• Journal of the Korean Society of Clothing and Textiles
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• v.40 no.4
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• pp.669-684
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• 2016

This study investigates Korean fighter pilot's usage and satisfaction of a flight duty uniform (FDU). The survey was conducted from October 2014 to March 2015 using Focus Group Interview (FGI) and questionnaires. FGI collected qualitative data about duty and requirements; subsequently, surveys were performed to collect quantitative data about wearing conditions and satisfaction with FDU. The results of the FGI and the questionnaire were as follows. Type of pilot duty was divided into two parts, flight duty and ground duty. It is important to consider duties as well as factors related to survival when developing FDU. According to anthropometric data and wearing size, the basic size for apparel grading should be changed from actual size, 'M95XL' to 'M100L'. It is also necessary to improve the whole sizing system. Further studies about body form changes in pilot's movement are needed to improve mobility because the respondents perceived some restrictions at several body parts in movement with the coverall uniform. Summer FDU had a low satisfaction level in vent hole function and appearance. Furthermore, protection problems in the vent hole were also an issue. Making a seasonal classification of FDU fabric will be more effective than a vent hole to increase a pilot's thermal satisfaction. Respondents had a passive stance towards FDU reform (including pocket change); therefore, a new FDU design strategy should concentrate on improving current FDU functions like mobility (or comfort) rather than dramatic changes. Pilots complained about the quality stability of FDU; therefore, quality control by military administration as well as concrete and clear design instructions by the developer should be attained together. The results obtained in this study are expected to be used as an important basis for the further development of FDU.

• Proceedings of the Korean Geotechical Society Conference
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• 1994.09a
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• pp.199-208
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• 1994

This paper presents an evaluation of new drill and blast method with two different drilling directions for pilot tunnel enlargement using numerical experiment and field test. To evaluate the effieiency of new tunnel enlargement method, field tests were performed and compared with conventional drill and blast method. Also, three dimensional transient dynamic analysis was made to investigate the effect of the ground vibration when blasting was performed at same position using the equivalent single hole charge.

• IE interfaces
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• v.12 no.2
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• pp.337-345
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• 1999

This paper presents the optimization of a drilling operation subject to machining constraints such as power, torque, thrust, speed and feed rate. The optimization is meant to minimize the machining time required to produce a hole. For the first time, the effects of a pilot hole are included in the formulation of the machining constraints. The optimization problem is solved by using the geometric programming technique. The dual problem is simplified based on the characteristics of the problem, and the effects of machining constraints on the machining variables are identified.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2009.05a
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• pp.535-538
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• 2009

Auto Pilot is the system which move automatically the vessel through locating operation mode to automatic after entering operating course using a electronic chart or plotter. And water jet is the a propulsion system that make a power to push the vessel through spouting the accelerated water which is absolbed by the hole in the bottom of vessel. The water jet receive the effect of the depth of water lowly, it's acceletion efficiency is higher under high speed and have an advantage on vibrating and floating sound, so it's demand is increasing as new propulsion system. However, the signal systems of auto Pilot and water jet are defferant, we need the system to communicate between each system. We propose the interface system which communicate between Auto pilot and water jet efficiently in this journal.

• Magazine of korean Tunnelling and Underground Space Association
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• v.4 no.4
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• pp.49-53
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• 2002

향수직굴착용장비로는 승갱굴착기(Raise Boring Machine)과 레이스크라임버(Raise Climber)로 나눌 수 있다. 이장에서는 수직굴착용장비가 다수 있으나 일부장비를 간략하게 소개하며, 추후 공법에 대한 설명할 기회가 주어진다면 좀더 다양한 장비 및 공법에 대해 자세히 기술하도록 하겠다.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.42 no.2
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• pp.197-208
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• 2022

The existence of shallow bedrock and the desire to use underground space necessitate the use of blasting methods. The standard blasting method under water after drilling is associated with certain technical difficulties, including reduced detonation power, the use of a fixed charge per delay, and decoupling. However, there is no blasting method to replace the existing blasting method. In this paper, a dry hole charged with ANFO blasting is assessed while employing a dry hole pumping system to remove water from the drill borehole. Additional standard blasting is also utilized to compare the blasting performances of the two methods. The least-squares linear regression method is adopted to analyze the blasting vibration velocity quantitatively using the measured vibration velocity for each blasting method and the vibration velocity model as a function of the scaled distance. The results show that the dry hole charged with ANFO blasting will lead to greater damping of the blasting vibration, more energy dissipation to crush the surrounding rock, and closer distances for the allowable velocity of the blasting vibration. Also, standard blasting shows much longer influencing distances and a wider range of the blasting pattern. The pilot test confirms the blasting efficiency of dry hole charged with ANFO blasting.

• Proceedings of the Korean Geotechical Society Conference
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• 2005.03a
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• pp.445-456
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• 2005

The research concentrates on improving the in-hole seismic probe, which has been developed in past five years, to be used in stiffness measurements of tunnel-face materials. The probe was down-sized to be fit in 45-mm diameter holes(or BX) drilled by a jumbo-drill, which is used to drill holes to install explosives for tunneling. Also trigger system was improved by using a down-speeding motor for operating convenience and air packing system was replaced with a set of plate-springs to eliminate supply of compressed air. These modifications are to adjust the probe for the unfavourable environment inside of tunnels and to test without any further drilling cost. The probe and testing procedure were successfully adopted with horizontal holes drilled by a jumbo-drill at a tunnel-face to evaluate the stiffness of rock mass. The measured shear wave velocities can be used to estimate deformation properties of rock mass for tunnel analyses.

• The Bulletin of The Korean Astronomical Society
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• v.39 no.2
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• pp.71.1-71.1
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• 2014

The black hole occupation fraction in dwarf galaxies can provide an important clue for understanding the black hole seed formation. As a pilot feasibility study, we performed a KVN radio monitoring campaign over 8 months for 4 dwarf galaxies. Two galaxies (IC10 and NGC1569) are detected at 22 GHz, respectively with 39 mJy, 83 mJy. The measured flux (rms) variability is 13% and 8%, respectively for IC10 and NGC1569, while the mean flux uncertainty is 25% and 12%. Thus, the detection of the radio flux variability is at best marginal. Detecting flux variability of faint sources (i.e., 22 GHz flux < 200 mJy) seems challenging with the KVN single dishes. Combining with the 1.4 GHz flux measurements from the NVSS, we find that these two galaxies have a steep spectrum, supporting that the radio sources are AGNs. Instead of a monitoring, single-epoch multi-band observations can be effective for identifying radio AGNs by providing the constraint of the radio continuum slope.

• Transactions of the Korean Society of Automotive Engineers
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• v.14 no.1
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• pp.138-143
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• 2006

Modification of injector, oil ring tension reduction and oil pump rotor re-matching with optimization of relevant engine control parameters could drive fuel consumption reduction of HSDI diesel engine. A 5 holes injector was replaced with a 6 holes with smaller nozzle hole diameter and 1.5 k factor, and evaluated in a view of fuel economy and emission trade-offs. With introducing smaller nozzle hole diameter injector, PM(Particulate Matter) was drastically decreased for low engine load and low engine rpm. Modification of oil pump and oil ring was to reduce mechanical friction and be proved to better fuel economy. Optimization of engine operating conditions was a great help for the low fuel consumption. Influence of the engine operating parameters· including pilot quantity, pilot interval, air mass and main injection timing on fuel economy, smoke and NOx has been evaluated with 14 points extracted from NEDC(New European Driving Cycle) cycle. The fuel consumption was proved to $7\%$ improvement on an engine bench and $3.7\%$ with a vehicle.

• Journal of the Korean Geotechnical Society
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• v.19 no.3
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• pp.23-31
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• 2003

Over the past half century, borehole seismic surveys have been diversified into the three techniques such as crosshole, downhole, and suspension logging according to their devices and testing configurations. These field techniques have been improved, in terms of equipment and testing procedures, and are very valuable in the evaluation of ground characteristics for geotechnical and earthquake engineering problems. Yet, despite the importance and significance of the techniques as engineering tools, the techniques are not much used as standard penetration test (SPT) by practicing engineers. The possible explanations are cost and operational difficulties of the surveys as well as sophistication and complexity of the devices. An in-hole seismic method has been developed to meet the requirement of economical testing cost and practicality in engineering practice to measure dynamic soil properties. The prototype in-hole probe developed herein is small and light enough to be fit in three-inch boreholes and to be handled with bare hands. The performance of the source has been evaluated through extensive crosshole tests at various sites. The in-hole seismic method was adopted at three test sites and verified by comparing with crosshole results.