• Journal of Forest and Environmental Science
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• 제30권1호
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• pp.56-61
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• 2014

Macroscopic and microscopic characteristics of Yellow-hearted pine and Red pine were investigated. Wood color, annual ring width and latewood percentage were observed by the naked eye. Anatomical properties as the structure of three sections and cell dimensions were examined by an optical microscopy. As a result, the color of bark in Yellow-hearted pine was Reddish-grey, and Red pine showed brown or gray. The color of heartwood and sapwood in Yellow-hearted pine was deep-yellow to brown and creamy-white. And the color of heartwood and sapwood in Red pine was light-brown and light-yellow. The annual ring width of Yellow-hearted pine was narrower than that of Red pine, and the latewood percentage of Yellow-hearted pine was a little higher than that of Red pine. There was no significant difference in the anatomical characteristics between Yellow-hearted pine and Red pine.

• 한국자동차공학회논문집
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• 제8권5호
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• pp.20-27
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• 2000

Characteristics of two favorite injection tools for gasoline direct injection application were compared. An air-assisted fuel injector (AAFI) and a high-pressure swirl injector (HPSI) were designed and fabricated for prototype development, and the characterization strategies and processes for both injection tool have been arranged in parallel. Characterization works were carried out mainly through measurements, and in some cases, computational fluid dynamic analysis was utilized. In this paper, overall characteristics defined as flow rate, spray pattern, penetration, internal spray structure and drop size distribution, was discussed. The AAFI was found to be advantageous in flexibility of fuel flow rate, and the HPSI in stability and precision. Spray shape factor was introduced to describe the development of intermittent sprays from both injectors. Axial penetration appeared to be almost linear in the case of the AAFI while its speed continuously decreased with time in the HPSI.

• 한국ITS학회 논문지
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• 제11권6호
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• pp.15-22
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• 2012

신호교차로의 효과척도는 신호교차로의 신호시간을 최적화 하고 단속류의 교통류를 관리하는데 기준이 되는 척도이다. 일반적으로 교차로나 네트워크를 주행하는 차량의 평균 지체시간을 줄이기 위하여 지체시간을 효과척도로 사용하고, 일부 교통축을 개선하거나 버스의 우선 통행을 위하여 연동효율을 효과척도로 사용하기도 한다. 교통류를 관리하고자 하는 현장 상황이나 목적에 따라 두 개의 효과척도 중 하나를 선택하여 각 척도의 목적에 맞게 신호시간을 관리하고 운영하고 있다. 그러나 실제 운전자가 도로를 주행할 때는 척도와 상관없이 대기시간이 짧을 수록, 교차로에서의 불필요한 정지가 적을수록 운전자의 만족도는 커진다. 본 연구는 지체시간과 연동성 구분없이 두 개를 동시에 고려하여 반영할 수 있는 시뮬레이션 모형을 개발하고자 한다. 기존의 연동폭 최대화 모형에서 반영하지 못한 교통량 수준과 정지선에 미리 대기하고 있던 잔여차량의 영향을 고려하기 위하여 밀도-교통량 곡선을 이용한 충격파 모형을 적용하였다. Daganzo의 Cell Transmission Model을 차용하여 지체시간과 연동지표를 개발하고 시뮬레이션 모형을 구축하였다. 본 모형의 효과를 검증하기 위하여 기존 지체시간 모형인 Transyt-7F와 연동폭 최대화 모형은 PASSERⅤ를 기준으로 지체시간과 연동효율을 산출하여 비교분석하였다.

• Asian Pacific Journal of Cancer Prevention
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• 제13권6호
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• pp.2515-2518
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• 2012

Aim: To study the causes and significance of both microscopic and macroscopic haematuria in adult patients and assess possible relevance to early detection of urological cancers. Methods: 417 patients presenting with haematuria were assessed in our Urology Unit. Following confirmation of haematuria, these patients were subjected to imaging techniques and flexible cystoscopy. Parameters analysed included clinical characteristics, imaging results, flexible cystoscopy findings, time delay to diagnoses and eventual treatment and final diagnoses of all cases. Results: 390 haematuria cases were analysed from 417 consecutive patients with haematuria. After 27 cases were excluded as they had previous history, 245 microscopic and 145 macroscopic. Age range was 17 to 95 years old with predominance of 152 females to 239 males. The racial distribution included 180 Chinese, 100 Indians,95 Malays and 15 other races. The final diagnoses were benign prostatic hyperplasia (22.6%), no cause found (22.3%), other causes (18.7%), urolithiasis (11.5%), urinary tract infection UTI (10.8%), non specific cystitis (10.3%), bladder tumours (2.8%) and other genitourinary tumours (1%). 11 new cases (2.8%) of bladder cancers were diagnosed, with a mean age of 59 years. Only 3 of 245 (1.2%) patients with microscopic haematuria had newly diagnosed bladder tumour compared with 8 of 145 (5.5%) patients with frank haematuria (p=0.016). Mean time taken from onset of symptoms to diagnosis of bladder cancer was 53.3 days with definitive treatment (TURBT) in 20.1 days from diagnosis. Conclusion:- This study has highlighted the common causes of haematuria in our local setting. We recommend that full and appropriate investigations be carried out on patients with frank haematuria especially those above 50 years old in order to provide earlier detection and prompt management of bladder diseases especially tumours.

• 대한교통학회지
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• 제27권4호
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• pp.55-61
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• 2009

차종분류는 교통의 흐름 및 안전에 미치는 영향을 분석하고 도로의 포장 및 시설의 설계를 위하여 이루어진다. 국내에서는 국토해양부의 12종 분류에 따라 고속국도, 일반국도, 지방도의 차종분류 자료가 제공되고 있다. 기계식 차종분류를 위한 AVC(Automatic Vehicle Classification) 장비는 차량길이, 축거, 내민 거리(overhang) 등의 측정값과 미리 입력된 모든 차량 모델의 제원값을 비교하여 차종을 판단한다. 하지만, 기존의 방법은 센서의 관리상태에 분류 정확도가 크게 영향받게 된다. 본 연구에서는 실제 조사지점에서 발생하는 장비 오차와 차량 제원정보에 민감하지 않은 차종분류 알고리즘을 개발하였다. 알고리즘을 단순화하기 위하여 차량길이와 축거 중심으로 추세선을 이용하여 차종을 분류하므로 센서의 정확도 변화의 영향을 감소시켰다. 개발된 알고리즘의 평가를 위하여 일반국도에 설치된 AVC 장비에서 축수, 차량길이, 축거, 내민거리를 추출하여 비디오 판독 결과와 비교하였다. 실험 결과는 전체 차량에 대하여 88.2%의 정확도를 얻었다. 본 연구에서 개발된 차종분류 알고리즘은 센서의 감도 변화 등 현장 환경의 변화에 덜 영향을 받도록 설계되어 차종분류를 위한 기계식 장비의 안정적 정확도 유지에 활용될 수 있을 것으로 기대된다.

• 한국안전학회지
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• 제26권6호
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• pp.130-136
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• 2011

Since out of a lot of traffic problems traffic accidents cause damage to life and properties of people, it stands out as one of traffic problems which needs improvement, and the loss due to traffic accident negatively affects not only the parties to the accident but also the national economy. Thus, continual concern of the government toward traffic safety is getting bigger and lately each local government is preparing a basic plan for traffic safety and vitalizing traffic safety policies. As expanding the responsibility and role of local governments for traffic safety, traffic safety measures which are based on the characteristics of each local government should be studied. Most of analytical methods in the existing traffic accidents prediction models with macroscopic vision focus on socioeconomic variables such as local population and the number of registered vehicles, and present a great deal of prediction error when they are applied in practice. In this context, this study proposed a traffic accident prediction model in respect of macroscopic level for autonomous districts (administrative districts) of Seoul City. The model development was not based on the entire city but on the type of local land usage (development density) whose relationship with traffic accident frequency was analyzed.

• 대한화학회지
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• 제67권4호
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• pp.241-252
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• 2023

이 연구는 학생들이 어려워하는 화학의 여러 개념 중 하나인 동적 평형에 대한 학생의 이해를 높이는 것을 목적으로 한다. 동적 평형은 입자들의 끊임없는 움직임과 상호 작용을 미시적으로 이해하고, 이를 통해 발현되는 거시적인 특성을 이해할 수 있도록 실제와 표상이 겹친 준미시적 수준으로 다루어야 한다. 하지만 9종의 화학 I 교과서를 분석한 결과 평형에 대한 표현 방식은 다소 한계가 있었다. 준미시적 표상 접근을 통해 평형을 이해할 수 있는 전략으로 스크래치를 활용한 수업을 4차시로 구안 하였고, 56명 학생을 대상으로 실행하였다. 4차시 수업은 6단계로 구성이 되며, 단계적으로 평형을 이해하도록 설계하였다. 사전 검사와 사후 검사를 비교한 결과, 학생들이 화학 평형에 대해 미시적 설명과 거시적 설명을 모두 옳게 하는 학생이 크게 증가하였다. 이를 통해 준미시적 표상의 접근 방식으로 스크래치를 활용한 수업의 적용 가능성을 엿볼 수 있었다.

• 한국자동차공학회논문집
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• 제11권3호
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• pp.58-64
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• 2003

Dimethyl Ether(DME) has been considered as one of the most attractive alternative fuels for compression ignition engine. Its main advantage in diesel engine application is high efficiency of diesel cycle with soot free combustion though conventional fuel injection system has to be modified due to the physical properties of DME. Experimental study of DME and conventional diesel spray employing a common-rail type fuel injection system with a 5-hole sac type injector was performed in a constant volume vessel pressurized by nitrogen gas. Spray cone angles and penetrations of the DME spray were characterized and compared with those of diesel. For evaluation of the evaporating characteristics of the DME, shadowgraphy technique employing an Ar-ion laser and an ICCD camera was adopted. Tip of the DME spray was formed in mushroom-like shape at atmospheric chamber pressure, which disappeared in higher chamber pressure. Spray tip penetration and spray cone angle of the DME became similar to those of diesel under 3MPa of chamber pressure. Higher injection pressure provided wider vapor phase area while it decreased with higher chamber pressure condition.

• Journal of the Korean Wood Science and Technology
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• 제15권1호
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• pp.22-55
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• 1987

본(本) 연구(硏究)는 육안적(肉眼的) 특성(特性)에 의한 목재식별(木材識別)의 속보(續報)로써 앞으로 생산가능(生産可能)한 한국산(韓國産) 단판수종(單板樹種)의 현미경적(顯微鏡的) 목재특성(木材特性)을 조사(調査)하여 합판공업(合板工業)에 필요(必要)한 기초자료(基礎資料)를 제공하기 위하여 실시(實施)하였다. 선정(選定)된 50수종(樹種)의 현미경적(顯微鏡的) 특성(特性)을 조사(調査)하여 수종별(樹種別)로 기재(記載)하였고 이를 바탕으로 하여 침엽수재(針葉樹材) 및 활엽수재별(闊葉樹材別)로 목재식별(木材識別) 검색표(檢索表)를 간략(簡略)하게 보고(報告)하면 다음과 같다.

• 수산해양기술연구
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• 제52권1호
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• pp.65-71
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• 2016

Injection rate, injection quantity and injection timing of fuel are controlled precisely by electric control in CRDI system. Particularly, injection rate being influenced with injection pressure affects to spray characteristics and fuel-air ratio, so it is a very important factor in diesel combustion. In this study, injection rates in accordance with injection pressure at a constant ambient pressure were measured with Zeuch's method. Under the same condition, non-evaporating spray images were taken with a high speed camera and analyzed carefully with Adobe Photoshop CS3. Macroscopic spray characteristics and breakup processes in the spray could be found from the examined and analyzed data. Injection start time and injection period were practically affected with injection pressure. Also, initial injection rate, spray penetration, spray angle and breakup of high density droplets region in the spray were affected with injection pressure. The results and techniques of spray visualization and injection rate measurement in this study would be practically effective to study a high pressure diesel spray for common rail direct injection system.