• Journal of Korean Tunnelling and Underground Space Association
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• v.18 no.6
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• pp.569-579
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• 2016

In order to ensure the stability of tunnel portal slope, reinforcement method such as anchors, soil nails and rock bolts have been used in Korea. When selecting slope reinforcement methods in tunnel portal area such as reinforcement arrangement and length, trial and error method can be very time-consuming and it was also not easy to verify the selection of an optimum condition. In this study, using the FISH language embedded in the finite difference code FLAC3D program, the optimization technique was developed with the Differential Evolution Algorithm (DEA). After building a database on the soil nailing method in tunnel portal area, this system can be selected to an optimum arrangement plan based on the factor of safety through the FLAC3D analysis. Through the results of numerical analysis, it was confirmed that the number of analysis was decreased by about 8 times when DEA based optimization technique was used compared to the full combination (FC). In case of the design of slope reinforcement in tunnel portal area, if this built-system is used, it is expected that the selection of an optimum arrangement plan can be relatively easier.

• Journal of Korean Tunnelling and Underground Space Association
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• v.20 no.2
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• pp.423-432
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• 2018

Since the Daegu subway fire accident, people's perception of safety has increased, and all materials inside the train have been changed to incombustible materials. However, there is still a lack of development of fire extinguishing systems. Train components are mostly made of steel plates, and therefore it is very difficult to extinguish the train fire by using general fire extinguishing equipment. In this regard, this paper investigated rapid and easy methods of extinguishing the train fire by using compressed air foam systems through full-scale fire tests. To extinguish the fire of train at rescue station, window breakers were used to quickly destroy the train windows, and the compressed air foam system was inserted inside the train. As a result, the train windows were destroyed in 5 seconds, and the 11.88-MW fire was put out in 30 seconds by the compressed air foam discharged from the compressed air foam system inserted inside the train. For the future work, there is a need for further experimental studies to prevent the spread of fire and protect tunnel structures with the use of compressed air foam systems.

• Journal of Korean Society of Environmental Engineers
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• v.33 no.4
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• pp.258-266
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• 2011

Scale induced by hardness materials in water must be controled because of it can be result in remarkable damages of pipeline as well as water quality deterioration. Especially hot water system is one of scale management required facility as scale formation can be accelerated by temperature. The scale control performance of frequency driver (FD) was tested instead of existing methods such as chemical, physical and electromagnetic methods which needs chemicals and electric power. Three kinds of pipe coupons were submerged in test water with 500 mg/L of hardness for 33 days and XRD and SEM were analysed for comparing scale formation characteristics of these coupons. Calcite ($CaCO_3$) which came from hardness of water was formed on only cast iron pipe coupon and this coupon showed higher corrosion rate than copper and stainless steel pipe coupon. Hot water circulating system connected cast iron pipe with and without FD was operated with 300 mg/L of hardness water at $50^{\circ}C$ for monitoring of scale formation and water quality with and without FD. XRD showed that FD leaded to magnetite ($Fe_3O_4$) scale which is good scale for preventing corrosion than calcite and SEM image also indicated the scale control effect of FD. Scales of 16% on pipe joint, 14% on pipe length, and 42% on heat exchanger decreased with FD comparing scales of those parts without FD. From the results of water quality, FD reduced crystallization of hardness material without chemical reaction in water and it can indicate that FD is safe and proenvironmental technology for scale reduction.

• Information and Communications Magazine
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• v.24 no.7
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• pp.26-35
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• 2007

최근 몇 년간 유비쿼터스 서비스를 구현하기 위한 핵심 기술 중 하나인 무선 센서 네트워크에 대한 관심이 높아지고 있다. 무선 센서 네트워크 기술은 물류, 유통, 환경 감시, 홈오토메이션, 군사 분야 등 다양한 분야에 적용 될 수 있기 때문에 앞으로 관련 분야의 시장 또한 커질 것으로 예상되고 있다 [1]. 무선 센서 네트워크는 기존 유선 센서 네트워크나 무선 네트워크 환경과는 많은 차이를 가진다. 우선 극도로 제한된 시스템 자원만을 가질 수 있으며, 열악한 환경 속에서 무선매체를 통해 유기적으로 동작하여야 하는 특징을 가지고 있다. 적게는 수십 개에서 많게는 수백, 수천 개의 자율적인 하드웨어 노드들로 구성되는 무선 센서 네트워크에서 제한된 자원을 효과적으로 활용하기 위해서는 센서 노드에 적합한 운영체제가 필수적으로 요구된다. 지난 몇 년간 센서 노드하드웨어의 발달과 더불어 많은 센서 네트워크용 초소형 운영체제가 개발되어왔다. 현재 많이 알려져 있는 센서 네트워크용 OS로는, 가장 활발한 참여를 보이고 있는 TinyOS[3]부터 SOS[4], MANTIS[5], Contiki[6], T-kernel[7] 등이 있으며, 국내 기술로 개발된 Nano-Qplus[8] 등이 존재한다. 본고에서는 우선 센서 네트워크에 대한 배경 지식과 플랫폼 등에 대한 내용을 간단히 다루고, 본론에서 센서 네트워크용 운영체제가 가져야 할 조건과 현재 개발되어 있는 센서 네트워크 OS들의 특징에 대해 간략히 살펴보도록 하겠다. 또한 센서 네트워크 OS와 밀접한 연관성을 가지는 분야에 대해 간단히 살펴보고, 마지막으로 앞으로의 방향에 대해 알아본다.고려해 볼 때 atlas의 장축의 시계방향 회전은 액티베이터의 사용 효과로 생각되며, 이는 차후 II급 부정교합자에서 액티베이터 치료 효과를 판단하는 또 하나의 지표가 될 수 있다고 생각한다.인해 한반도를 포함한 동아시아 대륙이 태평양판 쪽으로 밀려감으로써 섭입하던 태평양판의 각도가 급해져 동아시아 연변에 강력한 흡입력이 발생하였으며, 이 때문에 태평양판의 운동 방향이 북북서에서 서북서방향으로 회전되었을 가능성이 있다. 따라서 약 51 Ma부터 한반도 동남부에는 지판 경계의 강력한 흡입력으로 동서 내지 서북서-동남동의 인장력이 작동되어 B그룹 암맥군이 관입한 것으로 해석된다.Ledge는 세 군 모두에서 나타나지 않았다. 4. 파일 binding 횟수는 MC군이 가장 적고 PT군이 가장 많았다 (p < 0.05). 이상의 결과를 볼 때, Mtwo 전동 파일을 crown-down technique으로 사용하는 것이 single length technique과 유사한 성형 효율을 보이면서도 더 안전할 것으로 추정된다.고 1명(3%)에서 원격전이를 보였다. 치료 중 급성 합병증으로 11명(37%)에서 RTOG grade 1-2의 장염을 보였으며 1명은 대장의 천공이 발생하여 수술로 치유되었다. 12명(40%)에서 RTOG grade 1-2의 급성 방광염을 보였다. 3명(10%)에서 RTOG grade 1-2의 백혈구 감소증이 보였으며 1명에서 심한 백혈구 감소증(RTOG grade 4)이 나타났으나 회복되어 치료를 완료하였다. 만성 합병증으로 5명(15%)에서 RTOG grade 1-2의 만성 장염을 보였으며 별다른 치료 없이 지내고 있으며

• Journal of Digital Convergence
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• v.16 no.4
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• pp.299-306
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• 2018

This study is to measure traveling experience of bike riders whom going long distance trip. Bike paths and bike riding are crucial element for modern people's life style. At the same time, a bicycle trail is being developed by the National Bicycled-Oriented Chair Plan, which was established in 2009 by the National Bike Policy Master Plan. 13 million bike riders in Korea is keep on trying the long distance bike trip and its number is increasing every year. Accordingly, the Ministry of Public Administration and Security decides to promote the convenience of riders by developing bicycle app for long distance rider. The study attempted to assess usability of this app with 39 bike applications whom currently using the bike application. Afterwards, the researchers tests 11 hypotheses through in-depth interviews of six activated members. In sum, Bicycle travelers should be provided with bike trail guidance based on theme section skill, provided in-time speed distance related information, communicated with other bike riders, given tips for bike supplies and maintenance, and provided English language service. The study hopes to help find a customized service for bike travelers.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.16 no.2
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• pp.116-127
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• 2017

A fog on road is known as a weather factor that affects traffic flow. The method in order to solve the problem, recently, Variable Speed Limit(VSL) which provide reasonable speed limit by road and weather conditions in real time is introduced. However, if drivers do not comply with VSL, the road safety more decrease than without VSL because individual vehicle's speed deviation is larger than without VSL. Therefore, this paper aims to analyze to speed limit compliance and traffic characteristics under foggy conditions with and without VSL. A test using driving simulator divides into normal and foggy condition with visibilities are 200m, 150, 50~100m. The test results showed that 70 subjects's average speed mostly obeyed speed limit, but speed deviation generally declined with VSL. Especially, the speed deviation more reduced under foggy conditions. According to this study, compliance of VSL clearly rose in low visibility and VSL helped improve road safety due to reduction of speed deviation. The results of this study are expected to make use of reasonable speed limit for reference.

• The Journal of the Korea institute of electronic communication sciences
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• v.15 no.3
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• pp.421-432
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• 2020

This paper proposes a 2-kW solid-state power amplifier (SSPA) developed by employing power amplifier pallets designed using gallium-nitride high electron mobility transistors, which is used in S-band military radars and to replace existing traveling-wave tube amplifier (TWTA). The SSPA consists of a high-power amplifier module, which combines eight power amplifier pallets, a drive amplifier module, a digital control module, and a power supply unit. First, the amplifier module and component were integrated into a small package to account for space limitations; next, an on-board harmonic filter was fabricated to reject spurious components; and finally, an auto gain control system was designed for various duty ratios because recent military radar systems are all active phase radars using the pulse operation mode. The developed SSPA exhibited a max gain of 48 dB and an output power ranging between 63-63.6 dBm at a frequency band of 3.1 to 3.5 GHz. The auto gain control function showed that the output power is regulated around 63 dBm despite the fluctuation of the input power from 15-20 dBm. Finally, reliability of the developed system was verified through a temperature environment test for nine hours at high (55 ℃) / low (-40℃) temperature profile in accordance with military standard 810. The developed SSPA show better performance such as light weight, high output, high gain, various safety function, low repair cost and short repair time than existing TWTA.

• Journal of the Institute of Electronics and Information Engineers
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• v.51 no.6
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• pp.132-142
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• 2014

In this paper, we propose a traffic lights detection method using visual attention and spot-lights detection. To detect traffic lights in city streets at day and night time, the proposed method is used the structural form of a traffic lights such as colors, intensity, shape, textures. In general, traffic lights are installed at a position to increase the visibility of the drivers. The proposed method detects the candidate traffic lights regions using the top-down visual saliency model and spot-lights detect models. The visual saliency and spot-lights regions are positions of its difference from the neighboring locations in multiple features and multiple scales. For detecting traffic lights, by not using a color thresholding method, the proposed method can be applied to urban environments of variety changes in illumination and night times.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.36 no.2
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• pp.189-196
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• 2012

The heavy moderator acts as the ultimate heat-sink in an operating CANDU reactor. HUKINS has been developed to investigate moderator flow patterns. HUKINS consists of a 38.4-mm-thick cylindrical shell with a 0.95 m inner diameter and 88 sus-tubes that produce a total heat of 10 kW. A chemical visualization method was selected to estimate the occurrence of typical moderator flow patterns. Momentum-dominated flow, mixed flow, and buoyancy-dominated flow are detected under conditions of a heat load of 7.7 kW and input mass flow rates of 4, 7, and 11 L/min. The experimental results are similar to the results of a CFD simulation that consisted of approximately 1.9 million grids and was conducted using the k-${\varepsilon}$ turbulence model. Therefore, both the present experiments and simulations using HUKINS, a 1/8-scale model, represent all three important flow patterns expected in the real CANDU6 reference reactor. Thus, it has been demonstrated that HUKINS could be useful in the study of CANDU6 moderator circulation.

• Korean Security Journal
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• no.11
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• pp.37-60
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• 2006

The area of security service has been maintaining the high growth curve annually by improving security consciousness from increase of the income and the progress of public services's level by the accomplishment in the info-communication field, recently the demand for unmanned security system is extended form commercial purposes into public offices and individual's houses. In addition to, the possible distance of offering services is scheduled to magnify. At the period when security company's influence has been becoming significant, the injustice transaction is the serious factor which obstructs the development of security companies. Therefore, it is urgent thing to devise counterplans to extirpate injustice transactions. There are the legalistic approaches of the breakthroughs against injustice transactions. One thing is settling the standard of the judgment and the other is renovating the provision of injustice transactions. Utilizing the principles of the fair competitions and importing self-obedience programs within the range of trade actions which is permitted by law, acted as the system approach. Moreover, there are such three things which can achieve mutual balances as establishing the range of the permitted action toward business corporations, applying spontaneously the fair competition principles and introducing the system of standard agreements. Gong further, this can establish order of security service areas and control them. Besides, it is possible for every organizations to make and operate the system appropriately by importing the self-observance system.