Risk Factors of Tissue-Expander Infection in Breast Reconstruction

Purpose: Implant-based breast reconstruction has multiple advantages such as decreased morbidity, shorter operative time and faster recovery. However, postoperative infection with tissue expander increases medical cost and causes a delay in concurrent antineoplastic treatment. To reduce tissue expander infection, it is important to identify related risk factors and minimize them when possible. Methods: A retrospective review of patient records in a single breast cancer center was performed. Eighty-six tissue expanders were placed in 80 women for postmastectomy breast reconstruction. Variables including patients'age, body mass index (BMI), preoperative breast volume, operation time, drain indwelling time, postoperative seroma/hematoma formation, chemotherapy, and radiation therapy were evaluated. Infection was defined as the status that shows any symptom of local inflammation and identification of pathogens. Representative values were compared through Student's t-test and univariate and multivariate analyses. Results: We examined 86 postmastectomy tissueexpanders which were placed between June 2004 and April 2010. Seven cases of tissue expander infection (8.1%) were identified. The infected tissue expander was removed in three of the cases. The relationship between BMI, and preoperative breast volume and that between infection and non-infection groups were significant ($p$ <0.05). Univariate analysis showed significant association between BMI ($p$=0.023) and preoperative breast volume ($p$=0.037). Multivariate analysis revealed that BMI and preoperative breast volume were independent variables regarding tissue expander infection. Conclusion: Certain characteristics of implant-based breast reconstruction patients increase infection rate of tissue expander. These risk factors should be monitored and evaluated before surgeries for more successful outcome.ope

Landmark-based particle localization algorithm for mobile robot with fish-eye vision system

학위논문(석사) - 한국과학기술원 : 로봇공학학제전공, 2009. 8., [ viii, 58 p. ]위치 추정은 자율적인 로봇에게 중대한 능력이고 로봇 공학 연구 분야의 주요 흐름 중 하나 이다. 표식점을 이용한 위치 추정은 위치에 대한 사전 정보 없이 위치 추정이 가능하다. 그래서 로봇의 동작 정보에서 오는 심각한 누적 위치 오차를 극복할 수 있고 로봇을 누군가 옮긴 후에도 바로 위치 추정을 할 수가 있다. 전방향 비전 시스템은 많은 정보를 얻을 수 있기 때문에 로봇 비전 시스템으로 자주 사용되지만, 비싸고 구하기 어렵다는 단점이 있다. 하지만 이 논문에서 사용한 어안렌즈 비전 시스템은 싸고 구하기 쉽다. 어안렌즈 비전 시스템은 전방향 비전 시스템과 비교해서 많은 표식점 정보를 얻을 수 없기 때문에 적은 표식점 정보로 위치 추정하는 알고리즘이 필요하다. 이 논문에서는 표식점 기반 위치 추정 입자 알고리즘을 제안한다. 표식점의 각도, 거리 정보를 이용하여 가능한 범위를 계산하고 가능한 범위 안에 분포된 입자의 적합도를 계산하여 로봇의 위치를 추정한다. 제안된 알고리즘을 시뮬레이션과 실제 로봇 실험으로 검증하였다. 시뮬레이션에서 제안된 알고리즘의 정확도와 정밀도를 Shimshoni 위치 추정 알고리즘과 RANSAC, MLESAC, u-MLESAC을 적용하여 개선된 Shimshoni 위치 추정 알고리즘과 비교하였다. 실제 로봇 실험에서 어안렌즈 비전 시스템을 장착한 전방향 이동 로봇을 사용했고 강인한 결과를 보였다.한국과학기술원 : 로봇공학학제전공

Estimations and Long-term Trend of Sea-to-air Dimethyl Sulfide (DMS) Flux using Satellite Observation Data

The long-term linear trend of global sea-to-air dimethyl sulfide (DMS) flux was analyzed over a 16-year time span (2000~2015), based on satellite observation data. The emission rates of DMS (i.e. DMS flux) in the global ocean were estimated from sea surface DMS concentrations, which were constructed with chlorophyll a (Chl-a) concentrations and mixed layer depths (MLD), and transfer velocity from sea to air, which was parameterized with sea surface wind (SSW) and sea surface temperature (SST). In general, the DMS flux in the global ocean exhibited a gradual decreasing pattern from 2000 (a total of 12.1 Tg/yr) to 2015 (10.7 Tg/yr). For the latitude band (10o interval between 0o and 60o), the DMS flux at the low latitude of the Northern (NH) and Southern hemisphere (SH) was significantly higher than that at the middle latitude. The seasonal mean DMS flux was highest in winter followed by in summer in both hemispheres. From the longterm analysis with the Mann-Kendall (MK) statistical test, a clear downward trend of DMS flux was predicted to be broad over the global ocean during the study period (NH: −0.001~−0.036 μmol/m2/day per year, SH: −0.011~−0.051 μmol/m2/day per year). These trend values were statistically significant (p < 0.05) for most of the latitude bands. The magnitude of the downward trend of DMS flux at the low latitude in the NH was somewhat higher than that at the middle latitude during most seasons, and vice versa for the SH. The spatio-temporal characteristics of DMS flux and its long-term trend were likely to be primarily affected not only by the SSW (high positive correlation of r = 0.687) but also in part by the SST (r = 0.685).33scopuskc