• 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.

• 한국수자원학회논문집
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• 제53권12호
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• pp.1173-1181
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• 2020

최근 단기간의 국지성호우가 빈번하게 발생하면서 단순 1차적 피해를 넘어 경제적, 사회적 영향이 커지고 있다. 기상선진국에서는 단순 기상예보로서의 정보전달이 아닌 사회 경제적 영향을 분석하여 현실적이고 신뢰할 수 있는 영향예보를 실시하고 있다. 본 논문에서는 사람의 보행에 영향을 미칠 수 있는 영향한계강우량을 산정하기 위해서 Spatial Runoff Assessment Tool (S-RAT), FLO-2D 모델을 사용하여 침수정도를 도출하였고 Grid to Grid (G2G)개념의 한계강우량을 산정하였다. 또한, 과거 의학 분야에서 많이 사용하였지만 현재는 가뭄이나 홍수 등의 자연현상 및 머신러닝에 많이 사용하는 ROC 분석 기법을 통해 정량적인 정확도분석을 실시하였다. 분석 결과 실제 침수와 모의 침수가 비슷한 시간대의 결과가 나왔으며 ROC 곡선의 결과 0.7이상으로 Fair 단계의 적정성을 확보하였다.

• 한국축산식품학회지
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• 제41권2호
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• pp.312-323
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• 2021

The purpose of this study was to use 1H nuclear magnetic resonance (1H NMR) to quantify taste-active and bioactive compounds in chicken breasts and thighs from Korean native chicken (KNC) [newly developed KNCs (KNC-A, -C, and -D) and commercial KNC-H] and white-semi broiler (WSB) used in Samgye. Further, each breed was differentiated using multivariate analyses, including a machine learning algorithm designed to use metabolic information from each type of chicken obtained using 1H-13C heteronuclear single quantum coherence (2D NMR). Breast meat from KNC-D chickens were superior to those of conventional KNC-H and WSB chickens in terms of both taste-active and bioactive compounds. In the multivariate analysis, meat portions (breast and thigh) and chicken breeds (KNCs and WSB) could be clearly distinguished based on the outcomes of the principal component analysis and partial least square-discriminant analysis (R2=0.945; Q2=0.901). Based on this, we determined the receiver operating characteristic (ROC) curve for each of these components. AUC analysis identified 10 features which could be consistently applied to distinguish between all KNCs and WSB chickens in both breast (0.988) and thigh (1.000) meat without error. Here, both 1H NMR and 2D NMR could successfully quantify various target metabolites which could be used to distinguish between different chicken breeds based on their metabolic profile.

• 한국융합학회논문지
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• 제13권3호
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• pp.33-41
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• 2022

본 논문에서는 다중 요인을 고려한 천연 가스 누출 정도 예측을 위해 관련 요인을 포함하는 기상청 자료와 천연가스 누출 자료를 통합하고, 요인 분석을 기반으로 중요 특성을 선택하는 머신러닝 기법을 제안한다. 제안된 기법은 3단계 절차로 구성되어 있다. 먼저, 통합 데이터 셋에 대해 선형 보간법을 수행하여 결측 데이터를 보완하는 전처리를 수행한다. 머신러닝 모델 학습 최적화를 위해 OrdinalEncoder(OE) 기반 정규화와 함께 요인 분석을 사용하여 필수 특징을 선택하며, 데이터 셋은 k-평균 클러스터링으로 레이블을 지정한다. 최종적으로 K-최근접 이웃, DT(Decision Tree), RF(Random Forest), NB(Naive Bayes)의 네 가지 알고리즘을 사용하여 가스 누출 수준을 예측한다. 제안된 방법은 정확도, AUC, 평균 표준 오차(MSE)로 평가되었으며, 테스트 결과 OE-F 전처리를 수행한 경우 기존 기법에 비해 성공적으로 개선되었음을 보였다. 또한 OE-F 기반 KNN(OE-F-KNN)은 95.20%의 정확도, 96.13%의 AUC, 0.031의 MSE로 비교 알고리즘 중 최고 성능을 보였다.