• Journal of Powder Materials
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• v.4 no.4
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• pp.283-290
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• 1997

$Ti_5Si_3$ intermetallics containing 0-6 wt% of Cu were made by reactive sintering (RS) under vacuum using elemental powder mixtures (Process 1), electro-pressure sintering (EPS) using RS'ed materials (Process2), and EPS using elemental powder mixtures (Process 3). Relatively low dense titanium silicides were gained by process 1, in which porosity decreased with increasing Cu content. For example, porosity changed from 42 to 19.4% with the increase in Cu content from 0 to 6 wt%, indicating that Cu is a useful sintering aid. The titanium silicides fabricated by Process 2 had a higher density than those by Process 1 at given composition, and porosity decreased with increasing Cu content. For example, porosity decreased from 38 to 6.8% with the change in Cu content from 0 to 6 wt%. A high dense titanium silicides were obtained by Process 3. In this Process, porosity decreased a little by Cu addition, and was almost insensitive to Cu content. Namely, about 9 or 7% of porosity was shown in 0 or 1-6 wt% Cu containing silicides, respectively. The hardeness increased by Cu addition, and was not changed markedly with Cu content for the silicides fabricated by Process 3. This tendency was considered to be resulted from porosity, hardening of grain interior by Cu addition, and softening of grain boundary by Cu-base segregates. All these results suggested that EPS using elemental powder mixtures (Process 3) is an effective processing method to achieve satisfactorily dense titanium silicides.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.34 no.10
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• pp.1367-1375
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• 2010

In this study, optimization of the process parameters of the resistance spot welding of a sheet of aluminum-coated boron alloyed steel, 22MnB5, used in hot stamping has been performed by a Taguchi method to increase the strength of the weld joint. The process parameters selected were current, electrode force, and weld time. The heating temperature and heating time of 22MnB5 are considered to be noise factors. It was known that the variation in the thickness of the intermetallic compound layer between the aluminum-coated layer and the substrate, which influences on the formation of nugget, was generated due to the difference of diffusion reaction according to heating conditions. From the results of spot weld experiment, the optimum weld condition was determined to be when the current, electrode force, and weld time were 8kA, 4kN, and 18 cycles, respectively. The result of a test performed to verify the optimized weld condition showed that the tensile strength of the weld joint was over 32kN, which is considerably higher than the required strength, i.e., 23kN.

• Journal of Christian Education in Korea
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• v.63
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• pp.347-376
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• 2020

This study suggests the direction and practice of Christian education through ecological Christian spirituality required in front of the ecological crisis. Environmental destruction and ecosystem problems are recognized as a serious crisis that can threaten human survival. As a result, the development of material civilization, which humanity has taken for granted, has been questioned, and changes in human consciousness and thoughts at the root of the ecological crisis have become inevitable. The crisis of civilization demands a new spirituality, and the spirituality required in front of the ecological crisis must be a life-friendly spirituality. The discourses on the ecological crisis that have emerged since the 1970s provide a fundamental perspective on the ecological crisis. Ecological spirituality such as 'immanence', 'interrelationship', 'community', 'healing and emancipation', and 'sustainability' are concepts that can understand and aggregate the discussions of the various discourses above. Based on this, this paper examines Christian ecological spirituality by dividing it into the areas of God, humans, and body. Through this, the Christian education was proposed as a practical place for self-depreciation for a simple life through the understanding of God, who emptied himself out of the transcendent God who reigns over all things, shared the pain of all things, maintained all things together, and lived in them. There, meditation and hospitality can be a place of practical Christian education where one can enrich one's inner self for a simple life. Christian education was proposed as a place of holistic knowledge through ecological Christian spirituality that emphasizes the spirituality of the body from dichotomous thinking that belittles the body. There, the Holy Communion is important as a place where both holistic education to restore the spirituality of the body and ecological education can be held at the same time. Through this, I hope that Christian education will be a place of education not only for the reason but also for the holistic knowledge of Christ and for learning how to 'together' with the ecosystem and neighbors.

• Journal of Embryo Transfer
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• v.20 no.1
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• pp.25-33
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• 2005

This study is a part of research that development of effective genetic resources preservation system using the in vitro spermatogenesis, in vitro insemination and culture system. We aimed for establishment of in vitro culture system with in vitro activated porcine oocytes. The porcine oocytes were matured for 48 hours in $TCM199+10\%$ FCS and activated with $7\%$ ethanol. The activated oocytes were cultured for 7 days in $TCM199+10\%$ FCS or $NCSU23+0.4\%$ BSA medium. The activated oocytes were not developed to the blastocyst stage in $TCM199+10\%$ FCS medium. However in $NCSU23+0.4\%$ medium, those were developed to blastocyst with $3\%$ of treated oocytes. We extended maturation duration of porcine follicular oocytes fur 48, 52, 56, 60, 64, 68, and 72 hours and activated with $7\%$ ethanol and cultured using $NCSU23+0.4\%$ BSA medium. The six percents of activated oocytes were developed to blastocyst in 48 hours and $10\%$ in 52 hours with comparatively low rates suggested to be not fully activated by regenerated MPF. Maturation durations from 56 hours to 68 hours supported to develop upto $11.9\~18.3\%$ of blastocysts. However the developmental rate was declined to $7.2\%$ at 72 hours of maturation duration because of cytoplasmic deterioration. The assumed time window for activation will be $56\~68$ hours of maturation duration. When the matured oocytes were activated with electric pulse of 1, 1.2, 1.4, 1.6, 1.8 and 2.0kV/cm for $80{\mu}s$, although appling the electric current once was not enough for activation, appling twice with 1.6kV/cm for $80{\mu}s$ was shown the highest developmental rate with $11.3\%$. When those were compared with activating methods, $15.7%$ of blastocyst rate was obtained in the $7\%$ ethanol. That was higher than those in electric pulse with $9.5\%$ and calcium ionophore method with $5.8\%$. In this experimental condition, the $7\%$ ethanol treatment was the most effective method for activating porcine oocytes.

• Journal of Christian Education in Korea
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• v.67
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• pp.301-337
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• 2021

The researcher looked at the differences in views and various controversies surrounding Korean youth sexuality education in the wake of the Nth Room incident, which had a great impact on modern Korean society. Sex education for adolescents in Korea can be divided into public sex education through school sex education and the Youth Sexuality Center, and conservative/traditional Protestant sex education. Public sex education is partly influenced by feminist sexual ethics and comprehensive sex education abroad. Based on gender sensitivity and the right to sexual self-determination, four major projects are prevention of sexual harassment, prostitution, sexual violence, and domestic violence. However, the school sex education standard was criticized for stereotypes of gender roles and gender-discriminatory content, reinforced distorted myths about sexual violence, and exclusion of sexual diversity and various family types. Conservative/traditional Protestantism is based on the normal family ideology such as bisexual marriage, premarital chastity, and sexual ethics recognized only within marital relationships. It is a form of confrontation with public sex education while strongly opposing it. The researcher first analyzed the characteristics of public sex education, conservative/traditional Protestant sexual ethics and sex education, feminist sex ethics and sex education, and overseas youth sex education, respectively, while composing the curriculum for Korean youth sexuality education. And as a more fundamental solution to youth sexuality education, I pointed out that there are limits to asceticism, premarital chastity, gender sensitivity and sexual self-determination education, and found an alternative to the concept of body and sex in feminist theology. The researcher pointed out that it is necessary to reconceptualize the body and sex under the recognition that the most fundamental cause of distorted sexual culture is dualistic sex and understanding the body, centering on the research of various feminist theologians. And this was conceptualized into three concepts: holistic sexuality, mutual solidarity understood in relationships with others, and sexuality as a spirituality that extends to the global community. And with each curriculum, 1) Holistic Sexuality: Breathing, Narrative, Making the Shape of One's Body and Mind 2) mutual solidarity : Feeling the Breath of Others, Media Literacy through Conscientization, Sending a Good Wind 3) Sexuality as a spirituality that extends to global concern: It was proposed to pay attention to nature and to co-cultivate it, to listen to the earth's moans and create a new way of life, and to write a prayer with the earth and fellow living beings.

• Proceedings of the KWS Conference
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• 2009.11a
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• pp.119-119
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• 2009

인버터 DC 저항용접의 적용성 증대 : 인버터 DC 저항용접 공법이 SPOT, PROJECTON, SEAM, BUTT 등의 공정에 다양하게 적용되어 저항용접 현장에서 고효율, 친환경적 용접 환경을 만드는데 일조 하고 있다. 특히 자동차의 경량화, 충돌내성 증대, 진동 및 내구성 증대, 공간활용 극대화, 새로운 Design 개념 적용 등의 산업전반에 걸쳐 나타나는 신 Trends로 고 장력 철재의 적용 범위가 확대되고 HSS(High Strength Steel), EHSS(Extra High Strength Steel), UHSS (Ultra High strength Steel ; Hot - Formed Steel )등 다양한 철판의 SPOT 저항용접이 필요하게 되었다. 기존의 AC 단상용접의 전력 특성 상 통전 중 무 통전 시간 과 높은 PEAK 전력, 단상 대 전력 소모로 인한 전력 DROP 등의 문제로 인하여 신소재의 용접 시 매우 많은 Spatter가 발생하고, 높은 용접품질의 확보가 어려워 지므로 이를 대체하기 위한 공법으로 MFDC ( 인버터 DC 저항용접공법 )이 적용되고 있다. 인버터 DC 저항용접의 적응제어 : MFDC라는 높은 효율의 용접 전력원이 확보 됨에도 불구하고 용접현장에서는 원 자재, 도금 등의 품질 산포, 프레스 물의 가공산포, 공기압 산포, 전극 과열 및 마모 등의 요인에 의하여 저항용접 산포가 발생하고 있다. 이는 인위적인 조작이 어렵고 불규칙적이며, 어디서나 산재하고 있는 문제이다. 이를 용접전력 제어 법으로 개선하여 일정한 용접성을 확보하기 위한 노력이 적응제어 기법이다. 정 전류, 정 전력 제어는 정량 제어로 용접 물을 비롯한 용접부의 변화와는 관계없이 설정된 일정량의 전력을 공급하기만 하는데 반하여 적응제어는 적절한 용접 작업 시의 용접 물의 상태, 전극의 가압, 표면 상태 등에 따른 변화 페턴을 기억하고 이후 진행되는 용접에 대하여 정상 페턴과의 차이를 감지 이를 보상하므로 고품질의 용접성을 보장하는 제어기법이다. 따라서 다양한 용접 산포 유발 요인에 의해 용접부의 변화가 발생한다 하여도 그 변화를 감지 하고 적절한 용접전력을 공급한다면 고품질의 용접성을 확보하는데 유용한 공법이 될 수 있다. 인버터 DC 저항용접의 SPC 관리 : SPOT 용접 시 획득할 수 있는 다양한 파라메터에 대하여 모니터링 하고 이 자료를 data 화 하여 품질 관리에 응용하게 되면 양산라인에서 반복적으로 발생되는 문제점을 확인 할 수 있고 이를 통계적 방법으로 추적 개선해 나간다면 용접 불량 감소 및 생산성 향상에 도움이 되며 작업자의 공정 능력 향상 및 기업의 기술축적에도 높은 기여를 할 수 있을 것이다. 용접 적응제어와 다양한 파라메터 모니터링이 한 system에서 이루어 질 때 높은 용접성 확보와 불량률 감소, 원가절감, 생산성 향상 등의 효과가 극대화 될 것이다.

• Korean Journal of Materials Research
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• v.9 no.7
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• pp.680-687
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• 1999

Fe-Al intermetallic compounds were manufactured by using the field-activated combustion synthesis process. Effects of chemical composition(Fe:Al= 3: 1,2:1, 1:1, 1:2, 1:3), Compaction pressure(150, 250, 350MPa) and electrical resistance on the reaction were investigated in this system. As the molar ratio of Al, compaction pressure and electric field increased, the combustion temperature and velocity were increased. The influences for reaction with current adjust way were investigated in this system. But in the absence of a electric field, the reaction could sustain a nonsteady combustion wave and was not completed. The reaction products were characterized with X-ray, SEM and EDXS to determine the structure and composition.

• Journal of the Society of Naval Architects of Korea
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• v.32 no.1
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• pp.83-93
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• 1995

A numerical and experimental investigation on the flow characteristics in the rectangular duct of an MHD propulsion system has been carried out. In numerical analysis, three-dimensional, steady-state, viscous, incompressible electrically conducting fluid flow under the influence of uniformly applied magnetic and electric fields was treated using a finite-difference technique. It was found from the numerical study that when the Lorentz force is weak, the typical parabolic velocity profile under a laminar flow condition changes to an M shaped profile near the electrode region and that the pressure increases linearly from the inlet toward the outlet of the MHD duct under constant electro-magnetic field. In experiment, thrust of the MHD propulsion system can be controlled easily by varying electrode current. The measured pressure gradient along the MHD duct is proportional to the Lorentz force, which is in agreement with the numerical results.

• Korean Journal of Materials Research
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• v.8 no.7
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• pp.584-590
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• 1998

The microstructures of finely distributed Si-phases in $\beta$-$FeSi_2$ thermoelectric matrix, were produced by heat-treating the melt-cast ingots of single $\alpha$-$Fe_2Si_5$ phase at 730~85$0^{\circ}C$ for 4~20 hours, or by resistance-hot-pressing the mechanically alloyed powders ordinarily consisting of $\varepsilon$-FeSi and Si phases at 760~85$0^{\circ}C$ for 10 minutes of composition. $(Fe_{0.98}Mn_{0.02})_xSi_2(x{\leq$}1) The size and interspacing of dispersed Si-phases were able to control within a range of 0.05~0.27$\mu\textrm{m}$ and 0.2~0.6$\mu\textrm{m}$ by variations of heat treatment temperature and sintering temperature as well as the composition. respectively. The dispersion of Si- phases was expected to be effective for the reduction of thermal conductivity responsible for the increment of thermoelectric figure of merit.

• Proceedings of the Korean DIstribution Association Conference
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• 2006.05a
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• pp.207-226
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• 2006

우리 사회는 정보화와 다원화로 빠르게 변화하고 있다. 경제현상도 변화하고 마케팅의 기법도 다기해지고 있다. 네트워크마케팅(NWM)이란 다단계마케팅(MLM)과 통용되는 개념으로 직접마케팅(Direct Marketing) 기법 중의 하나로 비교적 새로운 유통방법이다. 피라미드와 혼동되어 한 때 비판의 대상이었던 네트워크 마케팅이 실정법에 근거한 새로운 경제활동의 하나로 국민경제에 기능하게 되었다. 올바른 네트워크 마케팅과 실정법에 대한 이해가 필요하며 경제활동의 하나인 이 분야에도 하나님의 주권과 방법이 실현될 필요가 있다. 이 사업에 참여한 성도들은 주님의 피로 사신 교회의 목적에 충실한 행동과 성숙한 신앙인의 자세와 태도로 임할 필요가 있다. 무엇보다도 자신의 재정적 능력범위에서 사업에 참여하는 것이 바람직하다. 일확천금이나 일시에 거금을 번다는 사실과 다른 선전에 현혹되지 말고 자기 자금이나 적정수준의 자본금으로 사업에 참여하는 것이 요구된다. 현행 방문판매법은 교사나 공무원 등의 우월적 지위를 이용하여 상대방에게 다단계 판매를 강요하는 것을 금지하고 있다. 교회에서도 교회 본래의 목적인 복음 전파와 예배 등의 활동과 상치되거나 방해해서는 곤란할 것이다. 자기의 구원과 삶이 바로 서고 이웃을 돌아보아 사랑을 실천하며 복음을 전파하고, 살아서 하나님의 나라를 이 땅에 구현하고 죽어 천국에서 주님과 함께하는 성숙한 신앙생활에 근거해야 할 것이다. 교회도 네트워크마케팅에 대한 바른 이해가 필요하며, 관련 교리에 대한 정확한 이해와 적용이 요구된다고 할 수 있다. 네트워크마케팅에 대한 실정법이 제정되어 있고 현실에 맞게 수차례 개정되어 오고 있으므로 이에 대한 바른 이해가 요청된다. 또한 과학의 발전에 중세의 교회가 이해를 새롭게 한 것처럼, 경제 현상의 변화에 대해서도 통전적인 이해가 요구된다. 이 세상은 근본적으로 하나님이 창조한 세상이기 때문에 이 세상 자체를 악하다고 볼 수 없고 더구나 구원을 이 세상에서의 이탈로 볼 수 없다. 진정한 구원이란 원래 하나님이 보시기에 아름다웠던 그 세상으로의 회복을 포함한다. 이런 면에서 하나님 주권 신앙 하에서 구원이란 전 인격적인 구원, 전 우주적인 구원이 된다. 그렇기 때문에 성도는 세상의 삶과 학문, 예술, 정치, 경제, 사회를 포함한 모든 분야를 하나님의 뜻 가운데서 그 원래의 목적에 부합할 수 있도록 회복시키는 일에 적극 참여해야 한다.