• Journal of Gastric Cancer
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• 제10권4호
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• pp.241-246
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• 2010

Purpose: Laparoscopy-assisted gastrectomy (LAG) has become a technically feasible and safe procedure for early gastric cancer treatment. LAG is being increasingly performed in many centers; however, there have been few reports regarding LAG at low-volume centers. The aim of this study was to report our early experience with LAG in patients with gastric cancer at a low-volume center. Materials and Methods: The clinicopathologic data and surgical outcomes of 39 patients who underwent LAG for gastric cancer between April 2007 and March 2010 were retrospectively reviewed. Results: The mean age was 68.3 years. Thirty-one patients had medical co-morbidities. The mean patient ASA score was 2.0. Among the 39 patients, 4 patients underwent total gastrectomy and 35 patients underwent distal gastrectomy. The mean blood loss was 145.4 ml and the mean operative time was 259.4 minutes. The mean time-to-first flatus, first oral intake, and the postoperative hospital stay was 2.8, 3.1, and 9.3 days, respectively. The 30-day mortality rate was 0%. Postoperative complications developed in 9 patients, as follows: anastomotic leakage, 1; wound infection, 1; gastric stasis, 2; postoperative ileus, 1; pneumonia, 1; cerebral infarction, 1; chronic renal failure, 1; and postoperative psychosis, 1. Conclusions: LAG is technically feasible and can be performed safely at a low-volume center, but an experienced surgical team and careful patient selection are necessary. Furthermore, for early mastery of the learning curve for LAG, surgeons need education and training in addition to an accumulation of cases.

• 전자공학회논문지CI
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• 제48권5호
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• pp.55-63
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• 2011

본 논문은 방위각 및 고저방향으로 카메라 움직임이 있는 감시장치의 비디오 프레임 연속영상을 1)각각 $N{\times}M$ 개의 서브블록으로 나눈 후 각각의 서브블록에 대해 FFT 위상상관 기법을 적용하여 이동표적 위치를 구하고, 2)연속영상을 정합 후 차영상을 구하여 적응 문턱 값을 적용해서 표적후보군을 구하였으며, 3)두 기법을 적용하여 클러터를 제거하는 새로운 표적탐지기법을 제안하였다. 블록 내 다양한 크기의 영상 움직임이 있을 경우 FFT 위상상관 기법은 적용하여 움직임을 구하면 큰 영상의 움직임이 가장 큰 위상상관 값으로 나타나는 특성을 이용하여 배경환경에 강인한 이동표적 위치(블록)탐지를 하였다. 또한, 차영상을 영상분리하기 위한 적응 문턱 값은 카메라 움직임 등 배경환경 변화를 고려한 학습가중치를 이용하여 구하였다. 제안된 알고리즘 성능입증은 다양한 배경환경에서 카메라 이동/정지조건에서 다양한 이동표적에 대해 탐지 가능함을 시뮬레이션을 통해 확인하였으며 탐지성능은 ROC 커브를 통해 확인하였다.

• 융합신호처리학회논문지
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• 제6권1호
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• pp.15-22
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• 2005

본 논문은 CCD 칼라 영상을 이용하여 얼굴을 인식할 수 있는 방법을 제안한다. YCbCr 컬러모델에서 피부색에 대한 색상 정보와 적응적인 피부범위 확장을 통하여 얼굴후보영역을 추출하였다. 추출된 얼굴후보영역을 이용하여 곡선전개 방식의 초기곡선으로 사용하여 얼굴영역을 정확히 추출하였다. 얼굴의 특징점을 추출하기 위하여 얼굴영역에서 칼라정보를 이용한 Eye Map과 Mouth Map을 이용하였다. Log-polar변환의 중심점을 얻기 위하여 검출된 얼굴의 특징점을 이용하였다. 특징벡터를 추출하기 위하여 DCT, 웨이브렛 변환을 통하여 추출한 계수들을 이용하였다. 제안된 방법의 타당성을 검토하기 위하여 BP 학습알고리즘을 사용하는 신경망에서 얼굴인식을 수행하였다. 실험결과, 제안한 방법이 입력영상의 회전, 크기변화에 대하여 기존의 방법에 비하여 강인한 인식결과를 얻을 수 있었다.

• Archives of Reconstructive Microsurgery
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• 제14권2호
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• pp.105-111
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• 2005

Perforator flaps have become increasingly popular in microsurgery nowadays and are being used widely for many cases of reconstruction after trauma and cancer ablation. And thoracodorsal perforator based free flap is one of them having the merits of carrying a large skin paddle with leaving intact innervation and function of the remaining latissimus dorsi muscle. We made a homogeneous thin flap excluding the main muscle with a long vascular pedicle and tried to decrease the donor site morbidity. But, it needs a long learning-curve and we have met marginal flap necrosis frequently. Besides, prolonged operation time for complete perforator dissection may be a tedious job to the microsurgeon. To overcome these disadvantages, we usually included very small portion of the latissimus dorsi muscle during this flap elevation around the pedicled 2-3 thoracodorsal perforators during this flap elevation. We performed 3 cases of thoracodorsal perforator based free flap at Hallym university sacred heart hospital between May and August 2005 for the soft tissue defect of the scalp and feet. The average flap size was $8{\times}14\;cm$. Although it is not a true perforator flap, we can get the reliability for the flap survival with much better blood circulation and save the time of one or two hours to dissect the perforators completely. All cutaneous flaps survived completely without any complication except one fatty female who had the very small superficial fat necrosis due to flap bulkiness. We believe the thoracodorsal perforator based free flap can be extended its versatility and reliability by including the very small portion of the muscle around the perforators.

• 유통과학연구
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• 제13권1호
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• pp.7-18
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• 2015

Purpose - This study integrates a corporate competition system with a bird predation system to examine how organizational strategic adjustment capacity influences firm performance. By proving the prominent effects on performance, a financial vector is constructed to represent corporate strategic adjustment results, and an operation capacity vector is constructed, which can be categorized as a parameter for locating birds. All these works help us to propose a new method of investment, the portfolio decision model based on the strategic adjustment capacity. Research design, data, and methodology - Strategic adjustment capacity can be decomposed into three aspects: the organizational learning capacity from the top firms, the extent to which firms maintainor rely on the best operational capacity vector in history, and the ability to eliminate the disadvantages or retain the advantages of the operation capacity vector from the previous year. The method of solving cyclic equations is designed to evaluate strategic adjustment. Firms manufacturing specialized equipment are chosen to test the effects of the strategic adjustment capacity on three aspects of firm performance. Results - There is a positive correlation between the capacity to learn from the best firms and performance improvement. The relationship between the dependence or maintenance of a firm's advantages and performance improvement is a U-shape curve, and there is no significant effect of inertial control on performance improvement. Conclusions - A firm's competition system is a sophisticated adaptation, and competitive advantage and performance can be investigated based on the principles of competition in nature.

• 대한의생명과학회지
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• 제25권1호
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• pp.99-106
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• 2019

Amyloid positron emission tomography (PET) allows early and accurate diagnosis in suspected cases of Alzheimer's disease (AD) and contributes to future treatment plans. In the present study, a method of implementing a diagnostic system to distinguish ${\beta}$-Amyloid ($A{\beta}$) positive from $A{\beta}$ negative with objectiveness and accuracy was proposed using a machine learning approach, such as the Principal Component Analysis (PCA) and Support Vector Machine (SVM). $^{18}F$-Florbetaben (FBB) brain PET images were arranged in control and patients (total n = 176) with mild cognitive impairment and AD. An SVM was used to classify the slices of registered PET image using PET template, and a system was created to diagnose patients comprehensively from the output of the trained model. To compare the per-slice classification, the PCA-SVM model observing the whole brain (WB) region showed the highest performance (accuracy 92.38, specificity 92.87, sensitivity 92.87), followed by SVM with gray matter masking (GMM) (accuracy 92.22, specificity 92.13, sensitivity 92.28) for $A{\beta}$ positivity. To compare according to per-subject classification, the PCA-SVM with WB also showed the highest performance (accuracy 89.21, specificity 71.67, sensitivity 98.28), followed by PCA-SVM with GMM (accuracy 85.80, specificity 61.67, sensitivity 98.28) for $A{\beta}$ positivity. When comparing the area under curve (AUC), PCA-SVM with WB was the highest for per-slice classifiers (0.992), and the models except for SVM with WM were highest for the per-subject classifier (1.000). We can classify $^{18}F$-Florbetaben amyloid brain PET image for $A{\beta}$ positivity using PCA-SVM model, with no additional effects on GMM.

• 대한치과의사협회지
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• 제56권11호
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• pp.631-640
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• 2018

Nowadays computer-guided "flapless" surgery for implant placement using templates is gaining popularity among clinicians and patients. The advantages of this surgical protocol are its minimally invasive nature, accuracy of implant placement, predictability, less post-surgical discomfort and reduced time required for definitive rehabilitation. Aim of this study is to describe the digital implant protocol, thanks to which is now possible to do a mini-invasive static guided implant surgery. This is possible thanks to a procedure named surface mapping based on the matching between numerous points on the surface of patient's dental casts and the corresponding anatomical surface points in the CBCT data. With some critical points and needing an adequate learning curve, this protocol allows to select the ideal implant position in depth, inclination and mesio-distal distance between natural teeth and or other implants enabling a very safe and predictable rehabilitation compared with conventional surgery. It represents a good tool for the best compromise between anatomy, function and aesthetic, able to guarantee better results in all clinical situations.

• 스마트미디어저널
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• 제9권4호
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• pp.126-133
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• 2020

병원에서는 폐암 환자의 최종병기를 기준으로 치료방침 및 예후를 결정하고 있다. 폐암 환자의 최종병기는 미국 암 연합회(AJCC)에서 제공하는 TNM 분류방법을 바탕으로 7단계로 나누어 진단된다. 이런 접근 방법은 환자의 치료, 예후 및 생존일 예측 등 다양한 분야에서 사용하기에 한계가 있다. 이 논문에서는 데이터 과학적 접근을 통해 T, N, M병기를 사용하여 생존일수별 환자집단을 나눌 수 있는지 알아보기 위해 비지도 학습 중 하나인 군집분석(Clustering)을 진행한 후 군집분석의 결과를 Cox비례위험모형을 사용하여 비교 하였다. 환자들의 최종병기를 사용하지 않고, T, N, M병기 정보만 사용하였을 때 생존시간 예측정확도가 더 높은 것을 확인하였다. 특히, AJCC의 최종병기 7단계와 같이 군집의 개수를 7로 설정했을 때보다 군집의 수를 축소하거나 확장했을 때 T, N, M 병기 군집분석을 통한 생존시간 예측정확도가 향상하는 것을 확인하였다.

• 디지털융복합연구
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• 제19권2호
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• pp.161-168
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• 2021

지식기반경제로의 이행이 가속화되기 시작하면서 기업 환경에 많은 변화가 일어나고 있다. 중국제조 2025 전략을 시작으로 중국 산업에도 변화가 일어나기 시작하였다. 제조공장으로서의 역할이 아닌, 첨단기술 기반의 산업을 선도하기 위한 노력을 경주하고 있다. 본 연구의 목적은 중국 기업의 혁신에 대한 결과물인 전유 메커니즘을 파악하는데 있다. 이를 위해 본 연구에서는 선행연구를 기반으로 델파이 조사를 통해 8개 요인을 최종적으로 도출하고, 8개 요인을 중국 기업의 실무자들을 대상으로 전유 메커니즘에 대해 설문조사를 하였다. 분석결과, 전체산업을 기준으로 전유 메커니즘의 중요성은 특허, 의장등록, 리드타임, 비밀유지, 보완적 제조, 보완적 판매 및 서비스, 디자인의 복잡성, 학습곡선 효과/규모의 경제 순으로 그 중요도가 나타났다. 본 연구의 결과는 기업의 실무자들이 자사에게 맞는 전유 메커니즘을 통해 기업의 지식재산 전략의 계획을 수립하는데 도움을 줄 수 있을 것으로 보인다.

• Journal of Gastric Cancer
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• 제21권2호
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• pp.179-190
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• 2021

Purpose: Reduced port laparoscopic distal gastrectomy (RPLDG) using 3 ports is less invasive than conventional laparoscopic distal gastrectomy (CLDG) using 5 ports. Although RPLDG performed by expert surgeons is safe and feasible, novice surgeons have difficulty performing this procedure. This study evaluated the surgical outcomes and feasibility of RPLDG performed by a novice surgeon. Materials and Methods: The records of 136 patients who underwent laparoscopic distal gastrectomy for gastric cancer performed by a single novice surgeon between May 2016 and December 2018 were retrospectively reviewed. Among these 136 patients, 52 underwent RPLDG and 84 underwent CLDG. The clinicopathological characteristics, operative outcomes, and short-term postoperative outcomes of the 2 groups were compared. Results: The percentage of women was significantly higher in the RPLDG group than in the CLDG group (48.1% vs. 31%; P=0.045), but other baseline characteristics did not differ significantly between the groups. Billroth II anastomosis was performed significantly more frequent (90.4% vs. 73.8%, P=0.015) and operation time was significantly shorter (207.1±43.3 min vs. 225.5±44.6 min, P=0.020) in the RPLDG group than in the CLDG group. The time to first flatus, postoperative pain score, length of postoperative hospital stay, and incidence and severity of complications did not differ significantly between the groups. Analysis of the learning curve based on the operation time showed that performing RPLDG on 20-30 patients was required to achieve technical proficiency. Conclusions: RPLDG is a safe and feasible surgical procedure for the treatment of gastric cancer, even when performed by a novice surgeon.