• Journal of the Institute of Electronics and Information Engineers
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• v.52 no.4
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• pp.23-29
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• 2015

In this paper, we introduce a underwater ranging algorithm with Look-up Table (LUT) by modifying the existing method which is using the changes of angles of accoustic rays with SSP (Sound Speed Profile). We compare the horizontal distance errors and the calculation times. Our new algorithm exploits Time of Arriva l(ToA) - horizontal distance table based on SSP. This algorithm offers faster calculation speed than the previous one with the slight increase of the distance estimation error.

• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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• 2004.04a
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• pp.119-122
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• 2004

농어촌연구원 내 화강암질편마암지층에 2차에 걸쳐 3공에 대한 공압파쇄 시험 결과 B-1공은 점토성분의 파쇄대 충진으로 수량이 도리어 감소하였다. 공압파쇄 시험 중 파쇄 도달거리를 측정한 결과, P-2 공은 50m 거리에 위치한 B-1공에서의 공압파쇄시험 중에는 약 0.6m의 수위상승이 있었고, 20m 거리에 위치한 B-2공에서의 공압파쇄시험 중에는 약 3.1m의 수위가 상승하였다. 이는 공압파쇄의 유효거리가 암반층에서는 6～15m 정도라고 알려져 있으나 파쇄구간의 발달 정도에 따라 50m 이상 압축공기가 전달됨을 알 수 있다.

• Journal of Advanced Navigation Technology
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• v.23 no.5
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• pp.437-443
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• 2019

In this paper, a new algorithm for the calculation of the range between an LTE base station (BS) and a user equipment (UE) using time-of-arrival (TOA) measurements of LTE signals is proposed. First, the cell identity (cell ID) of the received signal is acquired using the primary synchronization signal (PSS) and secondary synchronization signal (SSS) to identify the BS transmitted the signal. The proposed algorithm exploits the cell-specific reference signal (CRS), the reference sequence inserted in commercial LTE signals, to estimate the time delay using 2D cross-correlation. The obtained TOA estimations can be used to calculate the range employed from the known BS location. The performance of the proposed algorithm is evaluated with the experiment performed using real LTE signals transmitted from the commercial BS.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.14 no.3
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• pp.51-56
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• 2014

TETRA(TErrestrial Trunked RAdio) provide specialized disaster radio communication services as a standard European for digital TRS(Trunked Radio System). Especially, DMO(Direct Mode Operation) feature is used effectively in the radio shadow areas which base station does not propagate radio signal because it can communicate directly with terminal to terminal without base station's relay function. However, to effectively used DMO feature, radio coverage prediction information should be provided to users. Therefore in this paper, we were calculated link budget of TETRA DMO terminals which were distributing and operating in the country and then predicted reaching distance about radio propagation to be applied with path loss model.

• Proceedings of the SAREK Conference
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• 2006.11a
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• pp.64-64
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• 2006

• Proceedings of the Korean Society of Coastal and Ocean Engineers Conference
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• 2003.08a
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• pp.130-133
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• 2003

방파제의 사면 파괴는 파가 구조물에 도달하였을 경우 발생하는 도파가 주된 요인중의 하나로 작용한다. 도파란 파도가 해안구조물에 충돌하여 뛰어 오르거나 기어오르는 현상을 일컫는다. 뛰어오르는 파도의 정상까지의 수직거리를 도파고(h$_{R}$)라 한다. (중략)

• Journal of the Speleological Society of Korea
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• v.12 no.13
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• pp.23-48
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• 1986

영월은 강원도의 서남쪽에 위치하여 우리나라 척량산맥인 태백산맥의 서사면인 영서지방에 점위한다. 태백선과 영동선철도로 연결되는 교통요지로 서울에서 1시간 10분거리에 있다. 영동고속도로로는 새말에서 장평을 거쳐 평창을 지나 영월에 이르게 되나 과거에 근 5시간에 달하던 영월이 수도권에서 3시간남짖으로 도달할 수 있는 교통입지로 앞으로 관광전망이 좋은 위치에 있다. (중략)

• Tunnel and Underground Space
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• v.24 no.3
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• pp.201-211
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• 2014

In the present study, the thermal performance of multiple rock caverns for large-scale thermal energy storage (TES) was numerically investigated for different separation distances between the caverns through heat transfer analysis using a computational fluid dynamics code, FLUENT. The thermal performance of multiple caverns was assessed in terms of the thermal stratification within the caverns and the heat loss to the surroundings, and the heating characteristics of the rock around the caverns were investigated. The results of numerical simulation showed that there was little difference in thermal performance between multiple TES caverns with different separation distances when the surrounding rock was less heated and it reached thermal steady-state, which represent the thermal states of the surrounding rock at the early and long-term operational stages of the TES caverns, respectively. However, as the separation distance decreased, the rock between the caverns reached thermal steady-state more quickly, and thus the heat loss from the caverns tended to converge rapidly to the value of heat loss occurred under thermal steady-state conditions in the surrounding rock. This result implies that the operating cost of heating the surrounding rock (i.e., rock heating) can be reduced with a reduction in the separation distance between multiple caverns, and suggests that the separation distance should be determined by considering the operating cost of rock heating as well as the construction cost of the caverns.

• Journal of Power System Engineering
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• v.11 no.4
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• pp.18-25
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• 2007

제 2세대 직접분사식 가솔린 기관에서 6공 연료분사기의 연료분무특성을 관찰하였다. 실험에 사용한 직접분사식 가솔린 기관은 2개의 흡입밸브와 2개의 배기밸브를 갖는 텀블형 Spray Guided 연소실과 Quartz로 제작된 실린더 라이너와 실린더 헤드 창으로 구성되어 있다. 선회유동을 유도하기 위하여 흡입매니폴드에 선회유동 제어밸브를 부착하였다. 2차원 Mie 스캐터링 기법을 이용하여 연료분사시기, 연료분사압력과 실린더 내 유동 및 냉각수 온도가 연료분무에 미치는 영향을 관찰하였다. 실험결과로는 흡기과정동안 흡기 선회유동은 분사된 연료의 공간적 분포에 크게 작용하였고, 압축과정동안에는 텀블 및 선회유동의 영향이 흡기과정에 비해 크지 않음을 확인하였다. 또한 성층연소를 위해서 압축과정에서 연료를 분사하는 경우 고압의 연료분사압은 분무도달거리의 성장을 촉진시키나 상승하는 피스톤과 이로 인한 실린더 압력의 상승으로 분무도달거리의 성장이 억제됨을 확인할 수 있었다.

• Transactions of the Korean Society of Automotive Engineers
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• v.12 no.6
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• pp.16-22
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• 2004

Dimethyl Ether (DME) has been considered as one of the most attractive alternative fuels for a compression ignition engine. The major advantage of DME-fuelled engine is a great potential for soot-free combustion without sacrificing an inherent high thermal efficiency of diesel engine, despite a necessity for modification of the conventional fuel injection system. An experimental study on DME and conventional diesel sprays was conducted by employing a common-rail type fuel injection system with a 5-holes sac type nozzle, including a constant volume vessel pressurized with nitrogen gas. The injection rates of DME and diesel fuel were recorded with the Bosch type injection rate meter. The injection delay of DME was shorter than that of diesel fuel. The measured injection rates of DME and diesel fuel were correlated with spray penetrations. The prediction method of spray penetration was established using the injection rates, which was verified with the Dent's penetration model and found to agree well for DME case.