CP강의 디스크레이저 용접부의 경도특성에 미치는 B 함유량의 영향

박태준,유정우,강준일,한태교,진광근,강정윤,Park, Tae-Jun,Yu, Jung-Woo,Kang, Jun-Il,Han, Tae-Kyo,Chin, Kwang-Keun,Kang, Chung-Yun 대한용접접합학회 2011 대한용접·접합학회지 Vol.29 No.1

CP steel was developed to reduce the weight and increase the strength of car body. When it was welded using state-of-the-art disk laser welding, the effected of boron on the microstructure and hardness were investigated. Welding power was fixed at 3.5kW and welding speeds were 4,8 and 12m/min. Full penetration occurred in welding speed of 12m/min and weld bead was almost unchanged with boron contents. But the welding speed increased, the upper and lower bead were narrowed. In a welding speed of more than 8m/min, underfill defects were formed on the bead bottom. The hardness of weld zone was somewhat fluctuation in fusion zone and HAZ showed the highest hardness values. The hardness of each region showed little change with the boron contents, and softening phenomenon occurred in the HAZ near the base metal regardless of the boron contents.

Field Voice

박태준,Park, Tae-Jun 대한전기협회 2011 전기저널 Vol.416 No.-

Al-Si 용융도금된 11%Cr 페라이트 스테인리스강, STS409L GTA 용접부의 미세조직과 경도

박태준,공종판,나혜성,강정윤,엄상호,김정길,우인수,이종섭,Park, Tae-Jun,Kong, Jong-Pan,Na, Hye-Sung,Kang, Chung-Yun,Uhm, Sang-Ho,Kim, Jeong-Kil,Woo, In-Su,Lee, Jong-Sub 대한용접접합학회 2010 대한용접·접합학회지 Vol.28 No.3

Ferritic stainless steels, which have relatively small thermal expansion coefficient and excellent corrosion resistance, are increasingly being used in vehicle manufacturing, in order to increase the lifetime of exhaust manifold parts. But, there are limits on use because of the problem related to cosmetic resistance, corrosions of condensation and high temperature salt etc. So, Aluminum-coated stainless steel instead of ferritic stainless steel are utilized in these parts due to the improved properties. In this investigation, Al-8wt% Si alloy coated 409L ferritic stainless steel was used as the base metal during Gas Tungsten Arc(GTA) welding. The effects of coated layer on the microstructure and hardness were investigated. Full penetration was obtained, when the welding current was higher than 90A and the welding speed was lower than 0.52m/min. Grain size was the largest in fusion zone and decreased from near HAZ to base metal. As welding speed increased, grain size of fusion zone decreased, and there was no big change in HAZ. Hardness had a peak value in the fusion zone and decreased from the bond line to the base metal. The highest hardness in the fusion zone resulted from the fine re-precipitation of the coarse TiN and Ti(C, N) existed in the base metal during melting and solidification process and the presence of fine $Al_2O_3$ and $SiO_2$ formed by the migration of the elements, Al and Si, from the melted coating layer into the fusion zone.

스마트 스피커 대상 가청 주파수 대역을 활용한 적대적 명령어 공격 방법 제안

박태준,문종섭,Park, Tae-jun,Moon, Jongsub 한국인터넷정보학회 2022 인터넷정보학회논문지 Vol.23 No.4

최근 스마트 스피커의 기능이 다양해지면서 스마트 스피커의 보급률이 증가하고 있다. 보급이 증가함에 따라 스마트 스피커에 대해 비정상적인 행위를 발생시키는 기법이 제안되고 있으며 여러 가지 공격 중 Voice Controllable System(VCS)에 대해 비정상적인 행위를 발생시키는 DolphinAttack은 초음파(f>20kHz)를 이용하여 사용자의 인식 없이 VCS를 제3자가 제어하는 방법이다. 하지만 기존의 제어 방법은 초음파 대역을 사용하기 때문에 초음파 신호를 출력할 수 있는 초음파 스피커나 초음파 전용 장비의 설치가 필요했다. 본 논문에서는 추가적인 장비, 즉, 초음파 장비의 설치 없이 사람의 가청 주파수 대역이지만 노화에 의해 듣기 힘든 주파수(18k~20kHz)로 변조된 음성신호를 출력하여, 스마트 스피커를 제어하는 방법을 제안한다. 스마트 스피커의 경우 마이크가 내장되어 있어, 변조된 음성신호를 수신할 수 있다. 본 논문에서 제안한 방법으로 수행한 결과, 가청 대역임에도 불구하고 사람은 음성명령을 인식하지 못하였으며, 스마트 스피커에 대해 82~96%의 확률로 제어가 가능했다. Recently, the functions of smart speakers have diversified, and the penetration rate of smart speakers is increasing. As it becomes more widespread, various techniques have been proposed to cause anomalous behavior against smart speakers. Dolphin Attack, which causes anomalous behavior against the Voice Controllable System (VCS) during various attacks, is a representative method. With this method, a third party controls VCS using ultrasonic band (f>20kHz) without the user's recognition. However, since the method uses the ultrasonic band, it is necessary to install an ultrasonic speaker or an ultrasonic dedicated device which is capable of outputting an ultrasonic signal. In this paper, a smart speaker is controlled by generating an audio signal modulated at a frequency (18 to 20) which is difficult for a person to hear although it is in the human audible frequency band without installing an additional device, that is, an ultrasonic device. As a result with the method proposed in this paper, while humans could not recognize voice commands even in the audible band, it was possible to control the smart speaker with a probability of 82 to 96%.

간 이식 예정 환자의 구강건강상태 및 치과치료 요구도에 관한 연구

박태준,고홍섭,Park, Tae-Jun,Kho, Hong-Seop 대한안면통증구강내과학회 2009 Journal of Oral Medicine and Pain Vol.34 No.1

Liver transplantation is definitive treatment for the patients suffering from hepatitis, severe liver cirrhosis and liver cancer. In these patients, systemic infections under immunosuppression may occur easily. Therefore, primary object of dental treatments before liver transplantation is absolute removal of oral infection source. In addition, comprehensive dental management plan is essential for success of liver transplantation. The present study has been performed to investigate decayed, missing and filled permanent teeth index(DMFT index), degree of oral hygiene, past medical history, need of dental treatment, completion of dental treatment need and time interval between dental visit and operation date of liver transplantation in liver transplant candidates. Obtained results were as follows; 1. Decayed teeth of the patients were 2.68, missing teeth were 4.02 and filled teeth were 3.42. DMFT index was 10.12. 2. Twenty percents of patients showed moderate to severe food impactions, 42.2% of patients had moderate to heavy calculus and 37.8% of patients displayed gingival inflammation with swelling. 3. Patients needed periodontal treatments more than any other dental treatments. Periodontal treatments were needed for 88.9% of patients, operative & endodontic treatments were 46.7% of patients and 33.3% of patients needed for oral & maxillofacial surgical treatments. 4. Among 90 patients, time interval between scheduled operation date of liver transplantation and dental visit was within 2 weeks for 32.2% of patients, within 1 week for 20.0% of patients. In conclusion, most liver transplant candidates needed dental treatments for removal of potential infection sources. However because of insufficient interval between dental visit and operation date, they had taken liver transplantation procedures without comprehensive dental management. Development of preventive and comprehensive dental management program is mandatory for these patients. Cooperative interdisciplinary management will play a positive role for successful liver transplantation.

N타입 결정질 실리콘 웨이퍼 두께 및 알루미늄 페이스트 도포량 변화에 따른 Bowing 및 Al doped p⁺ layer 형성 분석

박태준,변종민,김영도,Park, Tae Jun,Byun, Jong Min,Kim, Young Do 한국재료학회 2015 한국재료학회지 Vol.25 No.1

In this study, in order to improve the efficiency of n-type monocrystalline solar cells with an Alu-cell structure, we investigate the effect of the amount of Al paste in thin n-type monocrystalline wafers with thicknesses of $120{\mu}m$, $130{\mu}m$, $140{\mu}m$. Formation of the Al doped $p^+$ layer and wafer bowing occurred from the formation process of the Al back electrode was analyzed. Changing the amount of Al paste increased the thickness of the Al doped $p^+$ layer, and sheet resistivity decreased; however, wafer bowing increased due to the thermal expansion coefficient between the Al paste and the c-Si wafer. With the application of $5.34mg/cm^2$ of Al paste, wafer bowing in a thickness of $140{\mu}m$ reached a maximum of 2.9 mm and wafer bowing in a thickness of $120{\mu}m$ reached a maximum of 4 mm. The study's results suggest that when considering uniformity and thickness of an Al doped $p^+$ layer, sheet resistivity, and wafer bowing, the appropriate amount of Al paste for formation of the Al back electrode is $4.72mg/cm^2$ in a wafer with a thickness of $120{\mu}m$.

연부조직육종

박태준(Tae Jun Park),민현식(Hyun Sik Min),서보양(Bo Yang Suh),심민철(Min Chul Shim),권굉보(Koing Bo Kwun) 대한외과학회 1987 Annals of Surgical Treatment and Research Vol.33 No.2

기업 자본적지출 공시 주위에서의 기관투자자 거래행태

박태준 ( Tae-jun Park ),박진모 ( Jin-mo Park ) 한국생산성학회 2020 生産性論集 Vol.34 No.1

This study examines the institutional investor’s trading behavior around corporate’s capital expenditure announcements in terms of free cash flow hypothesis and the investment opportunities hypothesis. Jensen(1986) argues that managers will invest free cash flow in wasteful investments rather than pay it out to shareholders. The potential agency costs of capital expenditure are arguably higher for high-free cash flow firms. On the other hand, capital expenditure by low-free cash flow firms increase the chance the firm will seek new external financing. Free cash flow agency costs may depend on the firm's investment opportunities. Prior research shows that market reaction to a capital expenditure announcement is related to a firm’s investment opportunities, Tobin's q. Tobin's q is the ratio of the market value of the firm's assets to their replacement cost. There are evidences somewhat weak, supportive of the free cash flow hypothesis in explaining capital expenditure announcement-period returns. So, we investigate whether investment opportunities and free cash flow play an important role in explanation of the market response to such announcements. In other words, we tests the market response on capital expenditure announcements through investment opportunities hypothesis and free cash flow hypothesis. Most of the existing research on this area has used U.S data, but little is known about Korean evidence. Using KOSPI data over the period of 2000-2013, this paper mostly analyses the samples separated by Tobin's q and free cash flow. The main results are as follows; First, institutional investors tend to buy shares in the disclosure of capital expenditures by companies with many future investment opportunities and vice versa. But this relation is not significant in the OLS analysis. Second, low-free cash flow and high-q firms have a significant positive abnormal trading volume around the disclosure of capital expenditures, meanwhile high-free cash flow and low-q firms have an significant negative abnormal trading volume. But analysis for personnel investor’s trading volume shows insignificant relation with free cash flow or future investment opportunities. These results mean that institutional investors sell shares for companies with relatively small free cash flows and many future investment opportunities, while buy shares for those with relatively large free cash flows and little future investment opportunities.

펀치 생검으로는 정확히 진단되지 않았으나 더모스코피를 통해 확진에 도움이 된 표재성 기저세포암 1예

박태준 ( Tae Jun Park ),김고은 ( Ko Eun Kim ),정재영 ( Jae Young Jeong ),유화정 ( Hwa Jung Ryu ),손상욱 ( Sang Wook Son ),김일환 ( Il-hwan Kim ),문혜림 ( Hye Rim Moon ) 대한피부과학회 2020 大韓皮膚科學會誌 Vol.58 No.6

Basal cell carcinoma is a common cancer and has been reported to account for approximately 80% of non-melanoma skin cancers. Superficial basal cell carcinoma occurs mainly in the trunk or limbs and is characterized by clinical features of scaly erythema with or without epidermal atrophy. These clinical features require differentiation from those of other benign and malignant skin diseases. Recently, specific dermoscopic findings of basal cell carcinoma have been helpful for diagnosis. Common dermoscopic findings of superficial basal cell carcinoma include superficial telangiectasia and maple leaf-like areas. Herein, we report a case of superficial basal cell carcinoma that was not diagnosed by punch biopsy but by dermoscopy. (Korean J Dermatol 2020;58(6):419∼422)

투자기회와 잉여현금흐름이 자본적지출 공시에 미치는 영향

박태준(Park Tae-jun) 한국국제회계학회 2016 국제회계연구 Vol.0 No.65

본 연구의 목적은 기업의 자본적지출 공시에 대한 시장반응을 살펴보고, 이러한 시장반응을 규명하는데 투자기회 및 잉여현금흐름의 중요한 역할을 검증하는 것으로 즉, 기업의 자본적지출공시에 대한 시장반응을 투자기회가설과 잉여현금흐름가설을 통해 검증하는 것이다. 2001년부터 2013년까지 한국거래소 유가증권시장에서 자본적지출 공시기업을 대상으로 토빈 q와 잉여현금흐름으로 구분하여 분석을 진행한 주요 결과는 다음과 같다. 첫째, 자본적지출 공시일에 통계적으로 유의한 양의 초과수익률이 나타났다. 둘째, 높은 q 기업은 통계적으로 유의한 양(+)의 누적초과수익률을 보이는 반면, 낮은 q 기업은 음(-)의 누적초과수익률을 보이나 통계적인 유의성이 없었다. 셋째, 잉여현금흐름이 적고 높은 q 기업은 소표본 중에서 가장 높은 누적초과수익률을 보이며 통계적으로 유의하게 나타난 반면, 잉여현금흐름이 많고 낮은 q 기업은 소표본 중 누적초과수익률이 가장 낮지도 않고 통계적인 유의성도 없는 것으로 나타났다. 넷째, 횡단면 회귀분석을 실시한 결과, 미래 투자기회의 대용변수인 토빈 q 더비변수는 누적초과수익률과 정(+)의 관계를 보이며 통계적으로 유의성이 있는 반면, 잉여현금흐름변수는 역(-)의 관계를 보이고는 있으나 통계적인 유의성이 없었다. 이상의 결과는 미래 투자기회가 많은 기업이 자본적지출 공시를 하면 시장가치가 높게 형성되지만 미래 투자기회가 적은 기업의 경우에 그렇지 않다는 투자기회가설이 지지되고 있으며, 다른 잠재적 요인들을 통제한 후에도 여전히 지지되고 있는 것으로 나타났다. 반면에, 잉여현금흐름가설은 자본적지출 공시에 대한 주주 부의 효과를 제대로 설명하지 못함에 따라 지지되지 않고 있다. This paper examines the market response to announcements of capital expenditure. Also, this paper investigates whether investment opportunities and free cash flow play an important role in explanation of the market response to such announcements. In other words, this paper tests the market response on capital expenditure announcements through investment opportunities hypothesis and free cash flow hypothesis. Using KOSPI data over the period of 2001-2013, this paper mostly analyses the samples separated by Tobin"s q and free cash flow. The main results are as follows. First, the announcements of capital expenditures are associated with significant positive abnormal stock returns. Second, high-q firms have a significant positive abnormal returns, on the other hand, low-q firms have an insignificant negative abnormal returns. Third, low-free cash flow and high-q firms have a significant positive abnormal returns, the highest among the four subsamples. Meanwhile, high-free cash flow and low-q subsample has an insignificant positive abnormal returns, against free cash flow hypothesis expectation. Fourth, Tobin’s q dummy variable is positively and significantly related to cumulative abnormal returns of the announcements. This results support the investment opportunities hypothesis that high-q firms with favorable investment opportunities have significantly positive response to the announcements of capital expenditures whereas low-q firms with poor investment opportunities have negative response to such announcements and hold even after controlling for other potential explanatory factors. In contrast, the results find no support for the free cash flow hypothesis. that does not explain the wealth effect of announcements of capital expenditures.