소음성 난청자의 순음청력역치와 어음청취역치 및 청성뇌간반응 역치와의 비교

김규상 한국청각언어재활학회 2009 Audiology and Speech Research Vol.5 No.1

Pure-tone thresholds (PTTs), speech reception threshold (SRT), and auditory brainstem response (ABR) threshold were compared in 100 ears with noise-induced hearing loss to examine the accuracy of prediction for hearing thresholds. The 100 subject ears, which were with sensorineural hearing loss and no history of ear disease, were selected from 62 male workers who were exposed to noise in automobile manufacturing factory and suspected of noise-induced hearing loss. PTTs were determined using modified ascending method in 5-dB steps by pure tone audiometry (PTA);threshold for speech were measured as SRT;and ABR threshols was defined as the lowest stimulus intensity at which V wave could be clearly observed. SRT was lower than the average PTTs, and ABR threshold was higher than PTTs and SRT. Simple regression analysis was carried out to examine the relationship between SRT and the average PTTs and thresholds by frequency by PTA. PTTs in low frequency region (0.5-1 kHz) showed higher association, with explanatory power of more than 70%, and particularly the average PTTs by three division method showed the highest association with SRT. Simple regression analysis for the relationship between ABR threshold and the average PTTs and thresholds by frequency by PTA revealed that PTTs in 2-6 kHz region was more highly associated with ABR threshold.

Optimal Attenuation Threshold for Quantifying CT Pulmonary Vascular Volume Ratio

Goo Hyun Woo,Park Sang-Hyub 대한영상의학회 2020 Korean Journal of Radiology Vol.21 No.6

Objective: To evaluate the effects of attenuation threshold on CT pulmonary vascular volume ratios in children and young adults with congenital heart disease, and to suggest an optimal attenuation threshold. Materials and Methods: CT percentages of right pulmonary vascular volume were compared and correlated with percentages calculated from nuclear medicine right lung perfusion in 52 patients with congenital heart disease. The selected patients had undergone electrocardiography-synchronized cardiothoracic CT and lung perfusion scintigraphy within a 1-year interval, but not interim surgical or transcatheter intervention. The percentages of CT right pulmonary vascular volumes were calculated with fixed (80–600 Hounsfield units [HU]) and adaptive thresholds (average pulmonary artery enhancement [PAavg] divided by 2.50, 2.00, 1.75, 1.63, 1.50, and 1.25). The optimal threshold exhibited the smallest mean difference, the lowest p-value in statistically significant paired comparisons, and the highest Pearson correlation coefficient. Results: The PAavg value was 529.5 ± 164.8 HU (range, 250.1–956.6 HU). Results showed that fixed thresholds in the range of 320–400 HU, and adaptive thresholds of PAavg/1.75–1.50 were optimal for quantifying CT pulmonary vascular volume ratios. The optimal thresholds demonstrated a small mean difference of ≤ 5%, no significant difference (> 0.2 for fixed thresholds, and > 0.5 for adaptive thresholds), and a high correlation coefficient (0.93 for fixed thresholds, and 0.91 for adaptive thresholds). Conclusion: The optimal fixed and adaptive thresholds for quantifying CT pulmonary vascular volume ratios appeared equally useful. However, when considering a wide range of PAavg, application of optimal adaptive thresholds may be more suitable than fixed thresholds in actual clinical practice.

클릭유발 청성뇌간반응과 순음청력검사의 평균 및 주파수에 따른 상관관계 분석

서재현,전은주,박용수,김주은,김동현,남인철,이일환,이호석 대한이비인후과학회 2012 대한이비인후과학회지 두경부외과학 Vol.55 No.12

Background and Objectives The aim of this study is to assess the correlation between the threshold of click-evoked auditory brainstem response (ABR) and the pure-tone averages in various formulas. Subjects and Method Data were obtained from 207 patients (326 ears) with sudden sensorineural hearing loss. All subjects underwent hearing threshold evaluation using pure tone audiogram (PTA), speech audiogram and click-evoked ABR. Linear regression analyses were applied to assess the relation between threshold of click-evoked ABR and threshold of separate frequencies of the PTA and to analyze the correlation between threshold for click-evoked ABR and various pure-tone averages. Results Results revealed a significant relation between the threshold of click-evoked ABR and PTA thresholds at 0.5 kHz, 1 kHz, 2 kHz, 3 kHz, and 4 kHz. The highest coefficients of regression and determination were 1.026 for 4 kHz and R2=0.663 for 3 kHz, respectively. The coefficient of regression was highest (=0.995) for the mean of PTA thresholds for 3 kHz and 4 kHz. The coefficient of determination was highest for the mean of PTA thresholds for 1, 2, 3 and 4 kHz (R2=0.732). Multiple regression analysis showed a significant relation between the ABR threshold and PTA thresholds for 1, 3, and 4 kHz (R2=0.732), with highest correlation coefficient at 3 kHz [ABR=11.79+(0.17×1 kHz)+(0.26×3 kHz)+(0.23×4 kHz), (p<0.05)]. Conclusion The threshold of click-evoked ABR correlates best with the mean of PTA thresholds for 1, 2, 3 and 4 kHz. The PTA threshold for 3 kHz has highest correlation with the ABR threshold. Korean J Otorhinolaryngol-Head Neck Surg 2012;55:764-70

Empirically Based Rainfall Threshold for Landslides Occurrence in Peninsular Malaysia

Abdul Muaz Abu Mansor Maturidi,Norhidayu Kasim,Kamarudin Abu Taib,Wan Nur Aifa Wan Azahar,Husna Binti Ahmad Tajuddin 대한토목학회 2021 KSCE JOURNAL OF CIVIL ENGINEERING Vol.25 No.12

Empirical rainfall thresholds for the purpose of shallow landslide forecasting are proposed for Peninsular Malaysia where numerous slope failures are reported due to the intense rainfall in conjunction with the humid tropical climate. Thirty-seven cases of landslide-triggering-rainfall were selected from 1993 to 2018 to identify the correlation between rainfall and shallow landslide through the analysis of specific rainfall events. The derived rainfall parameters were applied to establish two rainfall thresholds of (Imean-D) and (Imax-D) via practical methods. For the identical range of event duration 1 < D < 263 h, the (Imean-D) threshold formula was expressed as I = 17.5 D−0.722, while the (Imax-D) threshold was defined as I = 37.8 D−0.114. Both thresholds performed different functionalities with a primary goal of predicting shallow landslides. When both (Imean-D) and (Imax-D) thresholds were compared with the thresholds proposed by various studies worldwide, both dominated the upper positions. More rainfall is required for land sliding due to the high thickness of the Malaysian soil that is associated with the abundant tropical downpour. From the perspective of the antecedent, the period of prolonged precipitation or short heavy rainfall from 1 to 10 days can result in shallow landslides for Peninsular Malaysia. In the context of geology, the igneous rock type of granite has the highest susceptibility to the shallow landslide at 65%, despite other rock types of sedimentary and metamorphic. The threshold validation depicted all True Positive events for the (Imax-D) threshold, and one Negative False event for the (Imean-D) threshold. The (Imean-D) threshold was revised to acquire the new value, but it needed to deal with the possibility of False Alarm and the (Imax-D) threshold seemed to be more credible to represent the rainfall-induced shallow landslide threshold for Peninsular Malaysia.

신규상장기업의 임계이익충족

심호석 한국공인회계사회 2018 회계·세무와 감사 연구 Vol.60 No.4

We study on beating earnings thresholds of initially public offering firms(hereafter IPOs). Specifically, we empirically test how frequently IPOs beat earnings thresholds and how largely they manage earnings upward in comparison to those of already listed firms. To be successfully listed, IPOs need to be seen as prospective to grow to investors. Prior studies have reported that IPOs have incentives to manage earnings upward during the periods of listing. Therefore, we study on how frequently and largely IPOs conduct earnings management to beat earnings thresholds in the face of initial public offering, a very important event to their growth. We classify earnings management into six types to test the frequency of beating earnings thresholds and size of earnings management, based on the location of pre-managed and post-managed earnings and the direction of management(upward or downward) on the earnings distributions. We focus on type Ⅱ that pre-managed earnings are below earnings thresholds but post-managed earnings are above those. Those firms are considered as managing earnings upward to beat earnings thresholds. We see earnings managements of IPOs compared to those of already listed firms that belong to type Ⅱ. The initial public offering periods are defined as during the six years from 3 years before to 2 years after listing. Already listed periods are since three years after listing. Our hypotheses are that the frequency of beating earnings thresholds or the size of earnings management of IPOs would be bigger than those of already listed firms. Samples are initially listed firms from 2001 to 2016 in KOSPI or KOSDAQ market. The results of analyses with samples whose pre-managed earnings are below earnings thresholds show that IPOs beat earnings thresholds more frequently and manage earnings upward larger than those of already listed firms. These results are not changed irrespective of before or after listing and in the K-GAAP or K-IFRS periods, even including samples that fail to listing. We conduct additional analyses considering the earnings amount determined by the listing institute as another threshold. The result shows that 48% of IPOs beat the threshold. Even though 52% of IPOs did not beat it, they were successful to be listed. This lead us to a conclusion that the earnings amount determined by the listing Institute are always not the absolute hurdle to achieve to be listed. One of the reasons is that the listing Institute provides several options to achieve to be listed, which is due to the policy of the listing Institute trying to list IPOs that are probable to grow in the future rather than in the present. This study seems meaningful in that we extend threshold study to the initial public offering situations. Listing could be a turning point of firm's growth. Faced with newly listing, managers have incentives to deliver a good prospect to market through beating earnings thresholds. They could manipulate earnings upward, doing harms to investors to take private benefits. Therefore, the listing Institute needs to recognize IPOs beating earnings thresholds through upward earnings management and keep an eye on their movement after listing. This study could provide us an implication on IPO systems. The earnings benchmark determined by the listing Institute should be adjusted appropriate to the realities. 본 논문은 신규상장기업의 임계이익충족(beating earnings thresholds)에 관해서 실증적으로 연구한다. 구체적으로 신규상장기업이 이익의 상향조정을 통해 임계이익을 충족하는 빈도가 얼마나 높은지, 임계이익충족을 위해 얼마나 이익을 조정하는지를 기존상장기업의 임계이익충족과 비교를 통해 검증한다. 상장에 성공하기 위해 그리고 상장기업으로 안착하기 위해 신규상장기업은 투자자들에게 밝은 전망을 보여주어야 할 것이다. 선행연구들은 상장 이전이나 이후에 신규상장기업이 이익을 상향조정할 동기를 갖는 것으로 보고한다. 따라서 본 연구는 기업공개라는 일대의 사건에 직면하여 신규상장기업이 임계이익을 충족하기 위하여 얼마나 이익을 조정하는지 검증한다. 본 연구는 신규상장기업의 임계이익 충족빈도와 이익조정규모를 검증하기 위하여 임계이익분포 상에서 조정전이익과 조정후 보고이익의 위치, 그리고 이익조정방향(상향조정 및 하향조정)을 기준으로 이익조정유형을 6가지로 분류한다. 그 중 조정전이익이 임계이익을 밑도는데 조정후이익이 임계이익을 넘어서는 이익조정유형(유형Ⅱ)에 집중한다. 이러한 이익조정유형을 보이는 표본들은 임계이익을 충족할 목적으로 이익을 상향조정한 것으로 볼 수 있다. 본 연구는 유형Ⅱ에 속하는 신규상장표본의 빈도와 이익조정규모를 기존상장표본을 벤치마크로 삼아 비교한다. 분석결과, 신규상장기업은 동일한 조건의 기존상장기업에 비해 적자를 회피하거나 전년도이익을 초과하는 빈도가 상대적으로 높고, 임계이익 충족목적의 이익조정규모가 큰 것으로 나타났다. 이러한 결과는 상장이전이나 이후에도 동일하였고, KGAAP시기와 KIFRS시기로 구분하여 분석해 보아도 마찬가지였다. 상장심사에서 탈락한 기업을 포함하여 분석해 보아도 결과는 변하지 않았다. 추가적으로 상장심사요건을 임계이익으로 설정하고, 상장예정기업이 상장심사요건을 충족하는 빈도를 검증하였다. 검증 결과 이익기준 상장요건이 반드시 충족해야 할 임계이익은 아니라는 결론에 이르렀다. 그 이유는 상장심사당국이 여러 가지 성과기준을 마련해 놓고 그 중 하나만 충족하면 상장이 될 수 있는 길을 열어 놓았기 때문이다. 그것은 상장신청 당시의 성과보다는 미래의 성장성이 높은 기업을 상장시키려는 상장심사당국의 정책적인 고려 때문이었다. 본 연구는 상장심사요건인 이익기준을 보다 현실화해야 한다는 시사점을 제공할 수 있을 것이다.

반복경두부자기자극에 의한 전류인지역치 및 통증내성역치의 변화

손민균,조강희,지성주,이태성 대한재활의학회 2008 Annals of Rehabilitation Medicine Vol.32 No.5

Objective: To investigate the effect of high-frequency repetitive transcranial magnetic stimulation (rTMS) over the primary motor cortex on sensory and pain perception. Method: We measured the current perception threshold and the pain tolerance threshold with NeurometerⓇ CPT/C in 14 healthy subjects (eleven males and three females, mean age: 25.0 years). Threshold testing was evaluated prior to, immediately after, 30 min after and 60 min after rTMS. The stimulation parameters were a frequency of 10 Hz and a field intensity of 100% of the active motor thresholds. Stimuli were provided in trains of 100 pulses, followed by a 50s rest period, 10 trains were applied in the session, resulting in 1,000 pulses in total. Results: The current perception thresholds of 5, 250, 2,000 Hz were significantly increased immediately, 30 min after rTMS (p<0.05) and no effects at all were noticed after sham rTMS. The pain tolerance thresholds of 5, 250 Hz were significantly increased immediately, 30 min after rTMS and the pain tolerance threshold of 2,000 Hz were significantly increased immediately, 30 min, 60 min after rTMS (p< 0.05). No effects at all were noticed after sham rTMS. Conclusion: After high frequency rTMS over the primary motor cortex, we found that the current perception thresholds and the pain tolerance thresholds of 5, 250, 2,000 Hz were significantly increased. Objective: To investigate the effect of high-frequency repetitive transcranial magnetic stimulation (rTMS) over the primary motor cortex on sensory and pain perception. Method: We measured the current perception threshold and the pain tolerance threshold with NeurometerⓇ CPT/C in 14 healthy subjects (eleven males and three females, mean age: 25.0 years). Threshold testing was evaluated prior to, immediately after, 30 min after and 60 min after rTMS. The stimulation parameters were a frequency of 10 Hz and a field intensity of 100% of the active motor thresholds. Stimuli were provided in trains of 100 pulses, followed by a 50s rest period, 10 trains were applied in the session, resulting in 1,000 pulses in total. Results: The current perception thresholds of 5, 250, 2,000 Hz were significantly increased immediately, 30 min after rTMS (p<0.05) and no effects at all were noticed after sham rTMS. The pain tolerance thresholds of 5, 250 Hz were significantly increased immediately, 30 min after rTMS and the pain tolerance threshold of 2,000 Hz were significantly increased immediately, 30 min, 60 min after rTMS (p< 0.05). No effects at all were noticed after sham rTMS. Conclusion: After high frequency rTMS over the primary motor cortex, we found that the current perception thresholds and the pain tolerance thresholds of 5, 250, 2,000 Hz were significantly increased.

강원도 춘천 지역의 산사태 발생 강우 임계치 분석

이원영(Won Young, Lee),성효현(Hyo Hyun, Sung) 대한지리학회 2018 대한지리학회지 Vol.53 No.5

본 연구의 목적은 강원도 춘천 지역에서 산사태를 일으키는 강우강도와 지속시간의 임계치와 누적강우량과 지속시간의 임계치를 구하고, 그에 대한 검증을 통해 최적 임계치를 구하는 것이다. 이를 위해 강우 이벤트의 정의를 주관적 정의, 24시간 무강수 기간 기준의 총 누적강우량을 반영한 강우 이벤트 정의, 24시간 무강수 기간 기준의 시간최대강우량 발생시점까지의 누적강우량을 반영한 강우 이벤트 정의의 3가지로 나누고, 분위회귀분석 방법으로 춘천 지역의 산사태 발생에 대한 2퍼센타일과 10퍼센타일의 임계치 식을 구하였다. 임계치에 대한 검증을 위해 Contingency Table과 Skill Score 값을 분석한 결과, 24시간 무강수 기간의 총 누적강우량에 대한 누적강우량과 지속시간의 2퍼센타일 임계치(E=73.915D<SUP>0.2046</SUP>, 22≤D≤231)가 최적의 임계치로 도출되었다. 그 다음으로 동일한 강우 이벤트 정의에서 구한 강우강도와 지속시간의 2퍼센타일 임계치(I=75.423D<SUP>-0.798</SUP>, 22≤D ≤231)가 2번째로 최적인 임계치로 도출되었다. 따라서 로컬 스케일의 강우 임계치 연구에서 누적강우량과 지속시간의 임계치가 강우강도와 지속시간의 임계치보다 산사태의 발생 가능성에 대한 예측 정확성을 높이고, 산사태 오경보 가능성을 최소화할 수 있는 최적의 판별 조건임을 알 수 있었다. 이는 산사태 발생여부 및 산사태 발생지점수와 강우요소와의 상관분석 결과에서 누적강우량과의 상관계수가 가장 높고, 강우강도와의 상관계수가 가장 낮은 것에서도 누적강우량의 중요성을 보여준다. 또한 산사태 발생유무는 강우지속시간보다 시간최대강우량과의 상관성이 더 높았고, 산사태 발생지점수는 시간최대강우량보다 강우지속시간과의 상관성이 높았다. 춘천지역의 강우 임계치를 대한민국 전역의 임계치와 비교하면 전반적으로 보다 긴 강우지속시간, 더 많은 누적강우량에서 산사태가 발생하기 시작하였다. The objective of this study is to determine intensity-duration thresholds and cumulative rainfall-duration thresholds for triggering landslides in Chuncheon, Korea, and to find the optimal threshold value through verification. For the purpose, we defined the definition of rainfall event as the subjective definition, total cumulative rainfall event after over 24-hour non-rainfall period, and cumulative rainfall until the hourly maximum rainfall after over 24-hour non-rainfall period. And 2 percentile and 10 percentile rainfall thresholds in chuncheon region were established, using quantile regression analysis. As a result of the analysis of the Contingency Table and the Skill Score value for the validation of the threshold value, cumulative rainfall-duration thresholds that reflect total cumulative event rainfall after over 24-hour non-rainfall period (E=73.915D<SUP>0.2046</SUP>, 22≤D≤231) was derived as the most optimal threshold value. Next, the rainfall intensity-duration threshold (I=75.423D<SUP>-0.798</SUP>, 22≤D≤231) obtained from the same rainfall event definition was derived as the second most optimal threshold. Therefore, in the study of the rainfall threshold of the local scale, the cumulative rainfall-duration threshold is the optimum discrimination condition which can increase the prediction accuracy of the possibility of landslide occurrence and minimize the possibility of the landslide false alarm than the rainfall intensity-duration threshold. This shows that cumulative rainfall is the most important factor in the result of correlation analysis between the occurrence of landslides or number of landslides and rainfall factors, and the correlation coefficient of rainfall intensity is the lowest. In addition, the occurrence of landslides was more correlated with the hourly maximum rainfall than rainfall duration, and the number of landslides was more correlated with rainfall duration than the hourly maximum rainfall. Landslides in Chuncheon began to occur in longer rainfall durations and more cumulative rainfall in comparison with the threshold values throughout Korea.

내재파산유예수준을 이용한 부보금융기관의 자본건전성 평가

김영진,김봉준 한국재무관리학회 2011 財務管理硏究 Vol.28 No.4

Ronn and Verma(1986) assumed capital forbearance threshold as exogeneous and constant. But this assumption does not coincide with reality. As the result, the measurement error of capital forbearance threshold may amplify the estimation error of deposit insurance premium. We found that relative deposit insurance premium was much dependent on the assumption of capital forbearance threshold. To overcome this problem we suggestd to substitute implied capital forbearance threshold for deposit insurance premium as the criteria to categorize financial intermediaries according to their financial risk. Implied capital forbearance threshold can be derived from simultaneous equations based on option premium formulae by Ronn and Verma (1986). Implied capital forbearance threshold has the economic meaning of capital forbearance threshold justifying actual deposit insurance premium. As the empirical result, the estimate of implied capital forbearance threshold showed statistically significant and economically valid relations with BIS capital ratio, fixed loan rate, net interest margin representing the capital soundness of financial intermediary. This implies that implied capital forbearance threshold reflects market information about capital soundness of financial intermediary better than deposit insurance premium assuming constant capital forbearance threshold. Therefore, we concluded that implied capital forbearance threshold can be used as the valid indicator monitoring moral hazard of executives and capital soundness of financial intermediary. 본 연구는 Ronn and Verma(1986) 모형과 Lee, Lee and Yu(2005) 모형을 사용하여 현실의 적용보험료율을 정당화하는 감독기관의 파산유예수준(capital forbearance threshold)을 내생적으로 도출하였다. 실증결과 내재파산유예수준(implied capital forbearance threshold)은 금융기관의 자본적정성 지표와 경제적으로 타당한 관계를 나타내었으며 이는 10% 수준에서 통계적으로 유의하였다. 따라서 내재파산유예수준이 부보금융기관의 자본건전성을 모니터링하는 지표로 사용될 수 있다는 시사점을 발견하였다. 국내 부보금융기관을 대상으로 내재파산유예수준 추정치를 분석한 결과는 다음과 같다. 첫째, 내재파산유예수준은 1997년 11월 외환위기가 발생하기 3~4개월 전에 일부 부실금융기관에 대해 조기경보를 발하였다. 둘째, 외환위기 이후 공적자금의 투입 및 금융구조조정으로 국내 금융산업의 자본건전성이 많이 제고되었으나 해외적 요인에 취약한 모습이 발견되었다. 셋째, 공적자금이 투입된 금융기관을 부실기업으로 정의하여 건전기업과의 차이를 분석한 결과 일부 은행의 경우 감독기관에 의한 판단과 내재파산유예수준에 의한 판단이 일치하지 않았다. 이는 외환위기 이후 은행산업의 구조조정에서 이루어진 일부 소규모 은행에 대한 정책적 청산이 효율성에 근거한 시장의 판단과 상이하였다는 것을 의미하며 내재파산유예수준이 감독기관의 주관적 판단을 보완하는 객관적 시장평가지표로 사용될 수 있다는 것을 시사한다.

임계이익의 충족이 신용평가에 미치는 영향

심호석 韓國公認會計士會 2012 회계·세무와 감사 연구 Vol.54 No.2

This paper examines the relation between beating earnings thresholds and credit ratings. Specifically, I conduct empirical tests on whether beating earnings thresholds has a positive impact on credit ratings. The earnings thresholds that have been frequently suggested in the previous research are three : the zero earnings, the prior period's earnings, and finally the analyst's earnings forecasts. These earnings numbers have been mentioned as the target levels of earnings that managers wish to reach. The target numbers have important implications in that those can be an heuristic criterion for the decision makings of interested parties, so that managers have incentives to manage their performance beyond the target numbers. Actually, many scholars have mentioned the importance of those numbers in investors' decision makings. Degeorge et al.(1999) provide some theory why the earnings thresholds are of concern, which is derived from the behavioral aspects of human thoughts. They say that many of outsiders show 'a threshold mentality'. In a range of circumstances, individuals perceive continuous data in a discrete form; indeed, the tendency of dividing the world into categories is a common aspect of human thought(Glass and Holyoak, 1986, p.149). Degeorge et al.(1999) mention that positive numbers are fundamentally different from non-positive numbers in the process of human thoughts. Second, they are based on prospect theory. The theory tell us that individuals trying to choose risky alternatives behave as if they evaluate performances as changes from the reference point(Kahneman and Tversky, 1979). If the preference of managers, investors, and board of directors was consistent with the prediction of prospect theory, then managers would have incentive plans regarding earnings thresholds. The earnings thresholds managers want to reach are likely to be the reference points in the value function of interested parties. Third, the earnings thresholds are important targets because common people tend to rely on the rule of thumb to reduce transaction costs. For experts such as analysts, bankers, and raters who have the discreteness of decision-makings, the thresholds will become more important in real business environments. Most of the previous studies have tested the threshold-beating effects in the stock market(Bartov et al., 2002), but this study aims to investigate some effects in the debt market. Specifically, I try to test the impact of beating earnings benchmarks on credit ratings. This study specifies empirical models in order to test threshold-beating effects. Credit ratings are the dependent variable, and dummies, whether earnings thresholds are beaten, are independent variables. I add controlling factors into the models that is likely to affect credit ratings. According to the regression results, reporting profits or increasing earnings appears to have a positive impact on credit ratings, and beating the analysts' earnings forecasts shows no impact : I find significance in the coefficients of dummy variables that indicates reporting profits or losses and reporting increasing or decreasing earnings but I don't find significance in the coefficient of the dummy variable that represents beating the analysts' forecasts. The profit-reporting effect appears bigger than the earnings-increasing effects : the coefficient of the profit-loss dummy is estimated significantly larger than that of the earnings increase-decrease dummy. I also find that firms with high default risk in general have lower credit ratings but, when beating earnings thresholds, their credit ratings turn positive relative to firms with low default risk ; I measure this effect by using the interaction variable of a default-risk variable and main dummy variables of beating earings thresholds. which show a significantly positive coefficient as expected. Furthermore, I conduct the same empirical tests using data of credit ratings of commercial paper, finding similar results to bond credit ratings. Other than that, I test the threshold-beating effects through earnings management in debt market. I compare credit ratings of both firms that beat the thresholds with earnings management and firms that beat the thresholds without earnings management. The results tell us that firms that beat the thresholds with earnings management do not suffer from significantly unfavorable effects, relative to firms that beat the thresholds without earnings management, which is against general expectations. I interpret this result cautiously as debt market do not care about how to beat earnings thresholds. I consider some implications of this study as an empirical research testing the effects of beating earnings thresholds on credit ratings in debt market. The existing literature have examined the threshold-beating effects in stock market but I extend the range of studies to debt market. The threshold-beating may have different effects on between the stock and debt market(Jiang, 2008), because of the differences of structures of payoffs and utilities between stockholders and debtholders. Brown and Caylor(2005) find in stock market that beating analyst's forecasts has the largest effect on stock returns, but I find comparative results in debt market that reporting profits has the largest effect on credit ratings. 본 논문은 임계이익의 충족과 신용평가의 관계를 실증적으로 연구한다. 구체적으로 기업이 임계이익(earnings thresholds)을 충족하였을 때 신용평가(credit ratings)에 긍정적인 영향을 미치는지 검증한다. 임계이익은 선행연구에서 일반적으로 기술하는 세 가지 이익수치를 말한다, 즉 제로이익(the zero earnings), 전기이익(the prior period's earnings), 재무분석가 이익예측치(the earnings forecasts)를 지칭한다. 이 이익수치들은 기업이 달성하여야 할 최소한의 목표수준으로 인식된다. 이 수치들은 정보이용자들의 행동을 유발하는 의사결정기준(an heuristic)이 될 수 있으므로 경영자들은 이 목표이익수치를 달성하려는 동기를 지닌다. 선행연구들은 주식시장에서 임계이익의 충족효과를 검정해 왔으나, 본 연구는 우리나라 부채시장에서 그 효과를 검정하는 것이 목적이다. 회귀분석결과에 의하면, 흑자보고와 이익증가보고가 신용평가에 긍정적인 영향을 주는 것으로 밝혀졌으며, 이익예측치 충족은 영향력이 없는 것으로 나타났다. 흑자보고의 효과는 이익증가보고와 이익예측치 충족의 효과보다 더 큰 것으로 드러났다. 채무불이행위험은 일반적으로 신용등급에 부정적인 영향을 미치지만, 채무불이행위험이 높은 기업이 임계이익을 충족시켰을 때, 채무불이행위험이 낮은 기업에 비해 신용등급에 긍정적인 영향을 미치는 것으로 나타났다. 아울러 기업어음(CP)에 대한 신용등급을 이용하여 동일한 검정을 해 본 결과, 회사채 신용등급과 유사한 결과가 나타났다. 추가하여 이익조정을 통한 임계이익 충족효과를 검정하였다. 이익조정을 통해 임계이익을 충족한 기업과 이익조정 전부터 임계이익을 충족한 기업 간에 신용평가의 차이가 있는지 비교하였다. 그 결과 이익조정을 통해 임계이익을 충족한 기업이 이익조정 전부터 임계이익을 충족한 기업에 비해 차별적으로 불리한 영향을 받지는 않는 것으로 드러났다. 본 연구는 임계이익 충족효과를 부채시장에서 검정하였다는 데 의의가 있다. 기존의 선행연구들은 주식시장에서 임계이익 충족효과를 검정하였으나 본 연구는 부채시장으로 확장하였다. 임계이익충족효과는 주식시장과 부채시장에서 다를 수 있다. 이는 채권소유주와 지분소유주간의 보상구조가 다르고 그에 따른 효용이 다르다는 데 연유한다. 채권시장에서는, 주식시장과 달리, 흑자보고효과가 가장 큰 것으로 밝혀졌다. 이 점은 본 연구의 기여라 할 수 있을 것이다.

$^{99m}Tc$-DMSA 신장 검사에서 ROI 설정 방법에 따른 정량분석 차이에 관한 연구

이종훈,심동오,Lee, Jong-Hun,Shim, Dong-Oh 대한핵의학기술학회 2010 핵의학 기술 Vol.14 No.1

핵의학 기술학의 발전은 많은 변화를 가져왔다. 하드웨어적인 발전이 많이 있었고 또한 소프트웨어의 발전도 핵의학 기술학 발전에 지대한 공을 세웠다. 소프트웨어의 발전으로 그 동안 수동으로 설정해야 했던 많은 ROI를 자동으로 설정할 수 있게 되었다. automated ROI가 manual ROI와 어떠한 정량분석의 차이를 가지고 있는지 알고자 한다. 분석은 3가지의 분석을 통해 결론을 도출하고자 하였다. 분석 1은 신장 automated ROI와 신장 manual ROI를 비교하였다. 분석 2는 threshold의 크기변화에 따른 차이를 조사하였다. 육안적 판단으로 신장의 외곽선보다 큰 threshold ROI(이하 A threshold), 외곽선과 일치하는 threshold ROI(이하 B threshold), 외곽선보다 작은 threshold ROI(이하 C threshold)를 설정하여 신장의 기능 값을 구하여 이를 비교 하였다. 분석 3은 automated background ROI를 세 가지 full, half, quarter로 분류하여 이에 따른 기능값의 차이를 분석하였다. 분석 1에서 신장 automated ROI와 신장 manual ROI간에 통계적으로 유의한 차이는 보이지 않았다. 그러나 분석 2에서 C threshold는 각 A threshold와 B threshold 간에 유의한 차이 (p<0.01)를 보였다. 분석 3은 분석 1을 통해 얻어진 결론을 토대로 시행되었다. 각 3가지 형태의 background에서 full background가 통계적으로 유의한 차이를 보였다(p<0.05). automated ROI가 manual ROI와 유의한 차이를 보지 않아 입증된 결과는 사용자의 편의와 객관성이 증대될 것으로 기대된다. 분석 2에서는 신장의 외곽선보다 작게 설정된 threshold는 신장의 외곽선보다 크게 설정된 threshold보다 큰 오차를 가질 수 있다는 것을 예상할 수 있다. 분석 3은 신장 주변의 간과 비장에 background가 증가되어 초래된 결과로 예상한다. Purpose: The nuclear medicine technology has been changed. The hard ware is developed so much. Also the soft ware performs a meritorious deed for the development of nuclear medicine technology. We could use the automated region of interest (ROI) instead of manual ROI. We want to know that what difference of quantitative analysis is there between automated ROI and manual ROI Materials and Methods: There are three experimental to make results. The first is what comparing the renal automated ROI and manual ROI. The second is that we compared three threshold ROI that size is difference each others with visible decision. The third is that we compared full, half, quarter automated background, and survey relative function. Results: Although the first has statistically not significant difference, the second and third have significant difference. Threshold, setting smaller threshold then renal outline or bigger, has statistically significant difference (p<0.01). The third is performed with the first experimental. Full background has significant difference, comparing each three type background (p<0.05). Conclusion: The results that there is not significant difference between automated ROI and manual ROI will increase objectivity and operator's convenience. We could know that smaller threshold then renal out line has significant difference in the second experimental. And the third experimental has results because of a increased background nearby live and spleen.