• Title/Summary/Keyword: 부채유형

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Key Bit-dependent Attack on Side-Channel Analysis-Resistant Hardware Binary Scalar Multiplication Algorithm using a Single-Trace (부채널 분석에 안전한 하드웨어 이진 스칼라 곱셈 알고리즘에 대한 단일 파형 비밀 키 비트 종속 공격)

  • Sim, Bo-Yeon;Kang, Junki;Han, Dong-Guk
    • Journal of the Korea Institute of Information Security & Cryptology
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    • v.28 no.5
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    • pp.1079-1087
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    • 2018
  • Binary scalar multiplication which is the main operation of elliptic curve cryptography is vulnerable to the side-channel analysis. Especially, it is vulnerable to the side-channel analysis which uses power consumption and electromagnetic emission patterns. Thus, various countermeasures have been studied. However, they have focused on eliminating patterns of data dependent branches, statistical characteristic according to intermediate values, or the interrelationships between data. No countermeasure have been taken into account for the secure design of the key bit check phase, although the secret scalar bits are directly loaded during that phase. Therefore, in this paper, we demonstrate that we can extract secret scalar bits with 100% success rate using a single power or a single electromagnetic trace by performing key bit-dependent attack on hardware implementation of binary scalar multiplication algorithm. Experiments are focused on the $Montgomery-L{\acute{o}}pez-Dahab$ ladder algorithm protected by scalar randomization. Our attack does not require sophisticated pre-processing and can defeat existing countermeasures using a single-trace. As a result, we propose a countermeasure and suggest that it should be applied.

Syngeographical Characteristics of Forest Vegetation in Limestone Areas, Mt. Deokhang, Kangwondo (강원도 덕항산 석회암지대 산림식생의 군락지리 특성)

  • Bae, Kwan-Ho;Kim, Jun-Soo;Cho, Hyun-Je;Yun, Chung-Weon;Cho, Yong-Chan
    • Korean Journal of Environment and Ecology
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    • v.28 no.2
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    • pp.161-170
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    • 2014
  • This study classified the types of major forest vegetation and analyzed the syngeographical characteristics of the vegetation in the Mt. Deokhang with exhumed lime rocks. The forest vegetation on the ridge of Mt. Deokhang was classified into 1 community group, 3 communities, 2 groups, and 2 subgroups, 5 types in total. The syngeographical form of Deokhangsan fully exhibited the topographical peculiarity, proximity to subalpine, and limestone zone. In addition, Carex ciliato-marginata, Carex humilis var. nana, and so forth which appear as species with high consistency in the well-drained semiarid zone represent the soil environment of the lime stone area and northern plants such as Carex ussuriensis and Asplenium ruta-muraria represent the characteristics of the vegetation in alpestrine in close proximity. Moreover, the Carpinus turczaninowii in the area appears to show the characteristics of migratory vegetation due to the peculiarity of the habitat. The syngeographical characteristics of this study area show both the characteristics of the habitat and phytogeographic characteristics. Furthermore, they are expected to contribute to the diversity in community and habitat form in Korean peninsula in terms of vegetation science.

A Comparison of Household Characteristics by Deficit Types (적자가계유형분류에 따른 가계특성 변화 분석)

  • Yang, Sejeong;Lee, Eunhwa;Lee, Jonghee
    • Journal of Families and Better Life
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    • v.33 no.1
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    • pp.19-39
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    • 2015
  • The purpose of the study was to examine the characteristics and economic status of deficit households. The data for this study were from The Household Income and Expenditure Survey in 2000, 2005, and 2010 conducted by the National Statistics Office (NSO). Deficit households were defined by those who had expenditures higher than their income. Among total households, the proportion of deficit households was 26.84% in 2000, 28.14% in 2005, and 27.15% in 2010. The average propensity to consume was 132.1 in 2005, which was higher than those in 2000 and 2010. Deficit households were classified into five types using cluster analysis: 1)overall-overconsumption group(33.07%), 2)basic needs group(26.33%), 3)transportation expenditure-dominated group(6.73%), 4)education expenditure-dominated group(27.63%), 5)health care expenditure-dominated group(6.24%). The overall-overconsumption group was the largest group of total households and the portion of this group among total households decreased by 4.97%p from 2005 to 2010. However, the education expenditure-dominated group increased by approximately 7.6%p over the period. It was also found that households in 2000 and 2010 were more likely to be in all five groups than households in 2005. Other major determinants of households with deficit were gender, age, number of family members, education level, dual income, home ownership, vehicle ownership, and income class.

An Analysis on the Household Characteristics and Economic Status of Deficit Households (적자가계의 특성 및 경제구조 분석)

  • Yang, Se-Jeong
    • Journal of Family Resource Management and Policy Review
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    • v.14 no.1
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    • pp.135-159
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    • 2010
  • The purpose of the study was to investigate the characteristics and economic status of deficit households compared to surplus households. Data from The Household Income and Expenditure Survey 2005 by NSO and 50, 207 salary/wage earners' households were used for the analysis. The statistical methods used were GLM, logit, and cluster analyses. The analysis results showed that 25.3 percent of the households were deficit households. Approximately half of the lowest 20% income group were deficit households. Income deficit households earned 1, 273 thousand less than that of surplus households, whereas consumption of deficit households was 1, 006 thousand more than that of surplus households. The average propensity of consumption of deficit households was 142.1. According to the logit analysis, factors contributing to the probability of belonging to a deficit household included income level, household size, age and educational level, occupation, homeownership, car ownership, and wife's employment status. Deficit households were classified into 5 types: 1) health care expenditure-dominated group, 2) housing expenditure-dominated group, 3) education expenditure-dominated group, 4) money transfer-dominated group, and 5) overall-overconsumption group. The overall-overconsumption group was the largest group of all at 58.5%. It was found that for all five groups, the changes in household size, income group, home ownership, and occupation of the individual were variables that influenced the probability of belonging to a certain group.

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Monetary Policy in a Two-Agent Economy with Debt-Constrained Households (가계부채 제약하의 통화정책: 2주체 거시모형(TANK)에서의 정량적 분석)

  • Jung, Yongseung;Song, SungJu
    • Economic Analysis
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    • v.25 no.2
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    • pp.1-53
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    • 2019
  • This paper examines monetary policy quantitatively in a two-agent and small-scale New-Keynesian economy with debt-constrained households that cannot smooth their consumption intertemporally and frictionlessly since highly indebted households are not allowed to borrow above a certain debt ceiling in incomplete financial markets without additional risk premiums due to information asymmetry between savers and borrowers. We find that, in the event of cost shocks, the asymmetric responses of borrowing households without, and saving households with, dividend incomes lead to different labor supplies and consumptions over heterogeneous households, and eventually to an extension of the monetary policy transmission channels. The income effect and low elasticity of the labor supply play key roles in such asymmetric responses over heterogeneous households. We also find that the social welfare in a flexible inflation targeting (FIT) monetary policy, in which both the inflation gap and the output gap are considered in an integrated manner when policy-making, is similar to that of the Ramsey optimal monetary policy (ROP), in which the shares of debt-constrained households, as well as all economic states, including both the inflation gap and output gap, are considered comprehensively for policy-making, and that it is greater than that of simple inflation targeting (SIT) monetary policy, in which only the inflation gap is considered mechanically for policy-making. Such social welfare implies that a FIT policy may still work even in an economy with a sizable number of debt-constrained households. Further, the responses of cost shocks to consumption and labor supply are dying out more slowly under FIT and ROP policies than under an SIT policy.

Householder's Working Type and Household Saving: A Perspective of the Precautionary Saving Behavior Theory (가구주 근로유형과 가계저축: 예비적 저축행동 이론의 관점)

  • Shim, Young
    • Journal of Consumption Culture
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    • v.15 no.1
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    • pp.93-118
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    • 2012
  • The purpose of this study was to examine the effect of a householder's working type on household saving from the perspective of precautionary saving behavior theory and the determinants of household saving by householder's working type. The data for this study was from the 2009 year of the Korea Welfare Panel Survey (KOWEPS), consisting of 2,463 households with householders whose working type was regular or non-regular employment(temporary, daily or public work). OLS regression analyses and Chow-tests were performed. In the regression analyses, the dependent variables for household saving were precautionary saving and precautionary asset. Precautionary saving was operationalized with the amount of average monthly saving and the ratio of average monthly saving to average monthly disposable income, and precautionary asset was operationalized with the amount of financial assets and the ratio of financial assets to net assets. The independent variables were household income, household assets, householder's working type(regular, non-regular), householder's age, sex, education level and marriage status, income level, the number of household members, housing type, debt, and public transfer income. Monthly average total consumption expenditures for household income, and net assets for household assets, the existence of spouse for marriage status, poverty for income level were used. Public transfer income was classified into three, social insurance, basic assistance and government assistance. For the analyses, Stata 11.0 version was used. The results are as follows: Householder's working type was significantly related to the precautionary saving behavior of a household. However, the precautionary saving and the precautionary asset of a household with a householder in non-regular working type was lower than those of a household with a householder in regular working type. This result is not consistent with the expectation from the perspective of precautionary saving behavior that the saving of a household with a householder in non-regular working type is expected to be higher than that of a household with a householder in regular working type. According to the analyses of the determinants for precautionary saving behavior by householder's working type, monthly average total consumption expenditures, debt, net assets, poverty, the number of household members, basic assistance were statistically significant variables. The positive relation of basic assistance to precautionary saving(the amount of average monthly saving and the ratio of average monthly saving)is a noteworthy result in the analyses of the determinants for household saving by householder's working type. The above results suggest the followings. First, it is easy to predict the unstability of economic life of a household with a householder in non-regular working type because of relatively low precautionary saving and precautionary asset. The reason for the low precautionary saving and the low precautionary asset may be a low current income of the household in spite of its willingness to save. If this reasoning is possible, it suggests that policies are needed for households with householders in non-regular working type to save. Second, the relatively low precautionary saving and precautionary asset of a household with a householder in non-regular working type suggest also their long-term economic stability. This suggests they need to try a long-term financial planning even though they have limitations to save for future because of their low current income. It is necessary to develop the financial planning for the households with unstable incomes. Third, the determinants for precautionary saving behavior by householder's working type were mostly the ones which reflect the economic condition of a household. This suggests that the economic condition of a household is a core factor for household saving. Consequently, it emphasizes the efforts for a household to acquire the adequate level of income for saving. Forth, the positive relation of basic assistance to precautionary saving(the amount of average monthly saving and the ratio of average monthly saving) suggests the possibility for a household to accumulate the precautionary saving and the precautionary asset in the channel of basic assistance.

The Pattern Analysis of Financial Distress for Non-audited Firms using Data Mining (데이터마이닝 기법을 활용한 비외감기업의 부실화 유형 분석)

  • Lee, Su Hyun;Park, Jung Min;Lee, Hyoung Yong
    • Journal of Intelligence and Information Systems
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    • v.21 no.4
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    • pp.111-131
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    • 2015
  • There are only a handful number of research conducted on pattern analysis of corporate distress as compared with research for bankruptcy prediction. The few that exists mainly focus on audited firms because financial data collection is easier for these firms. But in reality, corporate financial distress is a far more common and critical phenomenon for non-audited firms which are mainly comprised of small and medium sized firms. The purpose of this paper is to classify non-audited firms under distress according to their financial ratio using data mining; Self-Organizing Map (SOM). SOM is a type of artificial neural network that is trained using unsupervised learning to produce a lower dimensional discretized representation of the input space of the training samples, called a map. SOM is different from other artificial neural networks as it applies competitive learning as opposed to error-correction learning such as backpropagation with gradient descent, and in the sense that it uses a neighborhood function to preserve the topological properties of the input space. It is one of the popular and successful clustering algorithm. In this study, we classify types of financial distress firms, specially, non-audited firms. In the empirical test, we collect 10 financial ratios of 100 non-audited firms under distress in 2004 for the previous two years (2002 and 2003). Using these financial ratios and the SOM algorithm, five distinct patterns were distinguished. In pattern 1, financial distress was very serious in almost all financial ratios. 12% of the firms are included in these patterns. In pattern 2, financial distress was weak in almost financial ratios. 14% of the firms are included in pattern 2. In pattern 3, growth ratio was the worst among all patterns. It is speculated that the firms of this pattern may be under distress due to severe competition in their industries. Approximately 30% of the firms fell into this group. In pattern 4, the growth ratio was higher than any other pattern but the cash ratio and profitability ratio were not at the level of the growth ratio. It is concluded that the firms of this pattern were under distress in pursuit of expanding their business. About 25% of the firms were in this pattern. Last, pattern 5 encompassed very solvent firms. Perhaps firms of this pattern were distressed due to a bad short-term strategic decision or due to problems with the enterpriser of the firms. Approximately 18% of the firms were under this pattern. This study has the academic and empirical contribution. In the perspectives of the academic contribution, non-audited companies that tend to be easily bankrupt and have the unstructured or easily manipulated financial data are classified by the data mining technology (Self-Organizing Map) rather than big sized audited firms that have the well prepared and reliable financial data. In the perspectives of the empirical one, even though the financial data of the non-audited firms are conducted to analyze, it is useful for find out the first order symptom of financial distress, which makes us to forecast the prediction of bankruptcy of the firms and to manage the early warning and alert signal. These are the academic and empirical contribution of this study. The limitation of this research is to analyze only 100 corporates due to the difficulty of collecting the financial data of the non-audited firms, which make us to be hard to proceed to the analysis by the category or size difference. Also, non-financial qualitative data is crucial for the analysis of bankruptcy. Thus, the non-financial qualitative factor is taken into account for the next study. This study sheds some light on the non-audited small and medium sized firms' distress prediction in the future.

Performance of OFDM M-ary QAM System in the presence of Carrier Frequency Offset (반송파 주파수 옵셋에 따른 OFDM M-ary QAM 시스템의 성능 분석)

  • 계선형;유형석;서종수
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.24 no.6B
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    • pp.1024-1031
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    • 1999
  • In order to transmit high-speed wide band signals efficiently in multipath fading environments, M-ary QAM signalling combined with OFDM transmission technique is applied. In this paper, the effect of synchronization error caused by carrier frequency offset and SER(Symbol Error Rate) performance of OFDM-16QAM and OFDM-64QAM are theoretically analyzed. Our result shows that as the number of sub-carrier in OFDM system increases the frequency-offset caused inter-channel interference(ICI) increases significantly, and that an error floor occurs even at high SNR of OFDM system. For OFDM-64QAM, the error floor occurs at SER=1$\times$10-7 when a normalized frequency-offset is 0.001, in which the SNR degradation is much greater than that of OFDM-16QAM. From this study the maximum allowable frequency-offset of OFDM-16QAM and OFDM-64QAM systems can be determined to meet the specific SER requirement.

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The Flora of Protected Area for Forest Genetic Resource Conservation in the Mt. Cheongok (청옥산 산림유전자원보호구역의 관속식물상)

  • Byun, Jun-Gi;Shin, Jae-Kwon;Kim, Ju-Yeong;Choi, Seung-ho;Kim, Dong-Kap
    • Proceedings of the Plant Resources Society of Korea Conference
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    • 2018.04a
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    • pp.46-46
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    • 2018
  • 본 연구는 봉화군 청옥산 산림유전자원보호구역에 분포하는 관속식물을 파악하고자 수행하였다. 청옥산 보호구역은 산림청에서 '희귀식물자생지' 유형으로 지정하여 관리하고 있으며, 면적은 약 2,051ha에 달하며 주로 신갈나무군락과 소나무군락이 우점하고있다. 현지조사는 2017년 3월부터 10월까지 계절별로 수행하였다. 조사결과, 보호구역내 관속식물은 86과 258속 390종 4아종 54변종 6품종으로 총 454분류군의 분포가 확인되었다. 이 중 한국특산식물은 가야물봉선, 처녀치마, 할미밀망, 키버들 등 11분류군이며, 산림청 지정 희귀식물은 취약종(VU)에 주목, 백작약, 꼬리진달래 3분류군, 약관심종(LC)에 등칡, 도깨비부채, 정향나무, 말나리, 나도개감채 등 14분류군이다. 식물구계학적 특정식물로는 IV등급인 회리바람꽃, 가지괭이눈, 산겨릅나무, 귀박쥐나물 등 10분류군, III등급인 애기감둥사초, 중나리, 토현삼, 선갈퀴, 금강제비꽃, 노랑갈퀴, 분비나무 등 23분류군, II등급 32분류군, I등급 30분류군이 확인되었다. 외래식물은 오리새, 털별꽃아재비, 왕포아풀, 주걱개망초, 지느러미엉겅퀴, 족제비싸리 등 18분류군이 임도 주변에서 확인되었다. 조사된 관속식물을 용도별로 구분하면 식용식물 181분류군, 섬유용식물 6분류군, 약용식물 143분류군, 관상용식물 52분류군, 사료용식물 172분류군, 염료용식물 9분류군, 목재용식물 22분류군으로 분석되었다.

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The Impact of Economic Hardship on Domestic Violence among Low-Income Korean Households: Investigating the Moderation Effect of Debts (저소득층의 경제적 어려움과 가정폭력: 유형별 부채사용의 조절효과를 중심으로)

  • Son, Jiyeon;Park, Jooyung
    • The Korean Journal of Community Living Science
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    • v.28 no.4
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    • pp.599-611
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    • 2017
  • The purpose of this study is to investigate the effect of increased debt on the incidence of domestic violence over the two-year interval 2014-2016. To investigate Korean low-income households with economic hardships, we analyzed the 9th and the 11th waves of the Korea Welfare Panel Study, which is jointly sponsored by the Korea Institute for Health and Social Affairs and the Institute of Social welfare, Seoul National University. The study analysis was based on data from 2,786 households with less than 60% of median income. The main study findings are as follows. First, increases in economic hardships incur domestic violence for low-income households, while increases in low-interest debt decrease the incidence of the domestic violence when controlling for economic hardships. All other things being equal, economic hardship works as a stressor and low-interest debt works as an alleviator influencing domestic violence. Second, when low-income households are experiencing economic hardships, low-interest debt fails to work as an alleviator. Under this circumstance, high-interest debt actually acts as a stressor influencing domestic violence. Thus, we can speculate that use of debt under economic hardships will occur domestic violence for low-income households. This study differs from previous studies in that it examines the effect of increase in debt on the incidence of the domestic violence across different types of debt: low interest, high interest, and credit card. We can conclude that debt can function as a stressor or an alleviator for low-income households, depending on the interest rate and the households' financial situation.