• Radiation Oncology Journal
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• 제31권4호
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• pp.228-233
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• 2013

Purpose: The aim of this study was to evaluate changes in breast tumor bed volume during whole breast irradiation (WBI). Materials and Methods: From September 2011 to November 2012, thirty patients who underwent breast-conserving surgery (BCS) followed by WBI using computed tomography (CT) simulation were enrolled. Simulation CT scans were performed before WBI (CT1) and five weeks after the breast irradiation (CT2). The tumor bed was contoured based on surgical clips, seroma, and postoperative change. We retrospectively analyzed the factors associated with tumor bed volumetric change. Results: The median tumor bed volume on CT1 and CT2 was 29.72 and 28.6 mL, respectively. The tumor bed volume increased in 9 of 30 patients (30%) and decreased in 21 of 30 patients (70%). The median percent change in tumor bed volume between initial and boost CT was -5%. Seroma status (p = 0.010) was a significant factor in tumor bed volume reduction of 5% or greater. However, patient age, body mass index, palpability, T stage, axillary lymph node dissection, and tumor location were not significant factors for tumor bed volumetric change. Conclusion: In this study, volumetric change of tumor bed cavity was frequent. Patients with seroma after BCS had a significant volume reduction of 5% or greater in tumor bed during breast irradiation. Thus, resimulation using CT is indicated for exquisite boost treatment in breast cancer patients with seroma after surgery.

• 대한기계학회논문집B
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• 제22권4호
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• pp.468-480
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• 1998

The temporal and spatial distributions of soot volume fractions were measured for single toluene droplet flames as a function of pressure under the normal-gravity condition. In order to characterize the transient nature of the flame and sooting regions, a full-field light extinction and subsequent tomographic inversion technique was used. The reduction in sooting as a function of pressure was assessed by comparison of the maximum soot volume fractions at several vertical positions along the axis above the droplet. The maximum soot volume fraction was reduced by 70% when the pressure was reduced by 60% from 1 atm to 0.4 atm. The reduction in sooting is attributed to variation of the geometric configuration of flame which reduces the system Grashof number as well as only the change in the adiabatic flame temperature as the pressure decreases. The gravimetrically-measured total soot yield was also compared to the optically-measured soot volume fraction to obtain a correlation between the two measurements. As a result, the total soot yield was linearly proportional to the optically-measured maximum soot volume fraction and linearly reduced as the pressure decreased. Accordingly, the non-intrusive full-field light extinction-measurements were able to be calibrated not only to measure soot volume fraction, but to simultaneously evaluate the total soot yield emitted from the toluene droplet flame (which is useful in the practical application).

• Archives of Plastic Surgery
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• 제41권5호
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• pp.520-528
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• 2014

Background As the breast cancer incidence has increased, breast-conserving surgery has replaced total mastectomy as the predominant procedure. However, centrally located breast cancers pose significant challenges to successful breast-conserving surgeries. Therefore, we performed partial mastectomy and oncoplastic procedures on centrally located breast cancer as a means of partial breast reconstruction. The authors examined and evaluated the functional and aesthetic usefulness of this reconstruction method. Methods From January 2007 to June 2011, 35 patients with centrally located breast cancers who underwent various oncoplastic procedures based on the breast size and resection volume. The oncoplastic procedures performed included volume displacement surgical techniques such as purse-string suture, linear suture, and reduction mammaplasty. Other oncoplastic procedures included volume replacement procedures with an adipofascial, thoracoepigastric, intercostal artery perforator, thoracodorsal artery perforator, or latissimus dorsi flap. Results Mean patient age was 49 years, and mean follow-up period was 11 months. In cases of small to moderate-sized breasts and resection volumes <50 g, volume displacement procedures were performed. In cases of resection volumes >50 g, volume replacement procedures were performed. In cases of larger breasts and smaller resection volumes, glandular reshaping was performed. Finally, in cases of larger breasts and larger resection volumes, reduction mammaplasty was performed. This reconstruction method also elicits a high patient satisfaction rate with no significant complications. Conclusions In centrally located breast cancer, oncoplastic surgery considering breast size and resection volume is safe and provides appropriate aesthetic outcomes. Therefore, our method is advisable for breast cancer patients who elect to conserve their breasts and retain a natural breast shape.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2003년도 춘계학술대회논문집
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• pp.719-724
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• 2003

The present experimental study deals with noise reduction and improvements in cooling performance in a plasma display panel(PDP) television (TV). To reduce the noise, the effects of installation parameters are studied. The experimental parameters under investigation are the distance between the fan and the rear case of a PDP TV, position of the strut on the fan, and the fan RPM. The variance of RPM is the most significant facto., and a 250 RPM decrease from 910 RPM causes about 4㏈(A) reduction in the system noise. To increase performance, flow characteristics are investigated by using a visualization technique and measuring the volume flow rate. The visualized results show that a radial direction flow due to large system resistance is significant, and an axial velocity oscillation is observed from the measurement of the volume flow rate. To prevent both a radial direction flow and an axial velocity oscillation, sponges are inserted in the space between f3n and the rear case. Inserted sponges improve the volume flow rate of cooling fans up to 32% since they convert a radial direction flow to an axial direction flow. Also an axial velocity oscillation with large amplitude and low RPM disappears. Increasing volume flow rate causes the PDP TV to improve its cooling performance. Additionally the same volume flow rate can be obtained with a decreased fan speed due to the inserted sponge. Noise reductions of 4.2 ㏈(A) at the rear and 1.1 ㏈(A) at the front of the TV are obtained by the decreased RPM. An increase of 10% of the volume flow rate is also achieved by inserting sponges.

• 한국음향학회지
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• 제38권1호
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• pp.67-72
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• 2019

본 연구에서는 파장보다 작은 구조물로 이루어진 음향메타물질을 이용하여 소형화된 헬름홀츠 공진기의 반향음 감소 성능예측 연구를 진행하였다. 본 논문에서 제안된 헬름홀츠 공진기는 수중 환경과 임피던스 차이가 큰 공기구조물로 형성하였다. 다중물리 유한요소 시뮬레이션 패키지를 이용하여 수중 음향학적 분석을 진행한 결과 수중 반향음의 감소가 예상되었고 헬름홀츠 공진기 입구의 공간 압축(space coiling) 정도와 내부 체적의 폭에 따라 주파수 특성을 제어할 수 있었다. 기본적인 헬름홀츠 공진기는 약 10,000 Hz 이상에서 최대 7 dB의 반향음 감소 효과를 보였으나 공간 압축 메타물질을 이용한 초소형 헬름홀츠 공진기는 약 5,000 Hz 이상에서 최대 14 dB의 반향음 감소가 나타났다. 추가적으로 헬름홀츠 공진기의 내부 체적을 제어하여 주파수 특성이 변화하는 것을 확인하고 공간압축 비율이 서로 다른 공진기를 조합함으로써 광대역 반향음 감소 효과를 얻을 수 있었다. 본 연구를 통해 수중 환경에서 공기구조물을 이용한 소형화된 헬름홀츠 공진기의 성능을 연구하였으며 반향음 감소 효과는 효과적인 스텔스 기술을 구현할 수 있을 것으로 기대된다.

• 대한방사선기술학회지:방사선기술과학
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• 제40권1호
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• pp.127-134
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• 2017

본 연구는 실내 라돈 가스의 농도를 낮추기 위한 방법을 찾기 위해 건물의 준공연도, 건물의 용적, 환기 세 가지 변수에 따른 실내 라돈 농도를 비교, 측정하여 그 영향을 알아보고자 한다. 측정은 1973년에 건축이 되었고, 2011년에 증축이 된 건물의 6층을 대상으로 용적이 서로 다르고 준공연도가 1973년과 2011년인 6개의 강의실을 측정하였다. 준공연도에 따른 라돈농도를 비교하기 위해 4개의 강의실을 선정하였고, 용적에 따른 라돈농도를 비교하기 위해 준공연도가 같고 용적이 다른 강의실을 선정하였고, 환기에 따른 라돈농도를 비교하기 위해 6개의 강의실의 폐쇄와 환기를 시행하였다. 결과적으로 준공연도에 따른 라돈농도는 최근에 지어진 건물에서 라돈농도가 최대 4배 높게 나타났으며, 용적에 따른 라돈농도는 용적이 작을수록 높게 나타났다. 환기에 따른 라돈농도의 변화는 폐쇄 시보다 환기를 할 경우 약 80%의 감소율을 보였다. 특히, 준공연도가 최근이면서 용적이 작을수록 라돈농도가 높게 검출되었고, 세 가지 변수 중 환기가 라돈농도 감소에 가장 큰 영향을 끼쳐 라돈에 의한 피폭감소 효과를 기대할 수 있을 것으로 사료된다.

• Bulletin of the Korean Chemical Society
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• 제31권1호
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• pp.100-103
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• 2010

In this study, NO reduction behaviors of copper-loaded mesoporous molecular sieves (Cu/MCM-41) have been investigated. The Cu loading on MCM-41 surfaces was accomplished by a chemical reduction method with different Cu contents (5, 10, 20, and 40%). $N_2/77$ K adsorption isotherm characteristics, including the specific surface area and pore volume, were studied by BET's equation. NO reduction behaviors were confirmed by a gas chromatography. From the experimental results, the Cu loading amount on MCM-41 led to the increase of NO reduction efficiency in spite of decreasing the specific surface area of catalysts. This result indicates that highly ordered porous structure in the MCM-41 and the presence of active metal particles lead the synergistical NO reduction reactions due to the increase in adsorption energy of MCM-41 surfaces by the Cu particles.

• 한국분말야금학회:학술대회논문집
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• 한국분말야금학회 2006년도 Extended Abstracts of 2006 POWDER METALLURGY World Congress Part2
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• pp.1331-1332
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• 2006

The present investigation has attemped to optimize hydrogen reduction process for the mass production of Fe-8wt%Ni nanoalloy powder from ball milled $Fe_2O_3-NiO$ powder. In-situ hygrometry study was performed to monitor the reduction behavior in real time through measurement of water vapor outflowing rate. It was found that the reduction process can be optimized by taking into account the apparent influence of water vapor trap in the reactor on reduction kinetics which strongly depends on gas flow rate, reactor volume and reduction.

• 한국의학물리학회:학술대회논문집
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• 한국의학물리학회 2003년도 제27회 추계학술대회
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• pp.63-63
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• 2003

Purpose: Planning target volume (PTV) for tumors in abdomen or thorax includes enough margin for breathing-related movement of tumor volumes during treatment. We developed a simple and handy method, which can reduce PTV margins in patients with moving tumors, respiratory motion reduction device system (RMRDs). Materials and Methods: The patients clinical database was structured for moving tumor patients and patient setup error measurement and immobilization device effects were investigated. The system is composed of the respiratory motion reduction device utilized in prone position and abdominal presser (strip device) utilized in the supine position, moving phantom and the analysis program, which enables the analysis on patients setup reproducibility. It was tested for analyzing the diaphragm movement and CT volume differences from patients with RMRDs, the magnitude of PTV margin was determined and dose volume histogram (DVH) was computed using a treatment planning software. Dose to normal tissue between patients with RMRDs and without RMRDs was analyzed by comparing the fraction of the normal liver receiving to 50% of the isocenter dose(TD50). Results: In case of utilizing RMRDs, which was personally developed in our hospital, the value was reduced to $5pm1.4 mm$, and in case of which the belt immobilization device was utilized, the value was reduced to 3$pm$0.9 mm. Also in case of which the strip device was utilized, the value was proven to reduce to $4pm.3 mm$0. As a result of analyzing the TD50 is irradiated in DVH according to the radiation treatment planning, the usage of the respiratory motion reduction device can create the reduce of 30% to the maximum. Also by obtaining the digital image, the function of comparison between the standard image, automated external contour subtraction, and etc were utilized to develop patients setup reproducibility analysis program that can evaluate the change in the patients setup. Conclusion: Internal organ motion due to breathing can be reduced using RMRDs, which is simple and easy to use in clinical setting. It can reduce the organ motion-related PTV margin, thereby decrease volume of the irradiated normal tissue.

• Journal of Korean Neurosurgical Society
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• 제39권2호
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• pp.92-95
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• 2006

Objective : Severe vertebral body collapse [vertebra plana] is considered a contraindication to vertebroplasty by most authors. The purpose of this study is to determine the efficacy of vertebroplasty in treating severe compression fracture patients with osteoporosis. Methods : 16 patients underwent 18 vertebroplasties following postural reduction for vertebra plana. The fractures were defined vertebrae that have collapsed to more than 75% of their original height. Imaging and clinical features were analyzed, including involved vertebrae level, vertebral height after postural reduction for 2 days, injected cement volume, clinical outcome and complications. Results : Involved veretebra were located from level T7 to L4. Vertebral body collapse averaged 79% [range $12{\sim}25%$] of the original height. After pillow reduction for 2 days, vertebral body height increased 35% of the original height [range $15{\sim}45%$]. The kyphotic wedge was $12^{\circ}$ before procedure and was decreased $7.0^{\circ}$ after vertebroplasty. The mean injected cement volume was 3.8ml [range $2.0{\sim}4.9ml$]. After the procedure, surgical outcome was excellent in 8 [50%] of 16 patients, good in 7 [42%] and unchanged in one [8%]. The mean pain score [VAS score] prior to vertebroplasty was 8.3 and it changed 3.2 after the procure. Cement leakage to the adjacent disc [5 cases] and paravertebral soft tissues [4 cases] developed but there were no major complications. Conclusion : We propose that vertebra plana due to osteoporosis is not a contraindication to vertebroplasty. Vertebroplasty following postural reduction for severe compression fracture is safe and effective treatment.