• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.39 no.4
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• pp.378-384
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• 2011

During the flight test of KSLV-I, various sensors are installed in the launch pad and the flame deflector to measure the flame characteristics and their influences on the launch complex when a launch vehicle lifts off. Parameter Measurement System is responsible for acquiring the above flight test data. The measurement methodology such as the configuration of measurement system, sensor locations and data acquisition procedures are presented. And this paper compares and explains the characteristics of data sets measured during two flight tests.

• Korean Journal of Materials Research
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• v.17 no.8
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• pp.402-407
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• 2007

In electronics manufacturing processes, soldering process has generally been used in surface mounting technology. Because of environmental restriction, lead free solders as like a SnAgCu ternary system are being used widely. After soldering process, the formation and growth of intermetalic compounds(IMCs) are formed in the interface between solder and Cu substrate as follows isothermal temperature and time. In this studies, therefore, we investigated the effects of the Cu substrate thickness on the IMC formation and growth of Sn-40Pb/Cu and Sn-3.0Ag-0.5Cu/Cu solder joints, respectively. The effect of the Cu thickness in PCB Cu pad and pure Cu plate was analyzed as measuring of thickness of each IMC. After solder was soldered on PCB and Cu plate which have different Cu thickness, we measured the IMC thickness in solder joints respectively. Also we compared with the effectiveness of Cu thickness on the IMC growth. From these results, we calculated the activation energy.

• Proceedings of the KSR Conference
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• 2008.06a
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• pp.941-947
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• 2008

In the braking of a railroad car, mechanical brake systems using wheel tread and brake disk are applied as well as electrical brake systems by regenerator and rheostat. During disk braking, kinetic energy of the vehicle is converted into thermal energy through friction between disk and brake pad. And it causes high temperature concentration and generates thermal crack on the brake disk surface. In this study, comparative test process for heat-resistance of candidate materials was designed for development of brake disk materials having high heat-resistance. We also verified the efficiency of the process by experiments using conventional brake disk materials.

• Journal of the Microelectronics and Packaging Society
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• v.14 no.1
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• pp.1-9
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• 2007

OSP(organic solderability preservatives) finish has been considered as a very effective process for substituting the metal surface treatment of Ni/Au finish because of lower cost, interface property and environmental issue of OSP finish. However, the discoloration of OSP layer is formed during assembly process consisting of various steps of temperature. The causes of discoloration and the characterization of solder joint were investigated with a degree of discoloration and the assembly process of OSP finished products, which was also compared statistically with that of conventional Ni/Au finished products. As the results, the solution of process trouble for OSP finished products is able to be offered.

• ETRI Journal
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• v.35 no.4
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• pp.625-631
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• 2013

For the formation of solder bumps with a fine pitch of 130 ${\mu}m$ on a printed circuit board substrate, low-volume solder on pad (LVSoP) technology using a maskless method is developed for SAC305 solder with a high melting temperature of $220^{\circ}C$. The solder bump maker (SBM) paste and its process are quantitatively optimized to obtain a uniform solder bump height, which is almost equal to the height of the solder resist. For an understanding of chemorheological phenomena of SBM paste, differential scanning calorimetry, viscosity measurement, and physical flowing of SBM paste are precisely characterized and observed during LVSoP processing. The average height of the solder bumps and their maximum and minimum values are 14.7 ${\mu}m$, 18.3 ${\mu}m$, and 12.0 ${\mu}m$, respectively. It is expected that maskless LVSoP technology can be effectively used for a fine-pitch interconnection of a Cu pillar in the semiconductor packaging field.

• Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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• 2001.06a
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• pp.271-280
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• 2001

An NAO friction material (low-steel type) containing 15 ingredients was investigated to study the role of transfer film on the friction characteristics. The friction material specimens with extra 100% of each ingredient were tested using a pad-on-disk type tribotester. A non-destructive method of measuring the transfer film was developed by considering the electric resistance of the transfer film. Results showed that solid lubricants and iron powder assisted transfer film formation on the rotor surface. Average friction coefficient was independent of transfer film thickness in this experiment. On the other hand, the thick transfer film on the rotor surface reduced the amplitude of friction oscillation under temperature conditions ( 250$^{\circ}C$) that transfer film forms.

• Journal of the Korean Society for Precision Engineering
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• v.23 no.8 s.185
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• pp.178-184
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• 2006

Hot embossing is to fabricate desired pattern on the polymer substrate by pressing the patterned mold against the substrate which is heated above the glass transition temperature, and it is a high throughput fabrication method for bio chip, optical microstructure, etc. due to the simultaneous large area patterning. However, the bad pattern fidelity in large area patterning is one of the obstacles to applying the hot embossing technology for mass production. In the present study, PDMS pad was used as a cushion on the backside of the micro-patterned 4 inch Si mold to improve the pattern fidelity over the 4 inch PMMA sheet by increasing the conformal contact between the Si mold and the PMMA sheet. The pattern replicability improvement over 4 inch wafer scale was evaluated by comparing the replicated pattern height and depth for PDMS-cushioned Si mold against the rigid Si mold without PDMS cushion.

• Journal of Practical Agriculture & Fisheries Research
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• v.11 no.1
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• pp.183-195
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• 2009

시설하우스의 공기환경은 작물생육에 큰 영향을 준다. 특히 기공주변 공기의 상대습도는 증산작용에 크게 영향을 주며, 안개가 끼게 되면 기공을 통한 증산작용이 일어나지 않아 작물은 생육을 멈추게 된다. 이에 대한 이론적 고찰을 습공기선도를 중심으로 살펴보았으며, 그 기술을 권왕림(경기도 이천시 백사면 모전2리 192) 쌈채소 재배 농장과 정기설(경기도 용인시 백암면 석천리) 백암육계 농장에 적용한 결과를 요약하면 다음과 같다. 1. 여름철 온실 공기의 온도를 낮추기 위하여 널리 사용하는 Pad & Fan, Mist & Fan 등의 증발냉각 방법은 사막 기후지역(온도는 높고 습도는 낮은 지역)에 적합한 방법으로 우리나라와 같이 고온 다습한 기후에는 적합하지 않다. 2. 겨울철 저녁에 온실을 보온하기 전에 따뜻한 공기의 열이 연료비를 절감 할 수 있다는 생각으로 환기를 하지 않으면 절대습도가 높아 약간의 온도가 떨어져도 안개가 발생하게 된다. 3. 겨울철 저녁에 온실을 보온하기 전에 외부 공기로 충분히 환기하여 절대습도를 낮추면 노점온도가 낮아지고, 약간의 난방으로도 온실의 안개를 방지할 수 있다. 4. 여름철 상추재배에서 시원한 바람으로 공기환경을 개선한 결과 41.6%의 증수효과가 있었다. 5. 겨울철 육계농장의 공기환경 개선으로 47,300수 기준으로 폐사율 2%와 난방연료 40%를 절감할 수 있었으며, 육계 성장의 균일도를 53%→73%로 20%정도 높일 수 있었다. ※ 정기설 백암육계 농장(경기도 용인시 백암면 석천리) (011-719-7597)

• Journal of the Microelectronics and Packaging Society
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• v.17 no.4
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• pp.35-40
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• 2010

In this study, the reliability of thermal shock, thermal cycle, and complex vibration test at high temperature were examined for 3 types of lead-free solder alloys, Sn-3.5Ag, Sn-0.7Cu and Sn-5.0Sb. For the reliability test, daisychained BGA chips with ENIG-finished Cu pad was assembled with the three lead-free solders on OSP-finished PCBs. Among the 3 types solder alloys, Sn-3.5Ag solder alloy showed the highest degradation rate of electrical resistance and joint strength. On the other hand, Sn-0.7Cu solder alloy had high stability after the reliability tests.

• Journal of Animal Science and Technology
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• v.57 no.3
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• pp.9.1-9.5
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• 2015

Background: A simple binary scoring system (SBSS) was developed and used to assess the welfare measures of commercial broiler chickens in South Korea. We also correlated welfare measures with environmental parameters of broiler house. Our measures of welfare included lameness, hock burn (HB) and foot pad dermatitis (FPD), whilst environmental parameters included air temperature, relative humidity, air speed, light intensity, air quality (in particular carbon dioxide ($CO_2$) and ammonia ($NH_3$) concentrations) and airborne microbes. Results: The effect of environmental parameters on welfare measures was apparent even on 10-day-old broilers. A non-parametric correlation analysis revealed significant correlations between environmental parameters and welfare measures. The key environmental parameters were relative humidity and light intensity. The results indicate that there is a need for proper control of environmental conditions on poultry farms, which could reduce health problems and subsequently reduce disease and mortality. Conclusions: In conclusion, the simplicity of SBSS makes it preferable over more complex scoring systems and allows a farmer to more easily assess the welfare measures on their own farm.