• Journal of Biosystems Engineering
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• 제34권6호
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• pp.404-410
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• 2009

This study was carried out to develop a self-propelled type explosive subsoiler for improving the root zone soil conditions in orchard and other forest fields. Prototype was designed to be able to inject air and other soil improving material such as lime into soil at the same time, and thus improve the air permeability and drainage of orchard soils to promote the root growth of tree for high quality fruit production. Soil penetration device of explosive subsoiler is composed of air hammer, penetration rob and air injection nozzle. To support the soil penetration device of explosive subsoiler to penetrate vertically, modified Scott-Russel mechanism was used. Timing control device for simultaneous injection of soil improving material with air was attached to the out side wall of air cylinder and as the cylinder move, the soil improving material was injected into soil at the same time. Turning radius of prototype was 2.2-2.3 m with good mobility in sloped land. It took approximately 1 minute for lime injection system to reach the optimum pressure of 9.9 kg/$cm^2$, average 10-20 seconds were required to rupture soil with the depth of 50 cm and 2-3 seconds were required for explosion, so all in all about 1 minute and 20 seconds were required for one cycle of explosion. Maximum soil rupture depth and diameter were 50 cm and 3-4 m respectively depending on the soil type and soil moisture content. For final design of explosive subsoiler inclination angle of lime hopper was increased from 60 degree to 70 degree and the shape of hopper was changed from rectangular cone to circular cone to solve the clogging problem of lime at out let. Agitating system operated by compressed air was attached to the metering device of the prototype, thus more than 90 cc of lime was discharged per cycle from metering device without clogging problems.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2007년도 추계학술대회 논문집
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• pp.974-981
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• 2007

Seoul Metro has operated the air cooling equipment established in a machine room of a station building to improve our services focused on our customers who use Seoul Metro during the summer season. However, a new set of problems has arisen with the cooling tower to support a heat exchange of cooling water. One of them is loss of efficiency in the air conditioner. The leading cause of this problem is that we use an underground type of the cooling tower. As the machine room of a station building is located in the underground of inner city because of the nature of the subway, it is difficult to establish the cooling tower on the ground. The underground structure of the No. $1{\sim}4$ subway line is unsuitable for the location requirements of the underground type of the one because it has a limited space to set up the air cooling equipment, for example, the cooling tower and a ventilating opening. As a result of such an unfavorable condition, the cooling tower doesn't work efficiently and the warmth of cooling water because of insufficiency of a heat exchange and a refrigerator's technical obstacle such as a high-temperature and a high-pressure has arisen. Accordingly, the efficiency of the air conditioning is getting lower and lower. Another problem is too wasteful with water. Each station uses the water over 30 tons every day with waterworks to replenish the cooling tower such as a evaporation, a scattering and a distribution of water. Nevertheless, the more an air conditioner increase, the more the use of water supply increase. For this reason, we can't help wasting an enormous amount of water and discharging the congelation of a low temperature(about $15^{\circ}C$) occurred in a heat exchanger inside an air conditioner. The purpose of this study is to analyze the utility of congealing water to improve efficiency of the air cooling equipment and save energy as a supplementary water for the cooling tower.

• 한국항행학회논문지
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• 제22권5호
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• pp.367-374
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• 2018

차세대 통신링크를 활용한 항공로 교통 관리를 위해 궤적 기반의 관제 지원 스케줄링 시스템을 제안하였다. 차세대 ATS (air traffic services) 데이터링크인 Baseline 2를 사용하는 4DTRAD (4-dimensional trajectory data link) 서비스 내용을 기반으로 항공로 상을 비행 중인 항공기를 대상으로 하는 궤적기반운용 수행 절차를 수립하고 기술하였다. 이러한 절차를 바탕으로, 다양하고 복잡한 데이터 활용으로 인한 관제사의 업무 부담을 완화하기 위해 지상 시스템이 수신한 항공기 데이터를 처리하여 궤적을 예측하고 관제 조언 정보를 제공하는 스케줄링 시스템의 프로토타입을 개발하였다. 또한, 궤적 기반 항행을 위한 시뮬레이션 환경을 구성하여 개발 시스템에 대한 스케줄링 기능을 확인하였다.

• 반도체디스플레이기술학회지
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• 제10권1호
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• pp.33-41
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• 2011

Due to the recent quantum leaps forward in bio-, nano-, and information-technologies (BT, NT and IT), the precisionization and miniaturization of mechanical and electrical components are in high demand. In particular, the ITrelated equipments that take a great part in our domestic industry are in the area requiring high precision technologies. As a consequence, the researches on the development vibration isolation systems that diminish external disturbance or internal vibration are highly required. Among the components comprising the vibration isolation system, air spring has become on a focal point for the researchers due to its merits. This air spring is able to support heavy loads, keep a low natural frequency despite of having a lower value of stiffness, and control the performance of vibration isolation. However, sometimes the sole use of air spring is in demand due to some economic reasons. Under this circumstance, the damping effect of sole air spring may not enough to reduce sufficient amount of vibration. In this study, the air spring mount system connecting with an external chamber is proposed to increase or control the damping effect. To investigate its damping mechanism, the thermal and dynamic behaviors of the system is examined through a theoretical modeling approach in this part of research. In this approach, thermomechanical and Helmholtz resonator type models are to be employed for the air spring/external chambers and connecting tube system, respectively. The frequency response functions (FRFs) derived from the modeling effort are evaluated with physical parametric values and the effects of connecting tube length on these FRFs are identified through computer simulations.

• 한국대기환경학회지
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• 제27권4호
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• pp.460-471
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• 2011

A port has been regarded as a significant contributor to air pollution in the surrounding areas. Port-related air pollutants are released from not only marine vessels, but also various land-side sources at ports, which include cargo handling equipment, vehicles, locomotives, and fugitive dust sources by port activities such as bulk handling and vehicle movements. However, most studies in Korea have only focused on vessel emissions and there is a lack of information on the emissions from other sources at port. In this study, in order to establish the port-related emission inventory and evaluate the relative contribution of these sources to air emissions from the Port of Incheon, the emissions from land-side sources were estimated and the CAPSS (Clean Air Policy Support System) data for vessel emissions were used. In particular, the detailed information and activity data for the cargo handling equipment source were collected and the emission factors and emissions by equipment types were calculated using U.S. EPA methodologies. Total HC, CO, $NO_x$, $PM_{10}$, and $SO_2$ emissions from port-related sources including the vessel in 2007 were calculated as 229 ton/year, 638 ton/year, 4,861 ton/year, 307 ton/year, and 3,995 ton/year, respectively. It was found that the vessel was the largest contributor to air pollutant emissions from the port, the cargo handling equipment was responsible for about from 8% to 13% of HC, CO, and $NO_x$ emissions and the resuspended road dust contributed about 39% for $PM_{10}$ emissions. The results of this study will be used to establish the management and reduction strategies of air pollution in the port.

• International journal of advanced smart convergence
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• 제12권1호
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• pp.173-183
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• 2023

Recently, local governments that provide mobile-based public delivery app services have been increasing a lot. The purpose of this study is to analyze whether the restaurant self-employed's public delivery app selection attributes and public institutions' perception of support, which are under economic pressure due to the high delivery fee burden of private delivery apps, affect the intention to use public delivery app services. In this study, the degree of perception of each factor was measured using the Likert 5-point scale, and it was verified through statistical analysis using SPSS. The effect of the selection attribute of public delivery apps and the perception of self-employed people in the restaurant industry on the intention to use the service was empirically analyzed, and the hypothesis was verified using regression analysis. As a result of this study, it was confirmed that convenience, economy, and public interest had a significant effect among the factors of public app selection attributes, and educational support had a significant effect on public institution support.

• 콘크리트학회논문집
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• 제25권3호
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• pp.339-345
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• 2013

이 연구는 200000 $m^3$의 용량을 갖는 지하식 LNG 저장탱크의 지붕 콘크리트에 대한 요구성능 및 이에 따른 콘크리트의 최적배합비를 도출하고, 현장시공의 자료로 제안하기 위한 것이다. 지붕 콘크리트는 돔형 지붕의 경사기울기에 따라 굳지 않은 콘크리트의 시공성 및 충전성이 요구된다. 또한, 1.4~0.6 m의 지붕두께를 고려한 수화열 저감과 콘크리트 타설 후의 프리스트레싱 작업 및 air support의 제거공정에 따른 단계별 압축강도의 확보가 중요한 요구성능이다. 이러한 조건을 고려하여 지붕의 기울기가 $20^{\circ}$ 미만일 경우에는 슬럼프 $100{\pm}25$ mm, $20^{\circ}$ 이상일 경우에는 $150{\pm}25$ mm로 선정하였으며, 경시변화 60분을 만족해야 한다. 특히, 91일 재령의 설계기준강도 30 MPa, 프리스트레싱 작업시 7일 재령의 압축강도 10 MPa, air support 제거공정에서 21일 재령의 압축강도 14 MPa을 만족해야 한다. 석회석 미분말의 최적 치환율은 구속시험 결과에 따라 정하였으며, 주요 배합변수는 물-시멘트비, 잔골재율 및 고성능 AE감수제의 첨가율 등이다. 배합시험 결과, 저열 포틀랜드 시멘트 및 석회석 미분말을 사용한 지붕 콘크리트의 최적배합 조건은 석회석 미분말의 최적 치환율 25%(내할), 물-시멘트비 57.8%, 잔골재율 42.0%로 나타났으며, 공기량 및 슬럼프의 시험결과도 경시변화 60분까지 성능을 만족하였다. 또한, 단열온도 상승시험의 결과, 단열온도 상승양($Q{\infty}$)이 $26.3^{\circ}C$, 상승속도(${\gamma}$) 0.58로 선행탱크(TK-13,14)와 비교해 볼 때 매우 낮게 나타나 수화열 저감의 효과를 기대할 수 있다. 이러한 요구성능 및 최적배합 조건을 만족하는 설계기준강도 30 MPa(배합강도 36 MPa)의 지하식 LNG 저장탱크의 지붕 콘크리트용으로 제안하였다.

• 한국통신학회논문지
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• 제39C권11호
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• pp.1050-1067
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• 2014

CAS는 근접항공지원 작전으로 아군과 근접해 있는 상황에서 적을 항공기로 공격하는 작전이다. CAS의 여러형태 중에 긴급 CAS는 CAS 임무 형태 중에 사전 계획 없이 요청한 표적에 대하여 공격하는 임무로, 적절한 항공기를 분배하는 것이 임무 결과에 커다란 영향을 미친다. 하지만 긴급 CAS 분배에 관련한 이전 연구에서는 항공기의 적합도를 고려한 경우를 찾기 힘들었다. 2014본 연구는 항공기 적합도를 고려한 긴급 CAS 자원 분배 방법론을 제시하고자 한다. 방법론은 총 3단계로 이루어져 있으며 1단계에서, 표적 정보를 바탕으로 상황분석을 실시하고, 2단계에서는, 상황분석 결과를 이용하여 각 표적별로 타격 자산들을 적합도를 정량적으로 산출하며, 3단계에서는 산출한 적합도를 바탕으로 산정한 CAS 분배 추천 안을 결정권자에게 제시한다. 이 방법론은 긴급 CAS 자산 분배에 관한 정량적인 분석을 제공함과 동시에, 추천 대안을 제시함으로써 의사결정을 보다 신속하고 효율적으로 할 수 있도록 지원한다.

• 한국정밀공학회지
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• 제25권8호
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• pp.104-110
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• 2008

The aim of this study ultimately is verifying that PGO gait is more efficient than RGO fur paraplegics because the air muscle assists hip flexion power in heel off movement. The gait characteristics of the paraplegic wearing the PGO or RGO are compared with that of a normal person. PGO with air muscles was used to analyze the walking of patients with lower-limb paralysis, and the results showed that the hip joint flexion and pelvic tilt angle decreased in PGO. In comparison to RGO gait, which is propelled by the movements of the back, PGO uses air muscles, which decreases the movement in the upper limb from a stance phase rate of 79$\pm$4%(RGO) to 68$\pm$8%. The energy consumption rate was 8.65$\pm$3.3 (ml/min/Kg) for RGO, while it decreased to 7.21t2.5(ml/min/Kg) for PGO. The results from this study show that PGO decreases energy consumption while providing support for patients with lower-limb paralysis, and it is helpful in walking for extended times.

• 항공우주산업기술동향
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• 제8권2호
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• pp.113-123
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• 2010

국제민간항공기구 ( ICAO )는 증가하는 항공교통량을 수용하고 안전성과 효율성을 증대시키기 위하여 위성항법과 데이터 통신 기술이 접목된 차세대항행시스템의 개발과 구축을 권고하였다. 차세대 항행시스템 은 항공통신, 항공항법, 항공감시 및 항공교통관리로 구성되어 있다. ICAO는 차세대 항행시스템을 위한 국제 항행 계획을 수립하였고, 세계 항공선진국은 이 계획을 충족하고 항공교통 인프라의 전환을 위하여 CNS/ATM 연구개발을 추진하고 있다. 본 논문에서는 국내기술개발의 방향과 방안 수립을 위하여 차세대 항행시스템의 국내 외 기술동향을 분석하였다.