49 research outputs found
Do audit fees and audit hours influence credit ratings?: A comparative analysis of Big4 vs Non-Big4
We examine the relationship between credit ratings / changes and audit fees (hours) for Big4 and
Non-Big4 firms. Audit fee (hours) may be considered as a default risk metric for credit ratings agencies.
However, firms audited by Big4 are larger, better performing and operate with lower leverage compared
to firms followed by Non-Big4. Therefore, the association between audit fee (hours) may be different for
firms followed by Big4 and Non-Big4 audit firms. We find that there is a negative association between
audit fees and credit ratings for firms followed by Big4 audit firms. However, we find an insignificant
relation for firms followed by Non-Big4. We conjecture the different association due to the Big4 firms
having more robust accounting procedures; Big4 firms must offer competitive audit fees because they
are engaged in fierce competition with other Big4 firms. Moreover, Big4 and Non-Big4 firms have
different relationships with their clients because Non-Big4 firms are more income dependent on their
clients.
Using a sample of 1,717 firmโyear observations between 2002 and 2013, we establish a relation
between audit fees in period t and credit ratings in period t+1, for firms followed by Big4 auditors. We
do not find a significant relation for firms followed by Non-Nig4 firms, suggesting that credit ratings
agencies perceive audit fee differently for Big4 and Non-Big4 firms. Client firms followed by Big4 auditors
that experience a credit rating change in period t+1 pay lower audit fees in period t compared to firms
that do not experience a credit rating change. Our additional analysis suggests a different association
between firms audit fees and firm performance for firms that experience a credit rating increase and
decrease. Firms that experience a credit ratings increase in period t+1 have strong performance and
lower audit fees in period t. On the other hand, firms that experience a credit rating decrease have
weak financial performance and negative audit fees compared to firms that do not experience a credit
ratings change. Our results suggest that audit fees combined with financial performance influence a
credit ratings agency' perception of default risk
๋ฉํฐ๋ฏธ๋์ด ํ๋ก์ธ์์ ASIC ๊ตฌํ
ํ์๋
ผ๋ฌธ(์์ฌ)--์์ธ๋ํ๊ต ๋ํ์ :์ ๊ธฐ.์ปดํจํฐ๊ณตํ๋ถ,2001.Maste
๊ฑด์์์ฑ ์๊ณ ๊ธฐ ํฌ๋ฌ์คํธ์ ํญ์ฐํ ๋ฐ ACE ์ ํดํ์ฑ๊ณผ ํจํฐ ์ ์กฐ์ ํ๋ฏธ์ฆ์ง์ ๋ก์์ ํ์ฉ
ํ์๋
ผ๋ฌธ (์์ฌ)-- ์์ธ๋ํ๊ต ๋ํ์ : ๋์
์๋ช
๊ณผํ๋ํ ๋์๋ช
๊ณตํ๋ถ, 2018. 8. ์กฐ์ฒ ํ.The objective of present experiments was 1) to determine the antioxidant and angiotensin Iโconverting enzyme (ACE) inhibitory activity of the crust of dry-aged beef, and 2) to find the way of utilizing the crust as a flavor enhancer in the manufacturing beef patty.
Experiment I. Evaluation of antioxidant and ACE inhibitory activity of crust derived from dry aged beef
Moisture evaporation of meat surface in dry aging process inevitably produces crust which is cut and discarded before consumption. Antioxidant activity, ACE inhibitory activity, and protein profile of the crust were evaluated compared with un-aged, wet-, and dry-aged beef. The antioxidant activity was determined using 2,2-diphenyl-1-picrylhydrazyl (DPPH) and 2,2-azino-di-(3-ethylbenzthiazoline sulphonate) (ABTS) radical scavenging, ferric reducing antioxidant power (FRAP), and ferrous ion chelating activity. The crust samples showed the greatest (P<0.05) antioxidant activity resulting from the 3 different mechanisms of action (radical scavenging, non-radical redox potential activity, and metal cheating) as antioxidant and ACE inhibitory activity among the treatment. Protein bands with small molecular weight indicating potent bioactivity were appeared in myofibrillar protein profile of the crust sample. The lowest (P<0.05) ACE inhibitory activity was observed in un-aged beef. Based on results from this study, it could be suggested the crust, usually recognized as discarded portion of dry-aged beef, can be utilized in various areas as functional ingredient possessed antioxidant and ACE inhibitory activity.
Experiment II. Application of the crust from dry-aged beef on beef patty and its quality assessment
The aim of this study was to find the way of utilizing the crust in meat products to enhance sensory characteristic and to reduce expensive waste. Total of four sirloins were dry-aged for 28 days at 4ยฐC (75% relative humidity). The crust was obtained from surface of the dry-aged beef and prepared as powdered form after freeze-drying. Patties were prepared with 75% ground beef, 20% beef fat, 0.3% salt, and the crust [0 (control) and 5%w/w] The patties were packaged with aerobic method and stored at 4ยฐC for 4 or 6 days with 2-day interval, respectively. The patties with the crust showed higher score in flavor, tenderness, and acceptability by sensory panel compared to control. In addition, different profile was observed in electronic nose analysis between with and without crust group. In conclusion, the crust from dry-aged beef could be used as flavor enhancer in meat products by providing beefy and palatable flavor without long period of dry aging time as meat industry practiced commonly.Chapter I. General Introduction 1
Chapter II. Evaluation of antioxidant and ACE inhibitory activity of crust derived from dry aged beef 6
2.1. Introduction 6
2.2. Materials and Methods 7
2.2.1. Meat Sample preparation 7
2.2.2. Extraction 8
2.2.3. Antioxidant activity 8
2.2.3.1. DPPH assay 9
2.2.3.2. ABTS assay 9
2.2.3.3. FRAP assay 10
2.2.3.4. Ferrous ion chelating activity assay 10
2.2.4. ACE inhibitory activity 11
2.2.5. SDS-Page 12
2.2.6. Statistical analysis 13
2.3. Results and Discussion 14
2.3.1. Antioxidant activity of meat extracts obtained from four different beef samples 14
2.3.1.1. Radical scavenging activity 14
2.3.1.2. Ferric ions reducing power 17
2.3.1.3. Metal chelating activity 17
2.3.2. ACE inhibitory activity 18
2.3.3. Protein profile using SDS-PAGE 20
2.4. Conclusion 21
References 22
Chapter III. Application of the crust from dry-aged beef on beef patty and its quality assessment 26
3.1. Introduction 26
3.2. Materials and Methods 28
3.2.1. Preparation of patties 28
3.2.2. Sensory evaluation 29
3.2.3. Electronic nose 29
3.2.4. Texture analysis 30
3.2.5. Total aerobic bacterial counts 30
3.2.6. Lipid oxidation 31
3.2.7. Statistical analysis 32
3.3. Results and Discussion 33
3.3.1. Sensory evaluation and electronic nose 33
3.3.2. Texture analysis 36
3.3.3. Total aerobic bacterial counts 38
3.3.4. Lipid oxidation 40
3.4. Conclusion 42
References 43
Chapter IV. Overall Conclusion 48
Summary in Korean 49
Acknowledgement 51Maste
NURBS ์์ ๊ณก๋ฉด์ ์ด์ฉํ ์๋ฃ ๋ชจ๋ธ ๋ณ๊ฒฝ ์์คํ ๊ฐ๋ฐ์ ๊ดํ ์ฐ๊ตฌ
Thesis (master`s)--์์ธ๋ํ๊ต ๋ํ์ :์ฐ์
๊ณตํ๊ณผ,2001.Maste
Low-power Temperature Sensor
MasterThis thesis describes a design of an ultra-low power temperature sensor suitable for wearable sensor interface. A low power bandgap reference generator circuit is combined with a 10b successive approximation register based analog-to-digital converter. The temperature sensor, designed with 0.35um technology, shows a resolution of 0.164โ in a conversion range of 0โ to 100โ. With a conversion time of 60ฮผs, the sensor consumes only 11.7nW from single 1.3V supply voltage at room temperature.๋ณธ ๋
ผ๋ฌธ์์๋ ๋ฎ์ ์ ๋ ฅ์ ์๋นํ์ฌ ๋์ ์ ํ๋๋ฅผ ๊ฐ์ง๊ณ ์จ๋๋ฅผ ์ธก์ ํ๊ธฐ ์ํ Temperature Sensor๋ฅผ ์ค๊ณํ์๋ค. ์ ์๋ temperature sensor๋ Bandgap Reference ์์ฑ ํ๋ก๋ฅผ ๋ณํํ์ฌ ์จ๋์ ๋น๋กํ๊ฑฐ๋ ๋ฐ๋น๋กํ ์ ์์ ๋ฐ๋ก ๋ถ๋ฆฌํ๊ณ ๊ฐ ์ ์์ ADC๋ก ์ฐ๊ฒฐํ์ฌ ๋์งํธ ๊ฐ์ผ๋ก ๋ณํํ๋ ๋ฐฉ๋ฒ์ผ๋ก ์จ๋๋ฅผ ์ธก์ ํ๋ค.
๊ธฐ์กด์ Bandgap reference ์์ฑ ํ๋ก์์๋ ์จ๋์ ์ ๋น๋กํ๋ PTAT ์ ์๊ณผ ๋ฐ๋น๋กํ๋ CTAT ์ ์์ ํฉํ์ฌ reference ์ ์์ ์์ฑํ์๋ค. ์ด๋ฌํ ํ๋ก๋ฅผ ๋ณํํ์ฌ PTAT ์ ์๊ณผ CTAT ์ ์์ ๋ฐ๋ก ๋ถ๋ฆฌํ์๋ค. PTAT ์ ์์ ๋ ๊ฐ์ diode๋ฅผ ๊ฑฐ๊พธ๋ก ์ฐ๊ฒฐํ์ฌ ์์ชฝ diode์ saturation ์ ๋ฅ๋ฅผ ์ด์ฉํ์๋๋ฐ ์ด ๊ฒฝ์ฐ saturation ์ ๋ฅ๋ฅผ ์ฌ์ฉํ๊ธฐ ๋๋ฌธ์ ์ ๋ฅ์ ํฌ๊ธฐ๊ฐ ๋งค์ฐ ์์ ์ ๋ ฅ ์๋น ๋ํ ์๊ฒ ํ ์ ์๋ค. CTAT ์ ์์ diode๋ฅผ ์ ๋ฐฉํฅ์ผ๋ก ์ฐ๊ฒฐํ๊ณ ์ ๋ฅ๋ฅผ ๊ฑฐ์ ์ผ์ ํ๊ฒ ์ ์ง์์ผ์ ์ป์๋ค.
ADC๋ SAR ํ์
์ ADC๋ฅผ ์ฌ์ฉ์ ํ์๋ค. SAR ํ์
์ ์ ๋ ฅ ์๋น๋ฅผ ์ต์๋ก ํ๊ณ ์ ํ ๋ ์๋ง์ ADC์ด๋ค. BGVRํ๋ก์์ ์์ฑํ PTAT์ CTAT์ ์์ ADC์ ๋ ์ฐจ๋ ์
๋ ฅ์ผ๋ก ์ฐ๊ฒฐํ์๋ค. ADC๋ด์ comparator๋ ์ฐจ๋ ์ ์์ ์ฐจ์ด๋ฅผ ์๊ฐ domain์ผ๋ก ์ฎ๊ฒจ์ ๋ ์ ํธ์ ์ ํ ์๋ ์ฐจ์ด๋ก ๋น๊ต๋ฅผ ์งํํ๋ค. ์ด๋ฌํ ๋ฐฉ์์ comparator๋ ๊ณต๊ธ ์ ์์ด ๋ฎ์์๋ก ๋์์ด ์ ๋๋ค๋ ์ฅ์ ์ด ์๋ค.
์ค๊ณ๋ Temperature sensor์ ์ด ์๋น ์ ๋ ฅ์ 11.7nW์์ผ๋ฉฐ, conversion time์ 60ฮผs๋ก ์ธก์ ์ด ๋์๋ค. ์ด๋ ํ์กดํ๋ ์จ๋ ์ผ์ ์ค ๊ฐ์ฅ ๋ฎ์ ๊ฐ์ ๋ํ๋ธ๋ค. ์์ผ๋ก ์ต์์ ์ ๋ ฅ์ ์๋ชจํ์ฌ ์ ๋ฐํ๊ฒ ์จ๋๋ฅผ ์ธก์ ํ ์ ์๋ ํฐ ๋ฐํ์ ๋ง๋ จํ ์ ์๋ ๊ฒ์ผ๋ก ์๊ฐ๋
HLA-I ์ ํฉ์ฑ์ ๋ฐ๋ฅธ ์ข ์ ๊ฐ์ํ ํ๊ฐ ๋ฐ ํฌ๋ช ์ธํฌ ์ ์ฅ ์ธํฌ ์์์ ๋ฉด์ญ ํน์ง์ ๋ฐ๊ฒฌ
Clear cell renal cell carcinoma (ccRCC) is a common histological subtype of renal cancer with a 107% increase in incidence over about 20 years and has distinct immunogenic characteristics. CcRCC has been reported to have an immune characteristic contrary to the conventional notion, such as short survival despite abundance of tumor-infiltrating lymphocytes. In tumor immunity, the HLA-I molecule leads to tumor suppression, which enables CD8+ T cells to recognize tumors by presenting neoantigen, a peptide containing mutations in tumor cells, on the cell surface. We investigated tumor acceleration by HLA-I zygosity through tumor occurrence analysis in clear cell renal cell carcinoma as well as pan-cancer. To evaluate the effectiveness of immune surveillance by T cells, we selected early tumors close to the time point of immune evasion, excluding tumor samples containing pathogenic factors that influence tumor development. The zygosity of HLA-I was classified into homozygous group and heterozygous group based on the heterozygosity of all three classical HLA-I genes. The acceleration was assessed using an accelerated failure time (AFT) model by HLA zygosity. As a result, it was confirmed that heterozygous HLA-I delayed the tumor development in pan-cancer except ccRCC. In contrast, ccRCC was found to occur earlier in heterozygous HLA-I patients than homozygous HLA-I patients. To determine the cause of ccRCC acceleration in heterozygous HLA-I, we classified allele loss in major tumor suppressor genes, VHL and PBRM1. Tumor acceleration of heterozygous HLA-I was found to occur in tumors containing biallelic loss of VHL, according to the theory of the secondary hit hypothesis that the loss of both alleles results in a phenotypic change. The association of heterozygous HLA-I and VHL biallelic loss on tumor acceleration was validated in an independent ICGC clear cell renal cell carcinoma cohort.
ํฌ๋ช
์ธํฌ ์ ์ฅ ์ธํฌ ์์ ์ฝ 20๋
๋์ ๋ฐ๋ณ๋ฅ ์ด 107% ์ฆ๊ฐํ๋ ์ ์ฅ์ ์ ํ์์ ํ ์ค ๊ฐ์ฅ ํํ ์์ด๋ฉฐ ๋๋ ทํ ๋ฉด์ญ์์ฑ ํน์ง์ ๊ฐ๋๋ค. ํนํ ํฌ๋ช
์ธํฌ ์ ์ฅ ์ธํฌ ์์ ์ข
์ ์นจ์ค T ๋ฆผํ๊ตฌ๊ฐ ๋ง์ด ์กด์ฌํ ๋ ์งง์ ์์กด์ ๋ณด์ด๋ ๋ฑ ๊ธฐ์กด์ ๊ฐ๋
๊ณผ๋ ๋ฐ๋๋๋ ๋ฉด์ญ ํน์ง์ด ๋ณด๊ณ ๋์ด์ ธ ์ ๋ค. ์ข
์ ๋ฐ์๊ณผ์ ์ค ๋ฉด์ญ๋ฐ์์ ์ค๋ช
ํ๋ ๋ฉด์ญํธ์ง ์ด๋ก ์ ์ต๊ทผ ํ๋ฐ ํ ์ฐ๊ตฌ๋๊ณ ์์ผ๋ฉฐ, ๋ฉด์ญํธ์ง ๋์ CD8+ T ์ธํฌ๋ ์ข
์์ธํฌ๋ฅผ ์ธ์งํ ๊ณ ์ข
์์ธํฌ ํน์ด์ ์ฌ๋ฉธ์ ์ ๋ฐํ๋ ๋ฐ์์ ํ๋ค. CD8+ T ์ธํฌ๊ฐ ์ข
์ ์ธํฌ๋ฅผ ์ธ์ํ๋ ๋ฐ์์๋ HLA-I ๋ถ์๊ฐ ์ค์ํ ์์ฉ์ ํ๊ฒ ๋๋๋ฐ, HLA-I๋ ์ข
์ ํน์ด์ ํญ์์ธ ์ ํญ์(neoantigen)์ ์ธํฌํ๋ฉด์ผ๋ก ํ์ง ํ์ฌ CD8+ T ์ธํฌ๊ฐ non-self ํญ์์ธ neoantigen์ ์ธ์งํ์ฌ ๋ฐ์์ ์ ๋ฐํ ์ ์๊ฒ ํ๋ค. ๋ณธ ์ฐ๊ตฌ๋ HLA-I ์ ํฉ์ฑ์ ์ํ ์ข
์ ๋ฐ๋ณ๊ฐ์๋๋ฅผ ์กฐ์ฌํ๊ธฐ ์ํด TCGA์ ๋๊ท๋ชจ์ ์ ๋ฐ์ดํฐ๋ฅผ ์ด์ฉํ์ฌ ํฌ๋ช
์ธํฌ ์ ์ฅ ์ธํฌ ์ ๋ฟ๋ง ์๋๋ผ ๋ฒ์(pan-cancer) ๋จ์์ ๋ถ์์ ์งํํ์๋ค. ๋ณ์ ์ฑ ์์ธ์ ํฌํจํ ์ข
์์ ์ ์ธํ์ฌ T ์ธํฌ์ ์ํ ๋ฉด์ญ๊ฐ์ํจ๊ณผ๋ฅผ ์ฃผ์ ํ๊ฒ ํ๊ฐํ์์ผ๋ฉฐ ๋ฉด์ญํํผ๊ฐ ์ผ์ด๋ ์์ ์์ ๊ฐ์ฅ ๊ฐ๊น์ด ์ด๊ธฐ ๋จ๊ณ ์ ์ข
์์ ์ ์ ํ์๋ค. HLA-I์ ์ ํฉ์ฑ์ HLA-I ์ ์ ์(HLA-A, B, C) ์ ํฉ์ฑ์ ๋ฐ๋ผ ๋ํ ์ ํฉ, ์ดํ ์ ํฉ HLA-I์ผ๋ก ๋ถ๋ฅ๋์๊ณ HLA-I ์ ํฉ์ฑ์ ์ข
์ ๊ฐ์๋๋ฅผ ์ธก์ ํ๊ธฐ ์ํด accelerated failure time ๋ชจ๋ธ์ด ์ฌ์ฉ๋์๋ค. ๊ทธ ๊ฒฐ๊ณผ ํฌ๋ช
์ธํฌ ์ ์ฅ ์ธํฌ ์์ ์ ์ธํ pan-cancer์์ ์ดํ ์ ํฉ HLA-I์ ์ข
์ ๋ฐ๋ณ์ด ๋ฆ์ถฐ์ง๋ ๊ฒ๊ณผ ์ฐ๊ด์ฑ์ด ์์๋ค. ๋์กฐ ์ ์ผ๋ก ํฌ๋ช
์ธํฌ ์ ์ฅ ์ธํฌ ์์์๋ ์ดํ ์ ํฉ HLA-I ํ์์์ ๋ํ ์ ํฉ HLA-I ํ์๋ณด๋ค ์ผ์ฐ ์ข
์์ด ๋ฐ๋ณํ๋ ๊ฒ์ด ๋ฐํ์ก๋ค. ์ดํ ์ ํฉ HLA-I์์ ์ข
์ ๊ฐ์ํ๊ฐ ์ผ์ด๋๋ ์์ธ์ ๊ท๋ช
ํ๊ธฐ ์ํด ํฌ๋ช
์ธํฌ ์ ์ฅ ์ธํฌ ์์์ ๊ฐ์ฅ ๋น๋ฒํ๊ฒ ๋์ฐ๋ณ์ด๊ฐ ๋ฐ์ํ๋ ์ข
์ ์ต์ ์ ์ ์ VHL๊ณผ PBRM1๋ฅผ ์ ๋ณํ์๋ค. VHL ์ ์ ์๋ ๋ ๋๋ฆฝ ์ ์ ์๊ฐ ๋ชจ๋ ์์ค ๋๋ฉด ํํํ ๋ณํ๊ฐ ์๊ธด๋ค๋ two-hit hypothesis๋ฅผ ๋ฐ๋ฅด๋ ๊ฒ์ด ๋ณด๊ณ ๋์ด ์์ผ๋ฉฐ, ์ดํ ์ ํฉ HLA-I์ VHL ์ด์ค ๋๋ฆฝ ์ ์ ์ ์์ค์ ํฌํจํ ๋ ๊ฒฝ์ฐ์์ ์ ์ํ ์ข
์ ๊ฐ์ํ๋ฅผ ๋ํ๋๋ค. ์ข
์ ๊ฐ์ํ์ ๋ํ ์ดํ ์ ํฉ HLA-I์ VHL ์ด์ค ๋๋ฆฝ ์ ์ ์ ์์ค์ ์ฐ๊ด์ฑ์ ๋
๋ฆฝ์ ์ธ ICGC ํฌ๋ช
์ธํฌ ์ ์ฅ ์ธํฌ ์ ์ง๋จ์์ ๊ฒ์ฆ๋์๋ค.open์
๋์ค ์ ๋ฅ๋ฅผ ์ด์ฉํ ์ด์ ์ ๋ ฅ ์จ๋ ์ผ์ ์ฐ๊ตฌ
DoctorThe performance of critical building blocks for ultra-low-power (ULP) applications often causes strong temperature dependencies. Since the temperature sensitivities need to be compensated, an on-chip temperature sensor is becoming one of the essential blocks in ULP system-on-chips (SoC). This thesis presents temperature sensors with a leakage-based bandgap-Vth reference. The first temperature sensor combines a leakage-based bandgap-Vth reference and an asynchronous SAR ADC. By sampling leakage-based biases directly by the SAR ADC, the sensor consumes 490pW at 20ยบC with a conversion time of 200ms and stably works with a 1-point calibration showing a peak-to-peak error of ยฑ2.35ยบC, a resolution of 0.59ยบC in a range of -10-to-100ยบC. The second temperature sensor uses a scaled reference voltage obtained by switched capacitor circuits and an on-chip leakage-based oscillator for internal clock generation. The SAR ADC operates with a scaled supply voltage by 1/2 generated by the switched capacitor. The sensor consumes 487pW with a conversion time of 128.6ms at 20ยบC. Peak-to-peak error is -3.43/2.77ยบC and ยฑ1.63ยบC after 1-point and 2-point calibration, respectively. In a temperature range of -30 to 100ยบC, the sensor shows resolution of 0.37ยบC that is about 60% improved, compared with the first sensor. The designed sensors are fabricated in 180nm CMOS process