, Branemark EsthetiCone and Neoplant Conical system with abutment showed significantly larger micromotion than Branemark AurAdapt without abutment (p<0.05).

• 대한치과기공학회지
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• 제39권2호
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• pp.75-82
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• 2017

Purpose: This study provided the basic data for selection the zirconia block and CAM by means of marginal fitness observations, flexural strength test and hardness test. Methods: Three dental zirconia blocks(ABCera, NaturaZ, ST98) and two dental milling machines(CAD/CAM MS, DWX-50) were used in this study. Metal abutment(diameter 10 mm, height 5 mm, inclined angle $3^{\circ}$ taper, 1 mm chamfer margin) was fabricated by Ti customized abutment, and then zirconia copings were fabricated for each ten specimens. Silicone replica technique was used to observe the marginal fitness of cross-sections with a stereomicroscope at ${\times}50$ magnification. The dental zirconia blocks was cut into 10 pieces each having a size of $25mm{\times}5mm{\times}1mm$, and fabricated according to the manufacturer's instructions, and flexural strength was measured using a universal testing machine. For hardness test, a micro Vickers hardness tester was used as it was in the flexural strength test. Statistical analysis was performed by one way ANOVA and post-test was performed by Scheffe test. Results: For marginal fitness of bucco-lingual axial, ZU group($59.7{\pm}10.3{\mu}m$) was the lowest, followed by RA, ZA, ZD, RD, RU. For marginal fitness of mesio-distal axial, ZU group($59.3{\pm}10.2{\mu}m$) was the lowest, followed by RA, ZA, RD, ZD, RU. One-way ANOVA showed statistically significant difference between groups(p<0.05). For flexural strength, ABCera block($718.0{\pm}57.2MPa$) was the highest, followed by NaturaZ, ST98. For hardness, ABCera block($1550.3{\pm}19.8Hv$) was the highest, followed by ST98, NaturaZ. There was no significant difference in flexural strength and hardness between blocks(p>0.05). Conclusion: Based on the results of this study, the type of dental zirconia block did influence the marginal fitness, and all dental zirconia blocks are expected to be suitable for clinical application. The highest flexural strength and hardness were ABCera block, and no statistically significant difference was observed.

• 대한치과보철학회지
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• 제44권5호
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• pp.642-653
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• 2006

Purpose : The purpose of this study was to investigate the effect of the output energy(voltage) of laser welding on the strength and properties of joint of cast titanium(CP Gr II) and titanium alloy(Ti-6Al-4V). Material and method : Cast titanium and its alloy rods(ISO6871) were prepared and perpendicularly cut at the center of the rod. After the cut halves were fixed in a jig, and the joints welded with a laser-welding machine at several levels of output voltage of $200V{\sim}280V$. Uncut specimens served as the non-welded control specimens The pulse duration and pulse spot size employed in this study were 10ms and 1.0mm respectively. Tensile testing was conducted at a crosshead speed of 0.5mm/min. The ultimate tensile strength(MPa) was recorded, and the data (n=6) were statistically analyzed by one-way analysis of variance(ANOVA) and Scheffe's test at ${\alpha}$=0.05. The fracture surface of specimens investigated by scanning electron microscope (SEM). Vickers microhardness was measured under 500g load of 15seconds with the optimal condition of output voltage 280V. Results : The results of this study were obtained as follows, 1. When the pulse duration and spot size were fixed at 10ms and 1.0mm respectively, increasing the output energy(voltage) increased UTS values and penetration depth of laser welded to titanium and titanium alloy. 2. For the commercial titanium grade II, ultimate tensile strength(665.3MPa) of the specimens laser-welded at voltage of 280V were not statistically(p>0.05) different from the non-welded control specimens (680.2MPa). 3. For the titanium alloy(Ti-6Al-4V), ultimate tensile strength(988.3MPa) of the specimens laser-welded at voltage of 280V were statistically(p<0.05) different from the non-welded control specimens (665.0MPa). 4. The commercial titanium grade II and titanium alloy(Ti-6Al-4V) were Vickers microhardness values were increased in the fusion zone and there were no significant differences in base metal, heat-affected zone.

• 대한조선학회논문집
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• 제38권1호
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• pp.99-107
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• 2001

어선 제작시 어선의 고속화 및 어로작업 등에 의한 내구성을 향상시키기 위해 선각재질이 가볍고, 강도, 화재 및 해수의 부식 등에 뛰어난 재료의 사용이 요구되어지고 있다. 이러한 어선으로서는 크게 FRP어선과 Al어선으로 대별할 수 있다. 그러나 FRP어선은 가볍고 강도는 우수하나 인화성이 높아서 열에 매우 약하고 선박 제작 과정에 있어 인체에 해로운 유해성분이 발생할 뿐만 아니라, 폐선의 경우 산업폐기물로써 환경 오염에 큰 영향을 미치고 있다. 그런 반면에, Al어선은 FRP어선의 단점을 보완할 수 있는 재료로써, 고강도 및 경량화의 효과를 낼 수 있고, FRP어선보다 인화성이 낮아서 열에 강하고, 내구성이 높아 해수의 부식방지에 뛰어나므로 Al 어선의 개발이 시급한 실정이다. 그러나, 알루미늄 합금은 용접성이 좋지 않고 용접변형 및 균열이 발생하고, 건조 비용이 비싸다는 단점이 있다. 따라서, 본 연구에서는 Al 합금 접합시의 문제점 해결방안으로 용접이음부의 새로운 형상을 개발하고 개발한 신형상에 대한 역학적 거동을 규명하고자 하였다. 이를 위해, 먼저 평판 이론을 이용하여 구조부재를 단순화하여 평판, 보강판, 신형상에 대하여 해석함으로써 강도를 비교 검토하고, 이러한 결과를 토대로 자체 개발된 용접열전도 및 용접열응력 수치해석 프로그램을 사용하여 평판과 신형상의 온도분포, 용접잔류응력, 인장, 압축시의 강도를 수치시뮬레이션을 통하여 비교, 검토하였다. 또한, 인장 시험편을 제작하여 실험을 통하여 강도를 비교함으로써 신형상에 대한 적용 가능성 및 역학적 우수성을 입증하고자 하였다.

• 한국작물학회:학술대회논문집
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• 한국작물학회 2017년도 9th Asian Crop Science Association conference
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• pp.204-204
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• 2017

In recent years the growth rates of world agricultural production and crop yields have slowed because of rapid urbanization but the agriculture mechanization implies the use of various power sources and improved farm tools and equipment to enhance the efficiency of utilization of various crop input. Therefore the current study was conducted to investigate the growth characteristics of seedlings treated with plant growth regulators for the production of seeds suitable for mechanical formulations of soybeans and red beans. The seeds of Uram bean and Arary red bean were sown in 128 well plug tray as the testing varieties. Three growth inhibitors such as 0.05% hexaconazole, prohexadion-calcium, and 0.1% diniconazole were treated and fifteen representative plants were collected from each treatment at 2, 5, 7, 13, 16, 17, 19, and 20 days interval after treatment. The collected plants were examined for the growth atributes such as plant height, root length, leaf area and chlorophyll. The growth promoter was treated at the 13th day after treatment with growth inhibitor and treated with 0.1% concentration of Pomina ($GA_{4+7}$ 1.8% + 6-benzylaminopurine 1.8%) and Nonaji (gibberellic acid 2% + $GA_{4+7}$ 2%). Initially the growth data was recorded to examine the effect of growth inhibitor, while after treatment with growth promoters, the growth attributes were recorded at 4th and 7th day. As a result of measuring the growth parameter of soybean, the inhibitory effect was shown in the aerobic treatment at the ground level at the 7th day after treatment. At the 4th day of growth promoting agents treatment, the stimulation effect of non - treated plants was greater than that of formalin treatments. As a result of measuring the growth attributes of red bean, In the latter part of the growth, at the 4th day after the growth promoter treatment. This study was able to confirm the effective growth regulators and treatment periods for each crop, and it was possible to control the growth of seedlings. Based on these results, it can be expected that the basis of seedling production technology of crops which is necessary for sowing and transplantation mechanization of agriculturle field can be established.