특성도를 이용한 결측치 대체방법

김형주,김동재,Kim, Hyungju,Kim, Dongjae 한국통계학회 2017 응용통계연구 Vol.30 No.3

임상시험에서 어떻게 결측치를 다룰 것인가 하는 것은 큰 문제이다. 주로 주분석에서 사용하는 ITT원칙은 결측치가 어떠한 메커니즘을 따른다는 가정 하에 결측치를 대체 하지만 가정에 대한 타당성이 불확실한 문제가 있다. 즉, 올바른 결측치 대체방법은 매우 중요하다. 본 연구에서는 Kang과 Kim (1997)이 제안한 일치도와 유지도의 개념을 이용하여 새로운 결측치 대체방법을 제안하였다. 또한 실제자료를 이용하여 예제를 제시하고 Monte Carlo 모의실험을 통하여 기존방법과 대체 성능을 비교하였다. How to handle missing data is a main issue in clinical trials. We impute missing data based on missing data that follows a mechanism according to the intention-to-treat rule. However, using the right imputation method for missing data is very important because this supposition is unclear. We suggest a new imputation method for missing data using agreement and maintenance introduced by Kang and Kim (1997). We give an example and adapt a Monte Carlo simulation to compare the performance between the established method and the suggested method.

미생물을 이용한 대마의 리그닌과 펙틴 분해

김형주,권길광,서규원,김민철,김형섭,고준석,Kim, Hyung-Joo,Kwon, Kil-Koang,Seo, Kyu-Won,Kim, Min-Chul,Kim, Hyung-Sup,Koh, Joon-Seok 한국섬유공학회 2009 한국섬유공학회지 Vol.46 No.6

In this study, microbial degradation of lignin and pectin in raw hemp was investigated. Using lignin and pectin containing media, various microorganisms were isolated from soil and fecal samples of ruminant. The isolates were identified using the 16s rRNA method. The isolated strains were Klebsiella sp., E. coli, Aspergillus fumigatus, and Burkholderia sp. For the degradation of hemp, a pre-cultured isolate was inoculated (5% v/v) into the medium containing raw hemp (as a sole carbon source: 1% w/v) and nitrogen sources and the mixture was incubate aerobically for 168 hours in a shaking incubator (200 rev $min^{-1}$) at $30^{\circ}C$. The hemp biodegradation activity of the identified microorganism was measured by FT-IR. The FT-IR results showed that the Klebsiella sp. has the highest lignin and pectin degradation activity. These results show that the isolates and the reaction conditions could be applied to the conventional hemp fiber refinery processes.

리튬 유황전지용 폴리우레탄 고분자 전해질의 전기화학적 특성

김형주,신준호,김종화,김기원,안효준,안주현,Kim, Hyeong-Ju,Shin, Joon-Ho,Kim, Jong-Hwa,Kim, Ki-Won,Ann, Hyo-Jun,Ahn, Ju-Hyun 한국전기화학회 2002 한국전기화학회지 Vol.5 No.2

본 연구에서는 높은 인장강도와 탄성력을 가지는 다공성 폴리우레탄(polyurethane, PU)을 지지체(matrix)로 이용하고, 유기 전해액 ethylene carbonate(EC), propylene carbonate(PC), tetraethylene glycol dimethylether(TG)와 1M $LiCF_3SO_3$를 부피비 1:1 비율로 혼합하여 액체 전해액을 제조하였으며, 높은 이론용량을 가지는 Li/S전지에 적용하여 전기 화학적 특성을 조사하였다. 1M $LiCF_3SO_3$에 TG를 첨가할 경우 유기 전해액의 함침량이 약 $750\%$ 증가하였으며 방전용량$(1065mAh/g{\cdot}sulfur)$ 및 사이클 특성이 가장 우수하였다. 1M $LiCF_3SO_3$에 TG/EC(v/v,1:1) 및 PC/EC(v/v,1:1)를 첨가한 경우 이온 전도도는 각각 $3.15\times10^{-3}(S/cm)$ 와 $3.18\times10^{-3}(S/cm)$로 나타났다. Polyurethane was used as matrix for polymer electrolytes with liquid electrolyte consist of organic solvent as ethylene carbonate(EC), propylene carbonate(PC), and tetraethylene glycol dimethylether(TG) and 1M $LiCF_3SO_3$, which has high mechanical strength and porosity. Electrochemical properties fur polyurethane electrolytes with various liquid electrolytes were evaluated. The amount of immersed liquid electrolyte for TG with 1M $LiCF_3SO_3$ was increased to about $750\%$ by weight, and initial discharge capacity and cycle performance was better than others. Ionic conductivity for TG/EC(v/v,1:1) and PC/EC(v/v, 1:1) with 1M $LiCF_3SO_3$ was about $3.15\times10^{-3} S/cm, \;3.18\times10^{-3}S/cm$

과학ㆍ기술ㆍ사회 - 21세기의 과학기술, 경제논리 경계해야

김형주,Kim, Hyeong-Ju 한국과학기술단체총연합회 1999 과학과 기술 Vol.32 No.12

21세기는 과학혁명이 일어날 것이라고 과학자들은 말하고 있다. 고도로 발달된 과학기술과 그 기술에 의해 빚어진 새로운 생활모습이 나타날 것이다. 그런데 과학기술은 양날의 칼과 같아서 적절히 사용하면 우리 삶을 윤택하게 해주지만 이기적인 욕망에 칼자루를 맡기면 오히려 인류 멸망의 불씨를 제공할 수도 있다. 과학기술이 인류를 위해 쓰여지도록 하기 위해선 그 기술의 경제적 이익과 사회적 비용을 적정하게 가름할 수 있는 윤리의식 확보가 선행되어야 할 것이다.

Siewert 분류에 의한 협의의 분문부 위암(type II)과 분문하 위암(type III)의 검토

김형주,권성준,Kim Hyoung-Ju,Kwon Sung Joon 대한위암학회 2004 대한위암학회지 Vol.4 No.3

Purpose: To determine the clinical value of the Siewert classification for gastic-cancer patients in Korea, we evaluated and compared the clinicopathologic factors of type II and type III cancer. Materials and Methods: The medical records of 89 consecutive patients who had undergone surgery for an adenocarcinoma of the gastroesophageal junction (GEJ) at the Department of Surgery, Hanyang University Hospital, between Jun. 1992 and Dec. 2003 were reviewed retrospectively. Results: There were one patient with type I, 12 pateints with type II and 77 patients with type III. During the same period, 1,341 patients underwent surgery for a gastric carcinoma, so proportion of GEJ cancer being $6.6\%$. The median followup duration was 31 months (range: $2\∼135$ months), and the follow-up rate was $100\%$. Between type II and type III cancers, there were no significant differences in the clinicopathologic variables including age, sex, gross appearance, histologic type, depth of invasion, and pathologic stage. The longest diameter of the tumor was larger in type III ($6.1\pm2.1$ cm) than in type II ($3.9\pm1.1$ cm)(P=0.001). A total gastrectomy with Roux-en-Y esophagojejunostomy was done most frequently, while jejunal interposition was done in 3 cases of type II and 2 cases of type III. More than a D2 lymphadenectomy was done all cases. The numbers of dissected lymph nodes and metastatic lymph nodes in type II were 43.8 and 5.8 respectively, while they were 49.8 and 8.1 in type III, but the difference between the two groups were not statistically significant. The mean length of the proximal resection margin was $15\pm5$ mm in type II and $21\pm13$ mm in type III, but this difference was not statistically significanct. The time to recurrence after operation was 19.3 months in type II and 16.9 months in type III. The five-year survival rates of type II and III were $68.8\%\;and\;52.7\%$ respectively, but difference was not significant. Conclusion: There were no significant differences in the clinicopathologic variables, including survival rate, between type II and type III cancers in Korean patients According to these findings, it appears to be reasonable to classify type III cancer as a cardia cancer in a broad sense.

상류 후류의 익렬 유동에 미치는 영향에 대한 실험적 연구

김형주,조강래,주원구,Kim, Hyeong-Ju,Jo, Gang-Rae,Ju, Won-Gu 대한기계학회 2001 大韓機械學會論文集B Vol.25 No.3

This paper is concerned with the effect of cylinder wakes upstream on blade characteristics of compressor cascade(NCA 65 series). At first, it is found that the velocity defect ratio of cylinder wake varies according to the acceleration and deceleration in a flow field but, is conserved nearly constant at flow downstream the cascade, irrespective of the flow path in the cascade. When a cylinder wake flows along near the suction surface of the blade, or impinges on the leading edge, the turbulent velocities are supplied on or inside the outer edge of boundary layer near the leading edge of suction surface, and the transition to a transitional or turbulent boundary layers is induced, so that the laminar separation is prevented, but the profile loss increases. The transition of boundary layer to a transitional or turbulent one is strongly related with the strength of added turbulent velocities near the leading edge on the suction surface, which is influenced by the flow path of a cylinder wake.

보리 잎과 옥수수 수염의 혼합과 유산균 발효를 이용한 γ-aminobutyric acid 생산 증진

김형주,윤영걸,Kim, Hyung-Joo,Yoon, Young-Geol 한국유기농업학회 2017 韓國有機農業學會誌 Vol.25 No.1

GABA는 glutamic acid decarboxylase에 의해서 L-glutamic acid가 탈탄산화되어 생합성된 비단백질 아미노산이다. GABA는 식물에서 스트레스에 대항한 대응반응으로 생성된다. 사람의 중추신경계에서는 주요 억제성 신경전달물질 중 하나로 항고혈압, 항당뇨 효능이 있다고 알려져 있다. 본 연구에서 우리는 보리 잎과 옥수수 수염을 유산균과 함께 발효함으로써 GABA 생성을 증진시키고자 하였다. 보리 잎과 옥수수 수염을 다양한 무게 비율로 조합하여 혼합하였고, $30^{\circ}C$에서 48시간 동안 배양기 안에서 L. plantarium과 함께 발효시켰다. 발효된 혼합물을 열수 추출한 후, thin layer chromatography와 GABase assay를 이용하여 GABA의 생산을 분석하였다. 우리는 9:1 혼합발효추출물이 다른 비율의 추출물 보다 GABA 함량이 높은 것을 확인하였는데 이것은 혼합과 발효기술이 보리 잎과 옥수수 수염 내 GABA 양 증진에 효과가 있음을 의미한다. 또한 몇 가지 생리활성을 분석한 결과 혼합발효추출물의 항산화 효능이 비발효 추출물에 비하여 증진되었고 세포독성은 나타나지 않음을 확인하였다. 이러한 결과는 보리 잎과 옥수수 수염의 조합과 이것을 유산균과 함께 발효시키는 방법이 고함량의 GABA와 증진된 생리 활성을 지닌 기능성 식품으로서의 개발 가능성이 있음을 의미한다. ${\gamma}$-aminobutyric acid (GABA) is a non-proteinogenic amino acid biosynthesized through decarboxylation of L-glutamic acid by glutamic acid decarboxylase. GABA is believed to play a role in defense against stress in plants. In humans, it is known as one of the major inhibitory neurotransmitters in the central nervous system, exerting anti-hypertensive and anti-diabetic effects. In this report, we wanted to enhance the GABA production from the barley leaf and corn silk by culturing them with lactic acid bacteria (LAB). The barley leaf and corn silk were mixed with various weight combinations and were fermented with Lactobacillus plantarum in an incubator at $30^{\circ}C$ for 48 h. After extracting the fermented mixture with hot water, we evaluated the GABA production by thin layer chromatography and GABase assay. We found that the fermented mixture of the barley leaf and corn silk in a nine to one ratio contained a higher level of GABA than other ratios, meaning that the intermixture and fermentation technique was effective in increasing the GABA content. We also tested several biological activities of the fermented extracts and found that the extracts of the fermented mixture showed improved antioxidant activities than the non-fermented extracts and no indication of cytotoxicity. These results suggest that our approach on combining the barley leaf and corn silk and its fermentation with LAB could lead to the possibility of the development of functional foods with high levels of GABA content and improved biological activities.

양성 라텍스를 이용한 도공층 구조의 최적화

김형주,황석우,박규재,이용규 ( Hyung Ju Kim,Seok Woo Hwang,Kyu Jae Park,Yong Kyu Lee ) 한국산림과학회 1997 한국임학회 학술발표논문집 Vol.1997 No.-

무선 센서 네트워크환경에서 헤드 경험정보를 이용한 에너지 효율적인 클러스터 헤드 선정 알고리즘

김형주,김성철,Kim, Hyung-Jue,Kim, Seong-Cheol 한국정보통신학회 2009 한국정보통신학회논문지 Vol.13 No.3

In wireless sensor networks, there are hundreds to thousands of small battery powered devices which are called sensors. As sensors have a limited energy resources, there is a need to use it effectively. A clustering based routing protocol forms clusters by distributed algorithm. Member nodes send their data to their cluster heads then cluster heads integrate data and send to sink node. In this paper we propose an energy efficient cluster-head selection algorithm. We have used some factors(a previous cluster head experience, a existence of data to transmit and an information that neighbors have data or not) to select optimum cluster-head and eventually improve network lifetime. Our simulation results show its effectiveness in balancing energy consumption and prolonging the network lifetime compared with LEACH and HEED algorithms. 무선 센서 네트워크에서는 노드들이 제한적인 에너지를 가지고 있기 때문에 효율적인 에너지 사용이 요구된다. 클러스터링 방식은 클러스터를 형성하고 클러스터 멤버 노드들이 전송한 데이터를 클러스터 헤드가 병합하여 싱크 노드로 전송하는 방식을 사용한다. 본 논문에서는 무선 센서 네트워크 환경에서 클러스터 헤드를 효율적인 선정하는 알고리즘을 제안한다. 제안하는 알고리즘은 노드 자신의 과거 헤드 경험의 세분화와 전송할 데이터의 존재 여부, 전송할 데이터를 보유하고 있는 이웃 노드들의 정보를 이용하여 헤드를 선정 함으로 네트워크 전체의 수명을 증가시킨다. 시뮬레이션을 통하여 기존의 방식인 LEACH, HEED 알고리즘에 비해 밸런싱 있는 에너지를 소모하고, 더 나은 네트워크 수명을 보장함을 보였다.

사회적 기업가정신에 대한 사회적 자본의 매개효과가 사회적 성과에 미치는 영향

김형주,전인오,Kim, Hyung-Ju,Jeon, In-Oh 한국벤처창업학회 2017 벤처창업연구 Vol.12 No.5

The purpose of this study is to examine whether the social capital supported by social enterprises play a role in ensuring self-sustaining and sustainable growth, and to examine whether the mediating effect of social capital have a central effect on social performance. The results of this study are as follows: Innovation and orientation-to-social-value of social entrepreneurship have positive effects on structural capital, and positive influence on cognitive capital and relational capital, but innovation only has no effect. In addition, social entrepreneurship is partially mediated by structural capital. In the mediating effect between social entrepreneurship and cognitive capital, only the risk-taking and the orientation-to-social-value have a partial mediation effect on cognitive capital. However, only the initiative of relational capital was found to have a full mediating effect. And social capital has a positive effect on social performance as a whole. In conclusion, considering that the realization of economic purpose and other social purpose of social enterprises will help to develop and create jobs in the local community, and that they are engaged in business activities in a poor management environment, to provide policy support for inducing high value-added industries through industry-specific collaborations.