• 대한방사선치료학회지
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• 제29권2호
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• pp.101-108
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• 2017

목 적: 양성자치료에 이용되는 양성자선은 종양 부위 앞에 있는 정상 조직에는 적은 선량을 주는 반면 암 조직 부위에서는 브래그 피크(Bragg peak)를 형성하며 최대 선량을 주고 바로 소멸하는 특징을 가지고 있으며 양성자치료의 장점을 극대화하기 위해서는 양성자의 도달 위치 검증이 매우 중요하다. 본 연구에서는 Off-line PET CT 방법을 이용하여 양성자 조사 후 양성자 궤적을 따라 생성된 11 C(반감기=20분), 150(반감기=2분), 13N (반감기=10분) 등의 핵자에서 방출되는 양전자의 분포를 측정하여 양성자의 Range와 Distal falloff 지점을 검증하게 되었다. 대상 및 방법: IEC 2001 Body 팬텀안에는 37 mm, 28 mm, 22 mm 구체를 삽입할 수 있게 구성되어 있으며 팬텀안에 물을 가득 채워 각 구체크기별로 CT image를 획득하였고 양성자의 Range와 Distal falloff 지점을 검증하기 위하여 양성자치료계획시스템으로 각 구체 크기 별로 37 mm 구체에서 46 mm, 28 mm에서 37 mm, 22 mm 구체에서 33 mm의 SOBP를 설정하였고, Scanning 방법으로 Gantry 0도의 Single beam으로 동일한 센터에서 양성자를 조사하였다. 조사된 팬텀은 PET-CT 장비를 이용하여 스캔하였고, PET-CT 영상획득방법은 1분씩 50개의 영상을 획득하여 팬톰 내의 구체를 포함하여 4개의 ROI를 설정한 후 10개씩 영상을 합산하여 재구성 하였다. 치료계획 시 수립한 구체크기에 따른 Dose profile과 비교하기 위하여 Depth에 따른 Activity profile로 나타냈다 결 과: 37 mm, 28 mm, 22 mm 구체에서 모두 Distal falloff position 에서 Dose profile과 같이 PET-CT의 Activity profile 역시 급격히 감소하는 양상을 나타냈다. 하지만 Range를 평가하는 구간인 SOBP구간에서는 Activity profile의 경우 Proximal 부분에서의 측정치가 Dose profile 양상과 다른 결과가 나왔으며, Distal falloff position을 구체 크기별로 양성자 치료계획과 PET-CT 측정치와의 차이를 비교해 본 결과 37 mm 구체에서는 Max dose의 50 % 지점에서 최대 1.4 mm, 28 mm 구체에서는 45 % 지점에서 최대 1.1 mm, 22 mm 구체에서의 차이는 40 % 지점에서 최대 1.2 mm로 모두 1.5 mm 미만의 차이를 보였다. 결 론: 양성자치료의 장점을 최대한 활용하기 위해서는 양성자빔의 Range를 검증하는 것이 매우 중요하다. 본 연구에서는 PET-CT 장비를 이용하여 양성자빔의 SOBP 와 Distal falloff 위치를 통해 양성자 Range를 확인하였고 그 결과 PET-CT 장비를 이용해 측정한 Activity 분포와 양성자 치료계획과의 Distal falloff position의 차이는 1.4 mm 내에서 일치함을 확인하였다. 이는 본원에서 양성자치료계획 시 적용하는 선량마진에 참고자료로 활용될 수 있을 것으로 사료된다.

• 한국해양공학회지
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• 제22권5호
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• pp.44-51
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• 2008

The planning and design of coastal structures against wave attack is required to accurately predict wave transformation, wave run-up, and fluid. particlevelocities an a slope. On tire other hand, in tire swash and surf zones of a natural beach, where coastal erosion and accretion occur at tire land-sea boundary, hydrodynamic analysis is essential. In this study, a RBREAK2 numerical model was created based on the nonlinear shallow water equation and laboratory measurements were carried out in terms of tire free surface elevations and velocities for tire cases of regular and irregular waves on 1 : 10 and 1 : 5 impermeable slopes. The data were used to evaluate tire applicability and limitations of tire RBREAK2 numerical model. The numerical mode1 could predict tire cross-shore variation of the wave profile reasonably well, but showed more accurate results for slopes that were steeper than 1 : 10. Except near tire wave crest, tire computed depth averaged velocities could represent tire measured profile below tire trough level fairly well.

• 한국해양공학회지
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• 제32권5호
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• pp.351-360
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• 2018

The construction of large scale harbor structures at Maengbang beach, which is located on the eastern coast of Korea, is of great concern because it may cause disastrous beach erosion in the vicinity. Therefore, a hydraulic model experiment was conducted to examine the morphological changes after such construction. The water depth was scaled using the method of Van Rijn (2010), which is a well-known scale law, but the results appeared to be overestimated. The present study developed a new scale law that applies an equilibrium beach profile formula to scale the model evolution to the prototype scale. When compared with survey data observed at Maengbang beach, the proposed method showed better agreement than the method of Van Rijn (2010).

• Structural Engineering and Mechanics
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• 제59권5호
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• pp.933-950
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• 2016

Decks, interior beams, edge beams and girders are the parts of a steel floor system. If the deck is optimized without considering beam optimization, finding best result is simple. However, a deck with higher cost may increase the composite action of the beams and decrease the beam cost reducing the total cost. Also different number of floor divisions can improve the total floor cost. Increasing beam capacity by using castellated beams is other efficient method to save the costs. In this study, floor optimization is performed and these three issues are discussed. Floor division number and deck sections are some of the variables. Also for each beam, profile section of the beam, beam cutting depth, cutting angle, spacing between holes and number of filled holes at the ends of castellated beams are other variables. Constraints include the application of stress, stability, deflection and vibration limitations according to the load and resistance factor (LRFD) design. Objective function is the total cost of the floor consisting of the steel profile cost, cutting and welding cost, concrete cost, steel deck cost, shear stud cost and construction costs. Optimization is performed by enhanced colliding body optimization (ECBO), Results show that using castellated beams, selecting a deck with higher price and considering different number of floor divisions can decrease the total cost of the floor.

• 한국토양비료학회지
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• 제24권4호
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• pp.254-259
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• 1991

요소(尿素)가 사용된 초지의 토양단면(土壤斷面)에서 pH, 인산, 유기물 그리고 치환성(置換性) 양(陽)이온 함량의 계절적 변화를 조사하였다. 질소(窒素)비료 28kg N/10a을 시용하고 무질소구(無窒素區)와 목초(牧草)를 재배하면서 봄(5.26), 여름(7.27), 가을(10.18)철에 토양시료를 100cm까지 20cm 간격으로 채취하여, 토양(土壤) 화학성(化學性)을 비교(比較)한 결과는 다음과 같다. 1 봄, 여름철에 토양깊이 0~20cm에서 28kg N/10a 처리구의 pH는 질소 무처리구에 비하여 각각 0.7, 1.0 단위 낮았으며 토양깊이 20cm 이하에서도 28kg N/10a 처리구에서 pH가 낮아졌으며 계절별 pH감소 정도는 여름>봄>가을 순(順)이었다. 2. 토양 Bray No.1 인산 함량은 봄, 여름 철 질소무처리구와 28kg N/10a 처리간에 토양깊이별 차이가 없었으나, 여름철에 0~20cm 깊이에서의 인산함량은 봄철에 비하여 약 20ppm정도 낮았다. 가을철에는 28kg N/10a 처리의 토양깊이 20cm이하에서 인산함량이 봄, 여름철에 비하여 증가(增加)되는 경향을 보였다. 3. 유기물(有機物) 함량은 가을철에 질소 무처리구, 28kg N/10a 처리에서 공히 낮아지는 경향(傾向)이었으나, 대체적으로 질소시용량별, 토양깊이별 계절간 함량변화는 매우 적었다. 4. Ca 함량은 질소 무처리구, 28kg N/10a 처리 공히 토양깊이가 깊을수록 완만하게 감소(減少)되는 경향이었으나, 28kg N/10a 처리에서는 토양깊이 0~20cm에서의 함량이 봄철에 가장 높고 다음이 여름, 가을철 순(順)이었다. Mg과 K 함량은 질소 무처리구과 28kg N/10a 처리간에 계절별, 토양깊이별 차이가 거의 없었다. 5. 여름 철에 질소 무처리구에서는 $NH_4-N$ 함량과 pH, 유기물, Ca, Mg간에 정(正)의 유의상관(有意相關)이 있었고 28kg N/10a 처리에서는 $NO_3-N$함량과 토양 pH간에 부(負)의 유의상관(有意相關)(r=$-0.534^*$)이 있었다.

• 기술사
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• 제25권4호
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• pp.102-108
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• 1992

This study was carried to find out the soil characteristics of landslide site and to develope landslide prediction method by seismic refraction prospecting. For these aims, landslide condition and travel time were investigated at 68 Landslide sites over the country during 1990 to 1991. The results were as follows. 1. The surface of rupture was included mainly in C layer. Its Hardness was less than 3kg / $\textrm{cm}^2$ at the upper pare of landslide. 2. When the profile line length was 20m, the range of travel time was 40 to 90 msec. The travel time did not differ between bedrocks. 3. Refraction distance ranged from 1 to 7m and mean of that was 2.5m. Travel time was increased according to receiving distance without large variance in the refraction distance but that was appeared large variance out of the refraction distance on slope that has shallow soil depth and discontinuous ground surface. Therefore, the spread distance must be shorten to 10-l5m. 4. The seismic velocity at the first layer(layer of rupture) was less than 500m1sec by degree of weathering and the velocity at the second layer decreased in order of Granite> Granitic gneiss >Sedimentary rock. 5. The first layer observed by seismic refraction was contained C layer that has parent material and weathered rocks of hardness 10-20kg/$\textrm{cm}^2$. 6. Among the range of seismic velocity was less than 200m/sec in 63% of the total plots, 200-300m/sec in 34% and 300-500m /sec in 3%. 7. There was a proportional relationship between seismic prospecting soil depth and executive soil depth, and seismic propection soil depth was about 10 to 20cm deeper than the order.

• Restorative Dentistry and Endodontics
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• 제37권1호
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• pp.24-28
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• 2012

Objectives: The aim of this study was to test the hypothesis, that the effectiveness of irrigation in removing smear layer in the apical third of root canal system is dependent on the depth of placement of the irrigation needle into the root canal and the enlargement size of the canal. Materials and Methods: Eighty sound human lower incisors were divided into eight groups according to the enlargement size (#25, #30, #35 and #40) and the needle penetration depth (3 mm from working length, WL-3 mm and 9 mm from working length, WL-9 mm). Each canal was enlarged to working length with Profile.06 Rotary Ni-Ti files and irrigated with 5.25% NaOCl. Then, each canal received a final irrigation with 3 mL of 3% EDTA for 4 min, followed by 5 mL of 5.25% NaOCl at different level (WL-3 mm and WL-9 mm) from working length. Each specimen was prepared for the scanning electron microscope (SEM). Photographs of the 3mm area from the apical constriction of each canal with a magnification of ${\times}250$, ${\times}500$, ${\times}1,000$, ${\times}2,500$ were taken for the final evaluation. Results: Removal of smear layer in WL-3 mm group showed a significantly different effect when the canal was enlarged to larger than #30. There was a significant difference in removing apical smear layer between the needle penetration depth of WL-3 mm and WL-9 mm. Conclusions: Removal of smear layer from the apical portion of root canals was effectively accomplished with apical instrumentation to #35/40 06 taper file and 3 mm needle penetration from the working length.

• Journal of Welding and Joining
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• 제25권3호
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• pp.85-91
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• 2007

The conventional study on the laser surface transformation hardening has been carried out with a beam of the specified shape and uniform power-intensity distribution in order to ensure the uniformity of the hardening depth. Two types of beams - the circular gaussian beam and rectangular beam of the uniform power-intensity distribution were used in this study. we were supposed to optimize the process parameters and to compare the hardening results with two optics respectively. As a result, the hardness distribution of the hardened zone was similar in both cases and the hardened phase by the rectangular beam was denser than that by the circular gaussian beam.

• International Journal of Advanced Culture Technology
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• 제10권1호
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• pp.211-229
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• 2022

In this study, we aimed to define the effects of anthropomorphism and conversational relevance of chatbots on user experience. In specific, the chatbot designed for this study was an online shopping assistant that recommends items for consumers. Levels of anthropomorphism was manipulated by the name, profile picture, word choices, and emojis, while conversational relevance was adjusted by the depth and accuracy of the recommendation. Three categories of user experience were measured: psychological distance, usability, and purchase intentions. The results implied a significant main effect of conversational relevance on all variables for the high anthropomorphized conditions, while all but psychological distance was significant for low anthropomorphized conditions. Although there was no significant main effect of anthropomorphism observed for the variables, the main effect of anthropomorphism on responsibility was marginally significant for a specific item. The results of this study may function as a guidance for future studies regarding usage of chatbots within a marketing setting.

• Asian Pacific Journal of Cancer Prevention
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• 제15권8호
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• pp.3779-3784
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• 2014

Aims: To study alterations of plasma lipid profiles in carcinoma cervix and to assess significance comparedwith controls in different histological grades and stages. Materials and Methods: Totals of 99 histopathologically diagnosed cases and 35 controls from a tertiary hospital situated in the southern part of India which caters the rural and semi-urban populations were considered for the study. Fasting blood samples were taken to analyze total cholesterol (TC), triglycerides (TG), high density lipoprotein cholesterol (HDL-C) and low density lipoproteins cholesterol (LDL-C), for comparison of cases, grouped according to histological grades and stages, and controls. One way ANOVA was used for multiple group comparisons and the Student's t test (unpaired) for group wise comparisons. For all tests a 'p' value of 0.05 or less was considered as significant. Results: Out of 99 cases, most (n-39) were seen in the 40-49 year age group followed by 60-69 years (n-22). Serum TG significantly differed between cases and controls but without any relation to differentiation grade. The lipid profile parameters in various grades of cervical cancer were not statistically significant. Statistically significant increase of TC and LDL-C values was observed with increase in stage of the disease. Conclusions: The study showed TG is elevated in cervical cancer, and that TC and LDL-C are proportional to the spread of cancer as it increases from stage I to stage IV. An in-depth study of molecular changes in lipid metabolism in cervical cancer patients, enzymes/genes responsible and alterations in LDL receptors is necessary to provide information to decide whether the lipid profile has any diagnostic/prognostic role in cervical cancer.