• Journal of Radiation Protection and Research
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• v.11 no.2
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• pp.123-129
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• 1986

Using Cs-137 and Co-60 gamma-ray irradiation systems, the buildup factors for 2.9 cm thick lead absorber and the air scattering factors are determined for different beam solid angles from$2.4{\pi}{\times}10^{-3}sr\;to\;17.3{\pi}{\times}10^{-3}sr$. The corresponding buildup factors are turned out to be the values from 1.054 to 1.194 and the scattering factors to be the values from 1 to 1.064, respectively. To verify our results, calculated values using these factors and experimental values are compared. The differences between them are not more than 3. 3%.

• Transactions of Materials Processing
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• v.21 no.6
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• pp.360-365
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• 2012

The aim of this study was to investigate the effects of forming depth on the deformation behavior of cup-like tubes made of AISI1020 steel in tube spinning process. Spinning process was performed on cup-like tubes, which had an inner diameter of 34mm and thicknesses of 7, 8.5 or 11.5mm. The forming depths achieved were 3, 4, and 5.5mm. The complex deformation behaviors occurring during the tube spinning process was explained using the experimental results. Also analyzed were the causes of the material buildup and the bulge defect of inner surface, observed on cross section of tubes. The relationship between tube spinning conditions and the height of bulge defect was examined. The results indicate that bulge defect is increased with a decrease of the forming depth. Moreover, a critical forming depth exists for preventing the generation of the bulge defect in the tube spinning process. The present results will be useful for future decisions of forming depths for successful tube spinning of cup-like tubes.

• Laser Solutions
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• v.14 no.1
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• pp.14-18
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• 2011

Semiconductor industry demands decrease in line/space dimensions of IC substrates. Particularly for IC substrates for CPU, line/space dimensions below $10{\mu}m/10{\mu}m$ are expected to be used in production since 2014. Conventional production technologies (SAP, etc.) based on photolithography are widely agreed to be reaching capability limits. To address this limitation, the embedded circuit fabrication technology using laser ablation has been recently developed. In this paper, we used a nanosecond UV laser and a picosecond UV laser to fabricate embedded circuit patterns into a buildup film with $SiO_2$ powders for IC substrate. We conducted SEM and EDS analysis to investigate surface quality of the embedded circuit patterns. Experimental results showed that due to higher recoil pressure, picosecond UV laser ablation of the buildup film generated a better surface roughness.

• Journal of the korean Society of Automotive Engineers
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• v.10 no.6
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• pp.48-53
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• 1988

In a previous report, the properties of vegetable oils as diesel fuel substitutes were investigated and the basic load performance of a diesel engine was examined using vegetable oil. The results show that despite of the long term chain hydrocarbon structure and large droplet size due to high viscosity, vegetable oils have good basic performance and exhaust emissions, however they cause serious problems as carbon deposit buildup, they have poor durability, and also poor thermal efficiency. In this paper, the startability and engine durability with long term operation was tested by physical methods for reducing viscosity when vegetable oil was used as compared against diesel fuel. The results obtained in this investigation may be stated as follows; (1) There is no problem in startability when vegetable oil was used as diesel fuel substitutes as far as fuel temperature is higher than 30.deg. C (2) The carbon deposits were most extensive at lower loads and lower engine speeds, and deposit buildup more heavily on the cooler parts of the combustion chamber wall. (3) Blends with 25% diesel fuel and 20v-% ethanol are effective in reducing the carbon deposit buildups. (4) Significant improvement in carbon deposit and piston ring stick can be obtained by heating fuel(200.deg.).

• Journal of Radiation Protection and Research
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• v.43 no.1
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• pp.20-28
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• 2018

Background: Heat energy produced in nuclear reactors and nuclear fuel cycle facilities interactions modifies the physical properties of the shielding materials containing water content. Therefore, in the present paper, effect of the heat on shielding effectiveness of the concretes is investigated for gamma and neutron. The mass attenuation coefficients, effective atomic numbers, fast neutron removal cross-section and exposure buildup factors. Materials and Methods: The mass attenuation coefficients, effective atomic numbers, fast neutron removal cross-section and exposure buildup factors of ordinary and heavy concretes were investigated using NIST data of XCOM program and Geometric Progression method. Results and Discussion: The improvement in shielding effectiveness for photon and reduction in fast neutron for ordinary concrete was observed. The change in the neutron shielding effectiveness was insignificant. Conclusion: The present investigation on interaction of gamma and neutron radiation would be very useful for assessment of shielding efficiency of the concrete used in high temperature applications such as reactors.

• The Transactions of the Korean Institute of Electrical Engineers C
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• v.48 no.5
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• pp.385-390
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• 1999

Surface corona discharge characteristics of a dc corona charged ferroelectric pellet barrier have been investigated experimentally. Electric charges stored on the surfaces of the ferroelectric pellets by a dc corona discharge provide partial electric fields on the surfaces of the ferroelectric pellets, which could generate surface corona discharges on the ferroelectric pellets. This system utilizes both the surface discharges on the ferroelectric pellet barrier and the corona discharge between corona tip and mesh electrode. Positive and negative dc voltages were applied to the tip to generate partial discharges, and corona currents were estimated to investigate the buildup charge on ferroelectric pellets as a function of the applied time and the charge relaxation time constants of ferroelectric pellets. As a result, in the case of the negative corona discharge with the ferroelectric pellet barrier, the mean corona current and ozone generation increase greatly, and the surface discharges on the ferroelectric pellets can be fenerated efficiently. It is also found that, charge relaxation time, dielectric constants offerroelectric pellets, polarity of applied voltage and applied time affected to the surface discharges among the ferroelectric pellets.

• Strategy21
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• s.40
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• pp.5-36
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• 2016

Recently, the Japanese government revised the three guidelines of its security policy, the National Security Strategy(NSS), the National Defense Program Outline and Midterm Defense Buildup Plan, exceptionally at one time. This means Japan has been seeking the new strategy and strengthening military power considering changing regional security environment. Moreover, Japan revised the security laws for the right to collective self-defense, which authorized the use of force even when Japan is not under attack. Also, Japan renewed the Guidelines for Japan-U.S. Defense Cooperation in twenty years, and has expanded JSDF's scope of activity to a worldwide level. These changes imply Japan would constantly seek to build military forces focusing on naval forces. Because Japan's naval forces, the JMSDF is the means that allow Japan to use its force at anywhere overseas and expand its roles and missions in international society by the basis of the right to collective self-defense. This research will analyze Japan's new maritime strategy and trend of force development and eventually look for the implication on our maritime security These days, Japan has perceived Chinese rapid increase of naval power and pursuing of maritime hegemony as a grave threat. In response to this, Japan is designing new maritime strategy, which are "remote islands defense and recapture" and proactively develop a new type of naval forces to accomplish this new strategy. The Japan's "remote island defense and recapture strategy" is to harden its defensive posture in Nansei islands which correspond to China's 1st island chain for chinese A2/AD strategy and directly encounter with China and to protect its own dominium and maritime interest while supporting US national strategy in East Asia. Japan continues to build compact, multi-functional ship to accomplish "remote island defense and recapture strategy" and keep strengthening its maritime power projection capability to include build of new amphibious ship, and large, multi-functional ship which can provide effective C2. These changes imply that Japan is shifting its strategy from passive and defensive to proactive and aggressive way and continues to pursue naval buildup.The implication of Japan's new maritime strategy and naval buildup needs to be observed carefully and we need to keep developing naval power required to protect our maritime sovereignty and interest.

• 방재와보험
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• s.122
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• pp.36-44
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• 2007

BP 텍사스 시티의 석유정제소의 화재폭발은 2005년에 가장 많은 인명의 손실을 끼친 유동화자산의 화재폭발사고로서 15인의 생명을 앗아가고 200여 명의 사람을 다치게 하였다. 트럭 한 대의 역화(내연기관의 부정폭발)에서 시작된 점화원은 이성질체화시스템(ISOM) 대기암 통기구에서의 가연성 탄화수소 액체와 증발 기체를 발화시켰다. 화학안전위원회는 그 사고를 조사 및 검토한 후 BP사가 모든 면에서 기계적인 결함과 함께 안전성이 불완전하였음을 발견하였다. 본 고는 저자들이 미국화학안전위험조사위원회에 제출한 이들의 조사보고서를 번역 게재한 것이다.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2012.05a
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• pp.171-172
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• 2012

• Proceedings of the Korean Society of Agricultural Engineers Conference
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• 1998.10a
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• pp.204-209
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• 1998

The creation of favorable water space, in our living circumferential space, is a very important factor to offer rural scenery to neighbor residents. In other to arrange stream landscape, we developed Stream Landscape Simulation System(SLSS). SLSS is combined with image and database rotationally. SLSP system creates composed simulation image overlaying both background and landscape image. This system is to compare and estimate original landscape image with simulated one. SLSP system needs continuing development and buildup of Unified Relational Image Database(mm) to design of various landscape.