• 한국대기환경학회지
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• 제23권5호
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• pp.547-556
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• 2007

The release, sampling and analytical methods have been developed and tested for perfluorocarbons (PFCs) atmospheric tracers in order to gain insight into the atmospheric transport and dispersion over the urban conditions of Seoul, Korea. Although PFCs tracer experiments provide unique opportunities to test local and urban scale of transport and dispersion, no previous experiment with PFCs has been conducted in Korea. PMCH and PDCH were chosen as targeted tracers in our study due to their extreme low ambient concentrations and great sensitivities among various PFCs. For PFCs release system, a set of micro-metering pump, electronic balance, vaporizing furnace and high speed blower was constructed for precise and accurate release of tracers. The precision of released rate by this system was estimated to be 1%. Samplings of PFCs were carried out by fabricated portable air samplers with micro pumps and rotameters into glass tubes packed with 150 mg of Carboxen-569. The uncertainty of these sampling system was maintained below 14%. PMCH and PDCH were quantified in GC/ECD with preconditioned injection system to eliminate the interference compounds using traps and subsequent catalytic conversion system prior to column separation. Three intensive field test were undertaken during the springtime of 2002 to 2004 in eastern part of Seoul. Daily background samples were collected to characterize the background levels of PMCH and PDCH prior to their release. The observed background concentrations of PMCH ranged from 3.5 to 10.1 fL/L and varied randomly in location and time in this study. Its mean and standard variation of background concentration ($6.8{\pm}1.9\;fL/L$) are higher than those ($3.2{\sim}5.8\;fL/L$) of other historic tracer studies. Identified uncertainty for background PMCH was $1.7{\sim}2.0\;fL/L$ using this analytical system. Combined relative uncertainty in determining the tracer's concentrations was estimated as 17%. However, its background concentrations and uncertainty in concentration determination were found to be low and stable enough for tracer study.

• 터널과지하공간
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• 제26권4호
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• pp.274-282
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• 2016

현재 국내에서 가행 중인 석회석 광산은 자연환기력을 주된 환기방법으로 사용하고 있고, 대단면 굴착으로 매우 저속의 공기유동현상이 나타나고 있다. 이로 인하여 작업구간의 공기질이 매우 저하되어 있는 실정이다. 이러한 문제점들을 개선하기 위해서는 먼저 환기성능을 면밀하게 평가할 필요가 있다. 본 연구에서는 이러한 환기성능평가를 위해서 추적가스법을 적용하여 평가를 실시하였다. 연구 결과, 추적가스법을 통해 매우 저속의 공기유동, 공기재순환현상, 작업장 공기교환율 등을 정량적으로 평가함에 따라서 연구광산의 환기문제점들을 정밀하게 확인할 수 있었다. 이러한 추적가스법을 활용한 환기성능 평가방법은 광산의 작업환경 개선을 위하여 매우 정밀한 도구로 사용될 수 있음을 확인하였다.

• 대한치과보철학회지
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• 제40권6호
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• pp.560-571
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• 2002

Jaw relations and the recording methods have been controversial aspects of dentistry. The purpose of this study was to quantify the relative muscle activity of the masseter and temporal muscles in relation to different intermaxillary relations recorded by intra-oral tracer during maximal clenching and to decide the optimal mandibular position. Ten volunteers with healthy TMJ were studied. Intra-oral tracer was assembled and bite block was fabricated in the articulator. Intra-oral tracer was placed in the mouth, and four mandibular positions were recorded. EMG activity was recorded on a BIO-PAK system (Bio-Research Associates, Inc. USA.) in masseter and temporal muscle and compared in each mandibular positions. The results were as follows: 1. In comparison with maximum intercuspation, the chewing position was the most similar followed by tapping position, myocentric position and posterior border position. However the differences were not statistically significant. 2. In comparison of bilateral symmetry of masseter muscle, tapping position was the most symmetrical followed by chewing position and maximum intercuspation. Myocentric position and posterior border position were not symmetrical. (P<.05). 3. In comparison of bilateral symmetry of anterior temporal muscle, chewing position was the most symmetrical followed by posterior border position, maximum intercuspation, myocentric position and tapping position. However the differences were not statistically significant. 4. In comparison of proportionality of anterior temporal muscle to masseter muscle activity on left side, posterior border position was the greatest followed by myocentric position, taping position, chewing position and maximum intercuspation. And the proportionality of posterior border position was greater than that of maximum intercuspation. (P<.05). 5. In comparison of proportionality of anterior temporal muscle to masseter muscle activity on right side, myocentric position was the greatest followed by posterior border position, tapping position, maximum intercuspation and chewing position. However the differences were not statistically significant.

• 대한토목학회논문집
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• 제29권1B호
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• pp.35-45
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• 2009

본 연구에서는 사행수로에서 유속구조가 추적물질의 혼합에 미치는 영향을 분석하기 위하여 2개의 만곡부를 갖는 S자형 실험수로를 제작하여 순간 주입된 추적자물질에 대한 분산실험을 수행하였다. 실험자료를 분석한 결과, 주 흐름은 사행수로의 최단경로를 따라 이동하며 만곡부에서 불균일한 분포를 갖는 것으로 밝혀졌다. 이차류의 경우, 만곡부에서 강력한 셀이 발달하나 직선부에서는 소멸하다가 다시 다음 만곡부에 반대 방향의 셀로 재생성됨이 확인되었다. 오염운의 거동은 주흐름의 불균일한 분포와 이차류셀에 의해 매우 큰 영향을 받는 것으로 나타났다. 주흐름의 불균일한 분포는 오염운을 종방향으로 분리시키고, 이차류 셀은 만곡부 외측의 처진 오염운을 횡방향으로 더욱 분리시키는 역할을 하게 되어, 결과적으로 만곡부의 복잡한 유속구조가 오염운을 종 횡방향으로 모두 분리시키고 나아가서 많이 퍼지게 하는 작용을 하는 것으로 밝혀졌다. 2차원 추적법의 적용을 통해서 각 케이스별 종 횡분산계수 실측치를 산정한 결과, 사행수로 전체구간에 대한 무차원 횡분산계수는 0.012~0.875의 범위를 갖는 것으로 밝혀졌다. 횡분산계수는 하폭 대 수심비에 대체적으로 비례하는 것으로 나타났다. 횡분산계수 이론식에 의한 추정치와 비교한 결과, 이론치가 실측치와 비교하여 다소 과대 산정하는 경향을 보여주고 있음을 알 수 있었다.

• Journal of Advanced Marine Engineering and Technology
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• 제29권7호
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• pp.736-743
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• 2005

In this study, three different types of mechanical ventilation systems are compared based on their ventilation characteristics: tracer gas concentration decay characteristics, and ventilation effectiveness by calculating actual ventilation air flow rate. The experiments are performed by using a step-down method for measuring tracer gas. $CO_{2}$ gas, concentration in the model chamber. Application of a mixing factor, k, was used and measured values ranged from 0.68 to 0.77. The Type 2 ventilation system was found to have the highest ventilation effectiveness rather than the Types 1 and 3.

• KIEAE Journal
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• 제4권3호
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• pp.103-107
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• 2004

This paper aims for evaluating the wind-driven ventilation in basement parking lots of apartment. Wind tunnel tests coupled with tracer gas method were conducted, and classified by wind directions and opening types. The test results showed that, as for wind-driven ventilations, stack type openings were more successful than scuttle vent. Finally, according to Weibull distribution in Seoul, yearly averaged wind-driven ventilation rate was calculated.

• 한국의학물리학회지:의학물리
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• 제26권1호
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• pp.18-27
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• 2015

컴프턴 산란 현상을 이용하여 전자적 집속 방법으로 영상화하는 컴프턴카메라는 고민감도 및 고에너지 해상도의 장점을 이용하여 핵의학 응용분야에 대한 잠재력이 큰 영상 시스템이다. 본 논문에서는 컴프턴카메라를 이용한 다중 추적자 영상의 효용성 평가와 정확한 3차원 단면영상 촬영을 위한 Orlov 조건을 만족하는 회전하는 컴프턴카메라의 구조를 조사하였다. 140/511 keV의 방사선원의 소프트웨어 모형을 구성하고 이에 대한 몬테카를로 전산모사 시뮬레이션을 수행하여 리스트모드 배열된 부분집합 기댓값 최대화 방법으로 재구성된 다중 추적자 영상으로 컴프턴카메라의 효용성을 검증하였다. 산란부와 흡수부를 평행하게 위치시킨 고정된 컴프턴카메라와 촬영대상 주위 $360^{\circ}$를 회전하는 컴프턴카메라를 구성하여 검출된 투사선의 구좌표계 각도에 대한 히스토그램을 비교 평가하였다. 140/511 keV의 동시 계측된 몬테카를로 전산모사 데이터의 다중 추적자 영상이 2차원 및 3차원 재구성 시 잘 구분되는 것을 확인하였으며, 회전된 컴프턴카메라의 경우, 회전각도에 반비례하여 3차원 영상재구성에 필요한 유효 투사선이 증가하였다. 26분의 계산 시간 및 5백만개의 적절한 유효 투사선의 개수를 고려할 때 컴프턴카메라의 회전각은 $30^{\circ}$가 현실적으로 적절할 것이며 증가한 검출 시간은 다중 컴프턴카메라를 구성하여 해결할 수 있다. 본 논문에서 고찰한 고민감도 및 고에너지 해상도를 가진 컴프턴 카메라는 다중추적자 영상화를 위해 적합한 시스템이며 생화학 및 생리학적 상태 변화에 대한 임상 정보를 제공하며 각종 질병 진단 및 치료 방법 개발 등에 기여할 수 있는 잠재력이 있는 영상 시스템이다.

• 한국지하수토양환경학회지:지하수토양환경
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• 제19권3호
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• pp.111-122
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• 2014

Partitioning interwell tracer test (PITT) is a method to quantify and qualify a site contaminated with NAPLs (Non-Aqueous Phase Liquids). Analytical description of PITT assumes that the injection-pumping well pair is on the line of the ambient groundwater flow direction, but the test-well pair could frequently be off the line in a real field site, which could be an erroneous factor in analyzing PITT data. The purpose of this work is to study the influence of the angle of the test-well pair on the ambient groundwater flow direction based on the result from PITT. From the experiments, it was found that the obliqueness of the test-well pair to the ambient groundwater flow direction could affect the tracer test resulting in a decreased NAPL estimation efficiency. In case of an oblique arrangement of the test-well pair to the ambient flow direction, it was found that the injection of a chase fluid could enhance the estimation efficiency. An increase of the pumping rate could enhance the recovery rate but it cannot be said that a high pumping rate can increase the test efficiency because a high pumping rate cannot give partitioning tracers enough time to partition into NAPLs. The results have a implication that because the arrangement of the test-well pair is a controlling factor in performing and interpreting PITT in the field in addition to the known factors such as heterogeneity and the source zone architecture, flow direction should be seriously considered in arranging test-well pair.

• 보건행정학회지
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• 제3권1호
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• pp.25-52
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• 1993

Variation in the utilization of medical services is a very important issue in cost containment and quality assurance of health care. Practice variation directly affects health care expenditure especially in fee-for-service system, which is the payment system of health insurance in Korea. In addition to cost issue it is generally accepted that variations in medical practice and the cost of inpatient care suggest the possibility of inappropriate quality of care. This study is to closely examine the patterne and degrees of variation in cost structure of inpatient care among types of hospital and individual hospitals in some tracer diseases, and also to inquire into the service items which contribute much to the variation of total medical care cost. Foru common diseases, i.e. Cesarean Section, appendectomy, cataract extraction and pediatric pneumonia, were selected as tracer diseases. In most tracer diseases there were statistically significant differences in total medical care cost among hospitals in same type of hospital as well as among types of hospital(p<0.01). When total medical care cost were subdivided into the types of service, cost of medication and diagnostic examination varied the most prominenly. When the cost of medication were subdivided again, cost of parenteral antibiotics showed the most prominent variation. Of total medical care cost, medication was most contributory to the variation of total medical care cost(58.1~82.3%), and cost of antibiotics was most contributory to the variation of medication cost(63.9~92.2%). The results of study implicated that reducing the variation of medication may plays a significant role in containing the cost of inpatient care. In order to sort out the factors affecting practice variations including drug prescription pattes further researches are required.

• 한국지하수토양환경학회지:지하수토양환경
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• 제27권3호
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• pp.22-40
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• 2022

The goal of this study was to estimate the possible scattering distance of deicer from the highway and the impact range of deicer on soil quality in terms of plant growth. Among the major elements (Ca²⁺, Cl^- and Na⁺) of deicer, Ca²⁺and Cl^- are usually applied as fertilizer to soil. Therefore both elements (Ca²⁺and Cl^-) were not appropriate for a tracer of deicer at the agricultural area. In this study, SAR (sodium adsorption ratio) of soil was proposed as an alternative tracer to confirm the distribution of the deicer around the highway areas. Because deicer is the main anthropogenic source of Na⁺ around the highway areas and does harm to the physical properties of soil and plant growth through the destruction of soil aggregate, SAR would be an recommendable tracer to access the distribution of deicer as well as adverse effect on soil quality at highway areas. The influence range of deicer based on SAR of soil was estimated to be less than 20 m distance from the highway even though the possible flying distance of deicer was found to be more than 100 m from the highway. However the deicer seriously deposited within 10 m from the highway.