다양한 통신 링크에서 고성능 TCP에 관한 연구

김상미,최선완,한선영,Kim, Sang-Mi,Choe, Seon-Wan,Han, Seon-Yeong 한국정보처리학회 2002 정보처리학회논문지 C : 정보통신,정보보안 Vol.9 No.2

지난 20년 동안 인터넷의 핵심 기술로서 Transmission Control of Protocol(TCP)는 데이터 전송 기능을 성공적으로 수행한 것으로 평가된다. 신뢰성 있는 데이터 전송을 수행하기 위해서 TCP는 양방향이 동일한 특성을 갖는 유선통신망을 가정하고 있고, 특히 패킷 손실의 원인을 네트워크의 혼잡(congestion)으로 가정하여 slow start, congestion avoidance, fast retransmit, fast recovery 알고리즘을 적용하고 있다. 그러나 무선이동통신망과 위성통신망에서는 패킷 손실이 링크 자체의 에러 또는 핸드오프에 의한 순간적인 접속단전에 의해서 발생되고, ADSL과 같은 비대칭형 통신망은 양방향이 다른 링크 특성을 갖는다. 따라서 다양한 통신망의 링크 특성에 따라 TCP의 기능은 수정되거나 새롭게 구현되어야 한다. 본 논문에서는 유무선 링크와 위성 링크에서의 기존 TCP 문제를 분석하고, IETF Performance Implication of Link Characteristics(PILC) WG[2]에서 권고한 TCP 표준 메커니즘을 분석하고, 이에 대한 성능을 Network Simulator 2(NS-2)를 이용하여 분석한다. Transmission Control Protocol (TCP) [1] has been tuned as a reliable transfer protocol for traditional networks comprising wired links and stationary hosts with same link characteristics. TCP assumes that congestion in the network be a primary cause for packet losses and unusual delays. TCP performs welt over such networks adapting to end-to-end delays and congestion losses, by standard congestion control mechanisms, such as slow-start, congestion avoidance, fast retransmit and recovery. However, networks with wireless and other lossy links suffer from significant losses due to bit errors and handoffs. An asymmetry network such as ADSL has different bandwidth for both directions. As a result, TCP's standard mechanisms incur end-to-end performance degradation in various links. In this paper, we analyze the TCP problems in wireless, satellite, and asymmetry links, and measure the new TCP mechanisms that are recommended by IETF Performance Implications of Link Characteristics (PILC) WG[2], by using Network Simulator 2 (NS-2).

다양한 가상 골 결함에 따른 공진 주파수의 비교 분석

김상미,박찬진,이양진,장범석,조리라,Kim Sang-Mi,Park Chan-Jin,Yi Yang-Jin,Chang Beom-Seok,Cho Lee-Ra 대한치과보철학회 2005 대한치과보철학회지 Vol.43 No.4

Purpose: Resonance frequency analysis (RFA) , a non-invasive technique for the clinical measurement of implant stability, was investigated. Peri-implant bony defect may contribute to implant failure. This in vitro study evaluated the resonance frequencies according to various bony defects and determined whether the directional bone defect can affect the value of frequency analysis. Material and Method: Fifteen 3.75 mm in diameter and 10 mm in length, machined self-tapping implant future were used. Twelve types of bone defects that have different horizontal and vertical dimensions were simulated. Embedded implants were attached to the dental surveyor. Then, the transducer was connected with the implant fixture and the ISQ value was measured at four different directions. Two-way analysis of variance and post hoc $Sch\`{e}ffe'$ test were performed at the 95% significance level. Results: The control group showed the highest ISQ value and 5 thread-$360^{\circ}$ group had the lowest one. As the vertical exposure of implants in each angle was increased, the ISQ value was decreased. Although the horizontal exposure in each thread was increased, the ISQ value was not significantly decreased. Conclusion : Although the simulated defect type was different from each other, the ISQ value was similar among groups.

짚신나물 열수 추출물의 α-Glucosidase 저해 효과 및 근육세포에서 포도당 이용에 미치는 영향

김상미,이영민,김미주,남송이,김성희,장환희,Kim, Sang-Mi,Lee, Young Min,Kim, Mi-Ju,Nam, Song-Yee,Kim, Sung-Hee,Jang, Hwan-Hee 한국식품영양학회 2013 韓國食品營養學會誌 Vol.26 No.4

본 연구는 짚신나물 열수 추출물의 ${\alpha}$-glucosidase 저해 활성을 측정하고, 분화된 근육세포에서 glucose 이용과 인슐린 신호전달에 미치는 영향을 분석하였다. 짚신나물 열수 추출물($10mg/m{\ell}$)은 ${\alpha}$-glucosidase 활성을 67% 저해하였으며, 같은 농도의 양성대조구인 acarbose(63%)와 유사한 저해 효과를 보였다. 짚신나물 열수 추출물이 ${\alpha}$-glucosidase에 의한 단당류 생성을 저해함으로 식사 후 혈당이 급격히 상승하는 것을 억제하는데 효과적인 소재로 이용 가능성을 확인하였다. 또한 근육세포에서 인슐린 저항성을 유발하기 위해 지방산(1 mM, palmitic acid)를 처리하였고, glucose의 세포내 유입이 감소되는 것을 확인하였다. 지방산 처리 세포 모델에서 짚신나물 열수 추출물($10{\mu}g/m{\ell}$)은 glucose 이용을 유의적으로 회복시켜 주었다. Normal 상태의 배양조건에서 근육세포의 포도당 이용능은 짚신나물 열수 추출물($100{\mu}g/m{\ell}$) 처리에 의해 유의적으로 증가하였다. 근육세포 내로 glucose 유입은 운반 단백질인 Glut4를 통해 이루어지며, 이것은 인슐린이 신호전달을 통해 조절한다. 짚신나물 열수 추출물의 세포 내 glucose 이용 증가 효과는 인슐린 신호전달 관련 분자인 Akt 유전자와 단백질 발현을 증가시킨 것과 관련되는 것으로 추정된다. 결론적으로, 짚신나물 열수 추출물은 소화기관에서의 탄수화물 흡수 저해와 근육세포 내 glucose 이용 증가를 통해 혈당 조절 및 당 대사 개선에 긍정적인 영향을 미치고 있음을 확인하였다. Agrimonia pilosa Ledeb. is a medicinal plant with anti-tumor, anti-oxidant, anti-inflammatory and anti-hyperglycemic activities. However, few studies of the anti-diabetic effect of A. pilosa on insulin resistance status have been performed. In the present study, the anti-diabetic effect of A. pilosa water extract (AP) was determined by investigating its ${\alpha}$-glucosidase inhibitory property, glucose utilization, and uptake, as well as insulin resistance mechanism of action in C2C12 skeletal muscle cells. Compared to positive control (acarbose), AP ($10mg/m{\ell}$) showed a similar ${\alpha}$-glucosidase inhibitory capacity. Glucose uptake was significantly increased by $1{\mu}m$ insulin treatment (p<0.05). However, palmitic acid (FFA, 1 mM) induced muscle insulin resistance and glucose uptake dysfunction. On the other hand, AP ($10{\mu}g/m{\ell}$) was capable of reversing the FFA-induced insulin resistance in C2C12 myotubes. Compared to control, AP ($100{\mu}g/m{\ell}$ without insulin) significantly increased the utilization of glucose (p<0.05) in C2Cl2 myotubes cultured in normal glucose (7 mM). AP treatment significantly increased the relative mRNA and protein expression levels of Akt. In particular, the effect of A. pilosa on the insulin signaling system is associated with the up-regulation of Akt genes and glucose uptake in C2Cl2 myotubes. These results suggest that A. pilosa is useful in the prevention of diabetes and the treatment of hyperglycemic disorders.

녹혈이 빈혈유발 Mouse에 미치는 영향

김상미,하혜경,홍순복,김정숙,Kim, Sang-Mi,Ha, Hye-Kyung,Hong, Soon-Bok,Kim, Chung-Sook 한국한의학연구원 2004 한국한의학연구원논문집 Vol.10 No.1

Hematopoietic stem cells in bone marrow form all kinds of blood cells. In traditional medicine, functions of bone marrow cells are very similar to those of Essence(精) which is a fundamental factor of physical development and reproduction. Our experiment examined the effect of deer blood on aplastic anemia induced mouse using cyclophosphamide 150 mg/kg i.p injection before experiment and then another cyclophosphamide 120 mg/kg i.p injection on day 10. Then we administrated dried deer blood in distilled water for 5 days, 9 days and 10 days. We examined blood and marrow samples. In results, deer blood showed a trend of effectiveness on recovery of red blood cells and erythropoietin although they were not statistical significant. And deer blood did not show changes in CD34.

식품첨가물 Risk Communication 전략 모형 개발 및 교육용 홈페이지 구축

김상미(Sang Mi Kim),김정원(Jeong Weon Kim) 대한지역사회영양학회 2010 대한지역사회영양학회지 Vol.15 No.2

The purpose of this research was to develop risk communication (RC) strategy and educational web-site on food additives for elementary students and their parents to improve their perception on food additives and dietary life. First of all, a survey was conducted from 1,200 elementary children and their parents to diagnose the perception and information needs on food additives. The survey revealed that most children and their parents did not have enough knowledge on food additives and demanded the safety information on food additives. Second, previous researches on food communication were analyzed to develop a risk communication model, and it was directly applied in this study. Third, a web site (www.foodnara.go.kr/foodaddy) was developed to upload the education materials along with up-to-date information and classroom activities for teachers on food additives. Fourth, the developed homepage was evaluated by applying to about 100 children and parents each, and majority of them showed high levels of understanding (children 85.7%, parents 79%) and satisfaction (children 77.2%, parents 64%), and the effect of getting over the prejudice against food additives was observed. The RC model developed in this study could be applied to any food risk communication, and the content and materials in this web site including booklets, animations, and quiz could be used effectively to promote the communication on food additives. In the future, it will be necessary to advertise the web site to be utilized by various consumer levels and to update the contents continuously by developing consumer-friendly communication materials. (Korean J Community Nutrition 15(2): 240~252, 2010)

남·북한 지방행정체제의 비교분석과 개편방향

김상미 ( Sang Mi Kim ) 한국지방행정연구원 1993 地方行政硏究 Vol.8 No.1

슬관절전치환술 노인 환자의 원내합병증과 재원일수 영향 요인

김상미 ( Sang Mi Kim ),이현숙 ( Hyun Sook Lee ) 한국병원경영학회 2018 병원경영학회지 Vol.23 No.3

This study aims to analyze the factors affecting in-hospital complication and length of stay in elderly patients with total knee arthroplasty. A total of 8,224 inpatients over 65 years old were selected from the national old inpatient sample data which was produced by Health Insurance Review and Assessment Service in 2016. STATA 12.0 was performed using frequency, chi-square test, t-test, ANOVA and multiple linear and logistic regression analysis. Analysis results show that ages(over 85), Charlson Comorbidity Index, district(metropolitan) for general hospitals and gender, district, beds(100-199) for hospitals are significantly influenced in-hospital complication. Statistically significant factors affecting the length of stay are gender, insurance type, depression, district, bed(300 over) for general hospitals and gender, type of insurance, Charlson Comorbidity Index, depression, district, beds(200-299) for hospitals. Based on these findings, the factors affecting in-hospital complication and length of stay were different depending on the type of medical institution. Accordingly, policymakers should analyze the differences in care behavior depending on the type of medical institution and expand policy and financial support to resolve them.

제주지역 청소년의 복지태도 유형과 인권의식, 정치효능감에 관한 연구

김상미(Kim, Sang Mi) 한국지역사회복지학회 2017 한국지역사회복지학 Vol.0 No.60

본 연구의 목적은 청소년의 복지태도를 유형화하고, 인권의식과 정치효능감이 복지태도 유형화에 영향을 미치는지 분석하고자 하였다. 본 연구의 대상은 제주지역 중 · 고 · 대학생 971명으로 남자 448명(46.1%), 여자 523명(53.9%)이다. 연구 분석방법은 집단 간 T-검증과 Anova를 사용하였으며, 복지태도 유형과 영향요인간의 관계는 로지스틱 회귀분석을 실시하였다. 연구결과로서 첫째, 청소년의 복지태도는 국가의 책임정도, 복지기능의 효과성이라는 두 가지 변인으로 구성하여 4가지로 유형화 하였다. 이는 제1유형(국가책임․고효과성), 제2유형(민간의존․고효과성), 제3유형(국가책임․저효과성), 제4유형(민간의존․저효과성)으로 명명화 하였다. 둘째, 청소년의 복지태도 유형별 분포를 살펴보면, 민간의존․저효과성 37.6%, 국가책임․고효과성 31.4%, 민간의존 · 고효과성 16.3%, 국가책임․저효과성 14.7%순이었다. 셋째, 인권의식과 정치효능감이 복지태도 유형에 어떠한 영향을 미치는지 살펴본 결과, 인권의식의 세 요소 중 제2세대 권리인 경제 · 사회 · 문화적 권리를 높게 인식할수록 복지태도 유형 중 제1유형인 국가책임 · 고효과성 유형이 나타날 확률이 높게 나타났다. 정치효능감에서는 내재적 정치효능감이 높을수록 국가책임․고효과성 유형이 나타날 확률이 높게 나타났다. 연구결과를 바탕으로 논의 및 결론을 제시하였다. The purpose of this study is to categorize adolescence’s attitudes toward social welfare system and analyze how both their awareness of human rights and sense of political efficacy influence on the typology of the attitudes about social welfare. A total number of 971 students from middle schools, high schools, and colleges. The results are as follows. Firstly, the attitudes were classified into 4 types by two factors; the degrees of government’s responsibility and the efficacy of social welfare functioning. They were defined as the type 1(government responsibility & high efficacy), the type 2(private dependence & high efficacy), the type 3(government responsibility & low efficacy), and the type 4(private dependence & low efficacy). Secondly, the distributions of students’ attitudes by the types explained that 37.6% of the students responded as they preferred private dependence and low efficacy, 31.4% of them answered that they liked government responsibility and high efficacy, 16.3% of them chose private dependence and high efficacy, and 14.7% of their answers belonged to government responsibility and low efficacy. Thirdly, in the analysis of how both the awareness of human rights and the sense of political efficacy influence on the typology of their attitudes toward social welfare, the higher they estimate economic, social and cultural rights, the more likelihood they are categorized as government responsibility and high efficacy. When it comes to the sense of political efficacy, the higher their internal sense of political efficacy goes, the more likelihood the type of government responsibility and high efficacy will show. According to the results of the analysis, meaningful and significant discussions and implications are presented.

정신질환 동반 입원 환자의 치료결과와 조기합병증에 영향을 미치는 요인

김상미 ( Sang-mi Kim ),이현숙 ( Hyun-sook Lee ) 한국병원경영학회 2017 병원경영학회지 Vol.22 No.4

The purpose of the study was to investigate the patient, disease and hospital characteristics which affect treatment result and early complication for inpatients with psychiatric comorbidity. We analyzed data on 19,806 patients of the Korea Centers for Disease Control and Prevention from 2012 to 2014, Korea National Hospital discharge in-depth data. Frequency, chi-square and logistic regression analysis was performed, using STATA 12.0. According to logistic regression analysis, gender(Odds ratio(OR)=0.776, 95% confidence interval(CI)=0.686- 0.878), insurance type(OR=0.853, CI=0.731-0.995), operation(OR=0.424, CI=0.350-0.513), disposition(OR= 39.307, CI=34.394-44.923), beds(300-499, OR=0.470, CI=0.377-0.585; 500-999, OR=0.462, CI=0.395-0.541; 1000 over, OR=0.598, CI=0.480-0.745) were significant predictors of treatment result. And insurance type(OR=1.527, CI=1.241-1.879), CCI(3 over, OR=1.865, CI=1.534-2.266), operation(OR=5.399, CI=4.562- 6.389), disposition(OR=1.279, CI=1.013-1.614), district(Metropolitan city, OR=0.519, CI=0.407-0.661; Nonmetropolitan OR=0.469, CI=0.383-0.574), beds(500-999, OR=2.799, CI=1.986-3.944; 1000 over, OR=2.109, CI=1.429-3.113) were significant predictors of early complication. This research would be used as a basic data of high quality of medical care and efficient resource utilization in order to detect and minimize the negative medical treatment results of inpatients with psychiatric comorbidity.

연구논문 : 매도가능금융자산에 대한 공정가치 서열체계 정보의 가치관련성에 관한 연구

김상미 ( Sang Mi Kim ),한종수 ( Jong Soo Han ) 한국회계학회 2015 회계저널 Vol.24 No.2

본 연구는 2011회계연도부터 K-IFRS로의 전환에 따라 확대 적용되는 공정가치회계의 정보유용성을 검증하기 위하여 금융기관을 대상으로 공정가치 서열체계에 따라 분류된 매도가능금융자산의 공정가치 정보에 대한 가치관련성(value-relevance)을 실증 분석한다. K-IFRS는 공정가치를 측정하기 위하여 사용하는 가치평가기법과 관련된 투입정보를 제공하기 위하여 공정가치 서열체계를 정하였다. 동일한 자산이나 부채의 활성시장 공시가격에 가장 높은 순위(수준 1)를 부여하고 직·간접적으로 관찰 가능한 시장정보에 의해서 뒷받침 되는 투입정보는 수준 2로 분류하며 관측 가능하지 않은 투입변수에 가장 낮은 순위(수준3)를 부여하도록 하였다. 공정가치 서열체계가 낮을수록 관측 가능하지 않은 변수를 투입하여 공정가치가 측정되므로 측정오류 및 경영자의 재량으로 인한 신뢰성의 하락을 예측할수 있다. 본 연구는 이와 같은 공정가치 서열체계의 특징에 관심을 두고 이에 대한 시장의 차별적 반응에 대하여 분석하였다. 연구결과, 수준 1과 수준 2로 측정된 매도가능금융자산은 양(+)의 가치관련성을 가지는 반면, 수준 3으로 측정된 매도가능금융자산은 음(-)의 가치관련성을 가지는 것을 발견하여, 수준 3의 투입변수에 의하여 측정되는 공정가치에 대한 시장의 부정적 인식을 확인할 수 있었다. 또한 공정가치평가를 통하여 금융기관의 중요한 감독지표인 자본적정성 지표를 조정하고자 하는 유인이 있을 수 있는 바 이에 대한 시장의 반응을 검증하였다. 그 결과, 자본적정성이 낮은 금융기관의 경우, 자본적정성이 증가할수록 수준 3 투입변수로 측정된 매도가능금융자산에 대한 가치관련성은 감소하는 것으로 나타났다. 이는 자본적정성이 낮은 기업들이 수준 3으로 분류되는 매도가능금융자산을 이용하여 자본적정성 비율을 조정할 수 있는 가능성에 대하여 시장이 부정적으로 인식하고 있는 것을 시사한다. 본 연구는 공정가치 서열체계에 따라 분류된 공정가치정보에 대한 시장의 차별적 반응을 우리나라에서 처음으로 실증 분석한 연구로써 K-IFRS 도입으로 확대 적용된 공정가치평가를 시장은 항상 긍정적으로 인식하는 가에 대한 시사점을 제공한다. 또한 수준 3 투입변수에 의해 측정된 공정가치에 대한 신뢰성 확보를 위한 적절한 지침 및 제도적 보완이 필요하다는 측면에서 금융당국과 외부감사인에게 시사하는 바가 클 것으로 기대된다. The application of fair value accounting, which is one of the major characteristics of K-IFRS, keeps expanding for the purpose of providing useful information. This study empirically examines whether the fair value hierarchy information of financial institutions’ available-for-sale (AFS) financial assets is perceived to be relevant for equity valuation. The findings of this study should be important for standard setters to understand not only the effect of fair value hierarchy information disclosure, but also to enhance fair value disclosure for future standard (e.g. IFRS 9). There is a trade-off between relevance and reliability in using fair value accounting. Proponents of fair value accounting argue that it better reflects how much a firm’s assets and liabilities are worth, therefore it provides more relevant information for certain decisions. In contrast, opponents of fair value accounting argue that fair value is not as reliable as historical cost. Subjective judgement and estimation errors, which are inherent components of fair values, are difficult for investors to verify and thus, fair values could easily be used for managerial manipulation. In spite of the continuing debate on the usefulness of fair value, fair value accounting is achieving more and more popularity nowadays, especially under IFRS. IFRS 13 “Fair value measurement,” requires companies to classify financial assets and liabilities reported at fair value based on the observability of the inputs used in the measurement process; Level 1 (observed inputs from quoted prices in active markets), Level 2 (indirectly observable inputs from quoted prices of comparable items in active markets or other market.related information), and Level 3 (unobservable, firm.generated inputs). Among the three levels of fair values is the Level 3 which seems to be the most problematic. Level 3 fair values are less observable and are subject to greater information asymmetry between investors and management. Greater amount of subjectivity embedded in Level 3 fair values could include more estimation errors and be used for managerial manipulation. Therefore, Level 3 fair values, which is argued to have relevance, could have the least level of reliability. By using Ohlson‘s value relevance model (1995), this study examines the concern that fair value of the financial assets based on unobservable inputs due to lack of active markets (i.e. Level 3) is not reliable enough to be used in financial reporting. To maximize the power of test, first, this study focuses on the financial firms, because they hold large amount of financial assets and liabilities which are very sensitive to fair value accounting standard, because they have more reliable process of determining fair values than non-financial firms do, and because they have all three levels of financial assets and liabilities in their financial statements. Second, this study focuses on AFS financial assets because AFS financial assets are the largest class in the financial firms’ statement of financial position. Thus, we were able to test the value relevance of each level of the fair value hierarchy information under same accounting treatment. First, we test the value relevance of each level of the fair value hierarchy information. We expect that information asymmetry between investors and managers can cause more serious problems as fair value inputs become more unobservable by investors. We find that the coefficient of Level 3 AFS financial assets are consistently lower than that of Level 1 or Level 2 AFS financial assets. We also find that the coefficient of Level 3 AFS financial assets is negative. Collectively, the evidence suggests that equity investors recognize Level 3 information unreliable because of its intrinsic measurement error and the error caused by information asymmetry between managers and investors. Second, we examine whether value relevance of the fair value hierarchy information depends on firms’ capital adequacy ratio. The capital adequacy ratio is an important concern for the management and investors of financial firm. Therefore, the management of financial firms have incentives to use their discretion on the estimation of Level 3 fair values to manage the reported level of regulatory capital adequacy ratio. We find that the value relevance of Level 3 AFS financial assets deteriorates as the capital adequacy ratio increases for the firms who have lower capital adequacy ratio. This result suggests that equity investors suspect the earnings management through Level 3 financial assets especially for the firms who have lower capital adequacy ratio. We believe that this paper, by demonstrating the value relevance of fair value hierarchy information for the first time in Korea, can contribute to extant the insight regarding the usefulness of fair value accounting. And our results suggest that regulators and external auditors should develop adequate guidance and systematic complement to reserve reliability of fair value information.