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Blast injuries are divided into four classes, and inhalation injuries are a quaternary class of blast injuries. An inhalation injury can be critical to the patient due to the possibility of related complications, such as airway obstruction resulting from upper airway edema and pneumonia. Once diagnosed, an inhalation injury should be treated with early intubation, aerosol therapy, and antibiotics as soon as possible. We should suspect this injury in circumstances involving fire and especially bomb attacks in a military setting. Antipersonnel landmines designed to damage the soldier by amputating the leg can cause blast injuries, but their power is limited to the lower extremity. However, we found an inhalation injury in a victim whose leg had been amputated by an antipersonnel landmine. As soon as we suspected an inhalation injury, we intubated the patient to preserve his airway and started acetylcysteine/heparin aerosol therapy. The patient also was treated with proper antibiotics for right lower lung pneumonia that developed as a sequela of inhalation injury. We could extubate the patient without any complications such as airway obstruction on the third day of intensive care, after which the patient was transferred to the general ward for active rehabilitation. This report presents the first known case of inhalation injury due to a landmine explosion.

Objectives Dilatation of the aortic root structures or ascending aorta is often observed in patients with Fallot type anomalies. We tried to find how fast the aortic structures dilate and how to manage this phenomenon. Methods Among 801 patients who underwent corrective surgery of Fallot type anomalies, [tetralogy of Fallot (TOF) and Fallot type of double outlet right ventricle (DORV)] from 2004 to 2020, 66 patients who had follow-up cardiac computed tomography angiography (CT) images at least over 5-year interval after the initial CT study were enrolled in this retrospective study. We analyzed the diameters and aortic cross-sectional area/height ratio (AH) of aortic annulus, sinus of Valsalva, sinotubular junction and ascending aorta between initial and follow-up CTs. "Dilatation” was defined as a z-score over 2 in each aortic structure. Results The median age at initial and follow-up CTs were 5.9 years (Interquartile range (IQR): 0.4~12.4) and 15.9 years (IQR: 9.3~23.4), respectively. The median CT interval (initial ~ latest CT) was 9.5 years (IQR: 6.6~12.0). Sinus of Valsalva was the aortic structure that dilated the most rapidly (0.94 mm/year) and significantly (32.8 mm at follow-up CT) across the study period. The AH ratio increased significantly in the four aortic structures. Patient’s age was significantly associated with higher AH in follow-up CT. Aortic dilatation was found in 74.2% at initial CT and 86.4% at follow-up CT. Conclusions In Fallot type anomalies, the AH ratio of aortic root structures significantly increased over about 9.5 years. The number of the patients diagnosed within the range of aortic dilatation also increased. Shorter interval for regular follow-up should be considered for these young patients because it could reach a significant dilatation in their mid-20s according to our observation in this study.

A significant growth in demand for online shopping in light of the Coronavirus Disease (COVID) crisis has received attention from transportation practitioners, policy-makers, and researchers. However, an important question arises in this increase in online shopping and resulting deliveries: How long will this last? Very little is known whether this popularity would last a long time. To address this question, the authors conducted a survey of 915 individuals residing in the U.S. and classified them into the four distinctive consumer types (i.e., the prior adopter, temporary adopter and permanent new adopter, and non-adopter) depending on their usage of delivery services before, during, and after (expected) the COVID crisis. This research aims to gain behavioral insight by exploring the differences between the four consumer types and investigating factors affecting the initial adoption and continuance intention of using delivery services. The descriptive analysis revealed that there are clear differences not only between the four types of consumers but also between the four product types (i.e., grocery, food, home goods, and other packages) considered in the survey. The models found that factors affecting the initial adoption and continuance intention are different from the previous studies conducted before the COVID pandemic. Implications for planning and policymaking are also discussed.

This brief introduces a self-biased Scalable Low-Voltage Signaling (SLVS) receiver circuit in order to minimize the power dissipation on D-PHY layer of the Mobile Industry Processor Interface (MIPI). This design does not require any static bias circuitry. It can also support an input common-mode voltage of the receiver as low as 50 mV. This allows D-PHY transmitter to use lower common-mode voltage further reducing the power dissipation of the transceiver pair of D-PHY layer. It is fabricated in a 180-nm CMOS process. The test results show that it operates up to 2 Gbps at 1.2 V power supply in High Speed-mode (HS-mode) of MIPI D-PHY standard. The power efficiency is 92 $\mu \text{W}$ /Gbps or 77 $\mu \text{A}$ /Gbps.

Commercial vehicles are more likely to park close to their destinations than passenger vehicles even though sometimes parking violations are inevitable for their freight or service activities. Although clear distinctions between commercial and passenger vehicles lead to different illegal parking behaviors, little is known about the difference in double parking behaviors between the two types. To better utilize limited curb spaces, a better understanding of differences and similarities is required so that corresponding policies can be established accordingly. Therefore, this research aims to quantify the difference in double parking behavior between commercial and passenger vehicles using count models from two different perspectives: (a) an individual vehicle level count model to investigate vehicle attributes influencing the number of double parking violations per vehicle and (b) a ZIP Code level count model to investigate economic and built environment factors affecting double parking behaviors. The results showed that double parking is a ‘one-time event’ for a passenger vehicle and a ‘recurring event’ for a commercial vehicle. With respect to economic factors, different types of establishments had different levels of impact on double parking for commercial and passenger vehicles in an area. This research discusses how parking policies and strategies can be established based on the similarities and differences between commercial and passenger vehicles’ parking violation behavior.

Background This study aimed to compare long-term outcomes, including durability, after bovine pericardial valve replacement with those after porcine mitral valve replacement (MVR). Methods We enrolled 309 patients who underwent MV replacement (mean age: 65.8±11.5 years; 68.9% females) with Carpentier-Edwards PERIMOUNT bovine pericardial valves (bovine MVR group, n=241) or Hancock II porcine bioprosthesis (porcine MVR group, n=68). The mean clinical and echocardiographic follow-up durations were 81.4±60.0 and 57.8±53.3 months, respectively. Structural valve deterioration (SVD) was defined as prosthetic mitral valve (MV) regurgitation or stenosis of greater than moderate degree combined with a motion limitation, tear, or perforation of prosthetic valve leaflet on follow-up echocardiography. Propensity score (PS)-adjusted multivariable analyses were performed. Results Thirty-day mortality rate was 6.4% (20/309 patients). SVD occurred in 50 patients (33 and 17 patients in the bovine and porcine MV replacement groups, respectively). Cumulative incidences of SVD at 5, 10, and 15 years were 3.2%, 15.9%, and 32.4%, respectively, in the bovine MVR group and 1.9%, 15.3%, and 41.7%, respectively, in the porcine MVR group. Cumulative incidences of SVD in the two groups were not different in competing risk analysis (P=0.23). Other clinical outcomes including overall survival and cumulative incidences of cardiac death and MV-related events were not statistically significantly different between the groups in PS-adjusted multivariable analyses. Conclusions Long-term clinical outcomes including SVD were not different between the bovine and porcine bioprosthesis MVR groups during average 7 years of clinical follow-up after MVR.

Background The COVID‐19 pandemic has disrupted all aspects of healthcare, including cardiothoracic surgery (CTS). We sought to determine the pandemic's impact on CTS trainees' educational experiences. Methods A survey was developed and distributed to members of the Thoracic Surgery Residents Association and other international CTS trainees. Trainees were asked to evaluate their cumulative experiences and share their overall perceptions of how CTS training had been impacted during the earliest months of the COVID‐19 pandemic (i.e., since March 01, 2020). Surveys were distributed and responses were recorded June 25–August 05, 2020. In total, 748 surveys were distributed and 166 responses were received (overall response rate 22.2%). Of these, 126 of 166 responses (75.9%) met inclusion criteria for final analysis. Results Final responses analyzed included 45 of 126 (35.7%) United States (US) and 81 of 126 (64.3%) international trainees, including 101 of 126 (80.2%) senior and 25 of 126 (19.8%) junior trainees. Most respondents (76/126, 43.2%) lost over 1 week in the hospital due to the pandemic. Juniors (12/25, 48.0%) were more likely than seniors (20/101, 19.8%) to be reassigned to COVID‐19‐specific units (p, Cardiothoracic surgery trainees in the United States and abroad have been significantly impacted by the COVID‐19 pandemic in the form of lost time in the hospital, decreased operative volumes, and frequent reassignment to COVID‐19‐specific care settings

In order to find an effective halogen-free flame retardant for acrylonitrile-butadienestyrene copolymer (ABS), organo-phosphorus compounds were studied and their flame retarding performances were determined by UL 94 vertical test. It is found that the flame retardancy strongly depends on phosphorus (P) content of organophosphorus compounds. Only the mixture of ABS with 2-(6-oxido-6Hdibenz< c,e>oxaphosphorin-6-yl) methyl diethyl phosphinate (ODOPM-DE), which has the highest P content, i.e., 17.68 % gives V-0 rating for the 70/30 composition.

Bowel cleansing is a major patient complaint during colonoscopy. Adding laxatives to the bowel preparation is effective in replacing a portion of bowel preparation solution and reducing its volume. Prucalopride is a serotonin receptor agonist that stimulates gastrointestinal motility and provides propulsive force for defecation. This study aimed to compare 1 L polyethylene glycol (PEG) with ascorbic acid (Asc) plus 2 mg prucalopride (1LP/AP) and 2 L PEG with Asc (2LP/A) for colonoscopy preparation with respect to bowel-cleansing quality and side effects.A single-center, randomized, prospective study was conducted with 260 outpatients administered either 1LP/AP or 2LP/A. The primary endpoint was bowel preparation quality, which was evaluated using the Boston Bowel Preparation Scale and Aronchick Bowel Preparation Scale, and the secondary endpoints were patient tolerability and acceptability, assessed by a questionnaire-based survey.The adequate bowel preparation rates were 88.5% and 83.1% in the 2LP/A and 1LP/AP groups, respectively, and the efficacy of 1LP/AP was equivalent to the control regimen (p=.216). Other colonoscopic variables including adenoma detection rate were similar in both groups. Patient tolerability and acceptability were not significantly different, but patients in the 1LP/AP group were more willing to repeat the same regimen (p=.039).Bowel preparation quality with 1LP/AP was equivalent to that with 2LP/A, which did not increase the occurrence of side effects, but it reduced the volume of the solution ingested, and increased patient satisfaction.

Backgrounds: Dilatation of aortic root or ascending aorta is often seen in the patients with conotruncal anomalies (CA). How fast these structures dilate and how we manage this phenomenon are not clear. Methods: We reviewed medical records of patients who underwent biventricular repair of CA such as tetralogy of Fallot (TOF), double outlet right ventricle (DORV) and truncus arteriosus (TA) from 2004 to 2018. We included 99 patients who had follow-up cardiac computed tomography angiography (CT) images at least 5 years since initial CT in this study. We analyzed changes of diameters of aortic root structures and ascending aorta between initial and follow-up CT images. Results: Median follow-up duration was 16.1 years (interquartile range (IQR): 11.8~26.2 years) after operation. Median interval between initial and follow-up CT examination was 9.4 years (IQR: 7.1~11.5 years). Median age of initial and follow-up CT was 4.3 years (IQR: 0.3~12.3 years) and 14.4 years (IQR: 9.2~22.9 years). The median z-scores (with IQR) of sinus of Valsalva (SV, 2.0 (0.8~3.3) → 2.4 (1.4~3.3), p=0.006) and sinotubular junction (STJ, 1.3 (-0.2~2.6) → 2.2 (0.4~3.3), p=0.001) were significantly changed, whereas aortic annulus (AA, 2.4 (0.9~3.4) → 2.3 (0.8~3.3), p=0.21) and ascending aorta (AsA, 1.6 (0.4~2.9) → 1.6 (0.03~2.6), p=0.27) did not show significant changes in CT images. Median increasing rate of diameter of AA, SV, STJ and AsA was 0.72, 0.93, 0.83 and 0.51 mm/year, respectively. Dilatation rate of AA (0.69 in TOF vs. 0.99 in TA, p=0.042) and SV (0.81 in TOF vs. 1.53 in TA, p=0.008) of TA was significantly higher than of TOF. Conclusions: In TOF, DORV and TA, SV and STJ significantly dilated, whereas AsA and AA did not significantly dilated for 9 years of follow-up. Although chance of surgical intervention for dilatation of aortic structures was rare, it might be necessary to observe closely aortic valvular function associated with structural deterioration of SV or STJ.

OBJECTIVES Clinically, tetralogy of Fallot (TOF) patients who underwent repair late (older than 2 years) appears to have worse outcomes after pulmonary valve replacement than patients who underwent repair early. We proceeded to review the clinical features of late-repaired TOF patients who required pulmonary valve replacement. METHODS Fifty patients who underwent pulmonary valve replacement after TOF repair over the age of 2 years from 2000 to 2018 were retrospectively reviewed. Pre- and postoperative cardiac magnetic resonance imaging, cardiopulmonary exercise tests, and cardiac catheterization were analysed. RESULTS The median age of patients at the time of TOF repair and pulmonary valve replacement was 3.6 and 23.4 years, respectively. The median interval from TOF repair to pulmonary valve replacement was 20.5 years. Cardiac magnetic resonance imaging and cardiopulmonary exercise tests were performed at a median of 5.9 and 3.7 years after pulmonary valve replacement, respectively. Cardiac magnetic resonance revealed that there were significant changes in the indexed values of the right ventricle end-diastolic volume (164.7–106.9 ml/m2, P CONCLUSIONS Although pulmonary valve replacement after late TOF correction improves right ventricular volume status, only a minority of patients achieve normalization of right ventricular end systolic volume and a normal functional status.

The estimated mortality rates for breast and cervical cancer in Cambodia are high, perhaps because the Cambodian population lacks information about their detection and prevention. This cross-sectional study assessed the distribution of cervical cancers among and the behavioural and clinical characteristics of Cambodian women. It comprised 1039 Cambodian women who were interviewed between August 2013 and January 2016; the interviews were conducted in person using structured questionnaires. Among the participants, 801 (77.2%) and 709 (68.3%) had heard of cervical cancer and cervical cancer detection tests, respectively. However, 830 (80.2%) had never undergone a Pap smear, and 633 (60.9%) had never heard of breast self-examination. Despite the high mortality rates for breast and cervical cancer in Cambodia, only a small percentage of the participants had risk factors (e.g. smoking, alcohol consumption) for female cancers. A nationwide survey of the knowledge, attitudes and practices related to female cancers is recommended.Impact StatementWhat is already known on this subject? The estimated incidence and mortality rates of breast and cervical cancers in Cambodia are high. How much Cambodian women know about these cancers and whether they are receptive to cancer screening are questions requiring further study.What do the results of this study add? To our knowledge, this is the first study to describe the female cancer-related behavioural and clinical characteristics of Cambodian women. We show that rural Cambodian women are mostly unaware of breast and cervical cancer screening and that only a small percentage had risk factors for these cancers, despite the high incidence of these cancers in Cambodia.What are the implications of these findings for clinical practice and/or further research? Our findings potentially aid the design of programmes that increase awareness of breast and cervical cancers in Cambodia. Such programmes would be expected to reduce the incidence and mortality rates of these cancers in this country. Nationwide screening programmes for female cancers should be implemented in Cambodia.

A frictional torque was generated by a lubricated slip contact between a wet clutch pad and a steel separator during a wet clutch engagement. It is necessary to understand the generation of frictional torque to improve the performance of the frictional torque transfer and the durability of the wet clutch system. The analytical modeling of wet clutch torque transfer considers the effects of surface roughness, permeability, the elastic modulus of the frictional material, lubricant viscosity, temperature, etc. Experimental apparatus for wet clutch engagement was designed for the measurement of frictional torque transfer during wet clutch engagement. The experimental results were compared with the analytical results under various operational conditions for the verification of the theoretical analysis to evaluate the performance of the wet clutch system. Some correlations were investigated between the experimental and analytical results. We found that computation by analytical modeling can predict the effects of oil temperature, applied force, and slip speed, as well as engagement period and frictional torque transfer shapes.

The overuse of oxytetracycline (OTC) in aquaculture has become a problem because of its chronic toxic effects on marine ecosystems. The present study assessed the ecological risk of OTC in the coastal waters near the Jangheung Flatfish Farm using a site-specific multimedia fate model to analyze exposure. Before the model was applied, its performance was validated by comparing it with field data. The coastal waters in the testbed were sampled and analyzed using liquid chromatography-tandem mass spectrometry (LC-MS/MS) followed by solid-phase extraction (SPE). The concentrations of OTC measured varied from 7.05 to 95.39ng/L. The results of validating the models showed that the site-specific multimedia fate model performed better (root mean square error (RMSE): 24.217, index of agreement (IOA): 0.739) than conventional fugacity approaches. This result demonstrated the utility of this model in supporting effective future management of aquaculture effluent. The results of probabilistic risk assessment indicated that OTC from aquaculture effluent did not cause adverse effects, even in a maximum-use scenario.

Recently, numerous studies have utilized graphene in biomedical applications such as drug delivery, cancer therapy, and bioimaging. In this study, graphene was eco-friendly prepared by liquid phase exfoliation of graphite using plant extracts in water. Initially, 12 different plants or plant parts were screened for the characteristic graphene peak at near 268 nm using UV-Vis spectrophotometric analyses. The ability to form stable black graphene dispersion was highest using Xanthium strumarium extract. Transmission electron microscopy images showed that about 5 layer-graphene was produced from 1 g/L of graphite, while more than 5 layers were formed from 2 g/L of graphite. The optimum X. strumarium concentration for graphene production was 2 g/100 mL.

Large DNA molecules are a promising platform for in vitro single-molecule biochemical analysis to investigate DNA-protein interactions by fluorescence microscopy. For many studies, intercalating fluorescent dyes have been primary DNA staining reagents, but they often cause photo-induced DNA breakage as well as structural deformation. As a solution, we previously developed several fluorescent-protein DNA-binding peptides or proteins (FP-DBP) for reversibly staining DNA molecules without structural deformation or photo-induced damage. However, they cannot stain DNA in a condition similar to a physiological salt concentration that most biochemical reactions require. Given these concerns, here we developed a salt-tolerant FP-DBP: truncated transcription activator-like effector (tTALE-FP), which can stain DNA up to 100 mM NaCl. Moreover, we found an interesting phenomenon that the tTALE-FP stained DNA evenly in 1 × TE buffer but showed AT-rich specific patterns from 40 mM to 100 mM NaCl. Using an assay based on fluorescence resonance energy transfer, we demonstrated that this binding pattern is caused by a higher DNA binding affinity of tTALE-FP for AT-rich compared to GC-rich regions. Finally, we used tTALE-FP in a single molecule fluorescence assay to monitor real-time restriction enzyme digestion of single DNA molecules. Altogether, our results demonstrate that this protein can provide a useful alternative as a DNA stain over intercalators.

With advances in information technology, online shopping for a parcel (retail), grocery, and food (i.e. prepared meal) have become a part of daily life and they are expected to continue to grow in the future. Accordingly, shopping behaviors, i.e. shopping channels, are becoming more complex than ever. However, the current research focus is still mainly on traditional parcel delivery and little is known for food and grocery deliveries and their impacts on transportation systems. To have a better understanding of deliveries and their impacts on transportation systems, using the survey data from NYC DOT Citywide Mobility Survey in 2018, this paper investigated (a) factors affecting the three types of deliveries (retail, grocery, and food) by developing a seemingly unrelated model, and (b) the relationships between deliveries and in-store shopping trips by different modes using multiple simultaneous equations models. The results showed that factors affecting deliveries vary by the type of delivery, and the three deliveries are positively correlated by common unobserved factors. In addition, the relationships between delivery and shopping trip vary not only by delivery type but also by trip mode (driving/walking). The findings would provide valuable insights into travel demand modeling and curbside management.

Chemical spill accidents lead to environmental problems, especially for plants. Plant vegetation assessment is necessary after a chemical accident; however, conventional methods can be inaccurate and time-consuming. This study used the vegetation index (VI) extracted from unmanned aerial vehicle (UAV) multispectral imagery for crop damage assessment after chemical exposure. The chemical accident simulations were conducted by exposure of rice at five growth stages to four levels of toluene. The VI was measured at five days after damage and 67 days after planting. Physiological characteristics (chlorophyll content and grain yield) were also measured. As a result, the mean normalized difference VI (NDVI) of toluene-exposed rice was significantly decreased with respect to toluene exposure concentration increases at most growth stages. Recovery after toluene exposure was lower in rice exposed to higher concentrations at the earlier growth stages. The chlorophyll content and grain yield were also decreased after toluene exposure with respect to increasing toluene concentrations and showed positive correlations with the NDVI. It indicates that the NDVI is capable of reflecting the plant response to chemical exposure. Thus, the results demonstrated that the VI based on UAV multispectral imagery is feasible as an alternative for crop monitoring, damage assessment after chemical exposure, and yield prediction.

Engine torque is transferred to the transmission where drag torque is minimized improving fuel efficiency. This is particularly true in a wet clutch pack. This study measures slip friction when the wet clutch pack in a DCT (Dual-Clutch Transmission) is disengaged, and the friction pads are slipping. Shudder engagement velocity, and applied forces can be measured under various working conditions through these torque transfer experiments. Test results demonstrate that the design parameters, and engagement conditions of wet clutch packs can be optimized to reduce shudder and frictional vibration during engagement in a dual clutch transmission. Key words : Wet clutch(습식클러치), Dual clutch(듀얼클러치), Sliding friction(미끄럼마찰), Shudder(떨림), Frictional vibration(진동), Torque transfer(토크변화), DCT(듀얼클러치 변속기) Nomenclature 1)   : apply force  : separate plate inertia  : fly wheel inertia  : apply pressure on the piston  : friction plate of inner radius  : friction plate of outer radius 

A series of novel organo-phosphorus compounds was synthesized from 9,10-dihydro-9-oxa-10-phosphaphenanthrene- 10-oxide (DOPO) in an attempt to obtain high phosphorus (P) containing halogen-free flame retardant (FR). The success of synthesis was confirmed by 1H and 31P NMR spectra. The P content of FR varied from 12.95 to 19.22 wt%. Thermal stabilities of synthesized FRs and their flame retardancy for Acrylonitrile-Butadiene- Styrene copolymer (ABS) were investigated by thermal gravimetric analysis (TGA) and the classification of UL-94 V-0 rating, respectively. 27.5-30.0 wt% FR loadings gave the V-0 rating for the ABS/FR mixtures and no fume emission was observed. It was found that the flame retardancy strongly depends on the P content of FR and 5.03-5.30 wt% P is required in the formulation to exhibit self-extinguishing ability when phosphinate or phosphonate FRs are employed. The mode of flame retardancy action is also discussed.

We investigated the prognosis of patients with dry pleural dissemination (DPD) of non-small cell lung cancer (NSCLC) and the risk factors of developing to malignant pleural effusion (MPE).We retrospectively reviewed 104 patients with NSCLC and DPD, confirmed surgically from 1996 to 2016. Incidence rate and risk factors of MPE were analyzed statistically. The prognosis of NSCLC patients with MPE was evaluated using the Kaplan-Meier method.The most common histologic type was adenocarcinoma in 95 (91.3%) patients. The median follow-up duration was 65.5 months and the median survival time was 37.7 months. MPE developed in 51 (49%) patients, and the median effusion-free interval was 41.9 months. The median survival time of the patients with and without MPE was not different (41.3 vs 31.7 months, P = .16). No predictive factors for the development of MPE were identified. Fifteen (14.4%) patients underwent invasive procedures for the management of MPE.Almost half of all patients with NSCLC and DPD experienced MPE, and 14.4% patients developed symptomatic MPE requiring invasive procedures. MPE in DPD did not affect the survival in NSCLC patients.

Secure naming systems, or more narrowly public key infrastructures (PKIs), form the basis of secure communications over insecure networks. All security guarantees against active attackers come from a trustworthy binding between user-facing names, such as domain names, to cryptographic identities, such as public keys. By offering a secure, distributed ledger with highly decentralized trust, blockchains such as Bitcoin show promise as the root of trust for naming systems with no central trusted parties. PKIs based upon blockchains, such as Namecoin and Blockstack, have greatly improved security and resilience compared to traditional centralized PKIs. Yet blockchain PKIs tend to significantly sacrifice scalability and flexibility in pursuit of decentralization, hindering large-scale deployability on the Internet. We propose Conifer, a novel PKI with an architecture based upon CONIKS, a centralized transparency-based PKI, and Catena, a blockchain-agnostic way of embedding a permissioned log, but with a different lookup strategy. In doing so, Conifer achieves decentralized trust with security at least as strong as existing blockchain-based naming systems, yet without sacrificing the flexibility and performance typically found in centralized PKIs. We also present our reference implementation of Conifer, demonstrating how it can easily be integrated into applications. Finally, we use experiments to evaluate the performance of Conifer compared with other naming systems, both centralized and blockchain-based, demonstrating that it incurs only a modest overhead compared to traditional centralized-trust systems while being far more scalable and performant than purely blockchain-based solutions.

A series of novel organo-phosphorus flame retardants (FR) derived from 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide (DOPO) have been synthesized in order to investigate their flame retarding performances for acrylonitrile-butadiene-styrene copolymer (ABS). The success of synthesis was confirmed by 1H and 31P NMR. The flame retardancy performances evaluated by UL-94V test revealed that V-0 ratings are achieved when 27.5–30.0 wt% of FRs are added to the ABS/FR mixtures. The most dominating factors affecting the flame retardancy of phosphorus containing FR are the phosphorus (P) content in the mixture and the chemical structure of FR incorporated. It was found that 4.86–5.05 wt% P in the formulation is required to exhibit self-extinguishing ability when phosphinate or phophonate FRs are employed. On the other hand, no rating is obtained for phosphate type FR containing mixture even though higher amount of P, that is, 5.07 wt% is present in the mixture, indicating that oxidation state of the phosphorus element in FR is very important in governing the flame retardancy. The modes of actions of FRs in terms of gas versus condensed phase are also discussed. Thermogravimetric analysis (TGA) results showed that the FR containing compounds possess inferior thermal stability compared to neat ABS at the beginning of decomposition, suggesting that the thermal degradation of ABS is accelerated by the presence of FR at earlier stage of degradation and then hindered by the char formed at later stage of degradation.

Huyndai Powertech, Co. Namyang, Korea(Received March 7, 2014 ; Revised May 13, 2014 ; Accepted May 14, 2014)Abstract − Frictional heat greatly influences the friction behaviors during clutch engagement. Therefore, theengagement of a wet or dry clutch is frequently not under control by the frictional heat. In a wet clutch, the fric-tional temperature also specially needs to be controlled, and in many cases, the clutch material is selected to pre-vent a temperature rise from the friction between friction pad and separator. However, only the selection of theclutch material cannot ensure sufficient control of the temperature rise by the friction. The groove pattern on afriction pad is designed for more flow rates of transmission fluid between the contact gap of clutch pad and sep-arator for the cooling effect. In this work, grove patterns are designed for more flow rates out of the contact gapbetween friction pad and separator plate. Selected groove design shows the improvement flow rates of trans-mission fluid through both inner and outer radius, where most of the transmission fluid flows through the outerradius when the clutch is engaged due to the centrifugal force in conventional wet clutch groove. Several com-parisons of the amounts of frictional heat generated on clutch pads are made in order to verify the decrease ofthe temperature rise according to the flow rates along the groove patterns.Keywords − clutch engagement (클러치 체결), frictional heat (마찰열), groove pattern (그루브 패턴), heatconductio (열전도), transmissio fluid (TF, 변속기 오일), wet clutch (습식클러치)

Korea Powertrain, Co., Daegu, Korea(Received December 27, 2013 ; Revised February 25, 2014 ; Accepted February 28, 2014)Abstract − Transmission fluid film behaviors in the gap between the wet clutch pad and separator plate are ana-lyzed using the CFD software ADINA. Three pattern groove designs are selected and are used to validate thefluid film behaviors based on the outlet flow in the gap when the wet clutch pad and separator plate are engaged.The main design goal for pattern grooves is faster engagement. In most cases, much of the outlet flow of trans-mission fluid in the gap occurs on the outer radius boundary due to the centrifugal force generated by the clutchpad circular motion. Groove patterns are created to ensure faster transmission fluid outlet flow in the directionof the inner radius boundary. Computational results of the selected groove patterns are compared.Keywords − clutch engagement (클러치 체결), friction pad (마찰패드 ), groove pattern (그루브 패턴 ), transmissionfluid (TF, 변속기 오일), wet clutch (습식클러치)