Three Essays in Law and Economics: Consequences and Formation of Legal Rules in Other Markets

In this thesis, I study the consequences and formation of legal rules in the “non-traditional” markets to show that non-traditional markets are fundamental to a society’s functioning. The first chapter shows how legal participants strategically behave based on judicial disqualification. The second chapter examines the unintended consequence of a decarceration policy in the criminal-justice system by linking the ex-criminal re-entry issue and homelessness. Lastly, the third chapter concentrates on how the tenure of elected law enforcement agents contributes to the jail-crowding environment, leveraging term limits imposed on local county elected officials. The first chapter examines the use and impact of peremptory challenges against judges in the California courts. Under California law, a judge cannot preside in a case when the judge is prejudiced against a party or attorneys who are involved in the case. A “peremptory” challenge does not require an attorney to show cause, such as a judge who has a personal interest in the case, nor is it necessary for the party requesting the peremptory challenge to prove that the judge is biased. Moreover, no factual basis for the claim of bias is even required. The party simply has to state that he or she believes the judge is prejudiced against him or her and that they do not believe they can receive a fair trial. Finally, judges cannot oppose challenges made in a timely manner. Upon the filing of a peremptory-challenge motion, the judge loses control of the case, and any rulings are voided. The major difference with peremptory challenges in juries is that in the case of judges, each side of the case is allowed only one peremptory challenge. This work bases the decision to challenge on the likelihood a potential replacement judge who could be randomly assigned the case if the attorney challenges the judge is more likely to be favorable to the challenger side of the case. The results show that peremptory challenges are used strategically to remove judges when the replacement is more likely to be against the opponent’s preferences in terms of ideology or past rulings on motions. The second chapter examines the effect of re-sentencing policies as a means of decarceration on community well-being. In 2011 and 2014, California passed jail decarceration policies, AB 109 and Prop 47, respectively. AB 109 reallocated state prison inmates into local county jails. On the other hand, Prop 47 reduced penalties for non-serious property crimes, thereby providing a second chance for offenders who committed specific non-violent crimes, while lowering the burden on county jails by shifting offenders into local communities. My results indicate that Prop 47 increased the homeless population and health-related governmental spending but did not reduce governmental spending on corrections. Furthermore, California jail-disposition data show heterogeneous effects on recidivism. For example, Prop 47 decreased recidivism rates for Prop 47 charges (non-serious and non-violent charges) after AB 109 increased the rates in county jails. However, Prop 47 failed to lower recidivism rates for control-group charges (more severe than Prop 47 charges) after AB 109 raised these rates in county jails. Finally, I find that Prop 47 raised non-violent crime rates, utilizing Los Angeles crime data, especially among non-homeless offenders. The third chapter strives to find the cause of jail and prison overcrowding. Calls for criminal justice reform have become commonplace, as issues ranging from ethnic and racial bias in policing to prison overcrowding have taken center stage in many policy discussions. The demand for change in the criminal justice system largely falls on the shoulders of leadership within the criminal justice system who might have their own preferences toward criminal justice reform. This work examines the issue of sheriff tenure on jail occupancy rates, as jails are directly managed by the sheriff and capacity issues in jails have resulted not only in safety and security problems for inmates and staff but also in fiscal stress. Utilizing a unique institutional feature - that 192 county sheriffs are limited to no more than two terms in the position - the work employs an instrumental variable identification strategy to examine the impact of sheriff tenure on jail occupancy rates

Tapered catheter-based transurethral photoacoustic and ultrasonic endoscopy of the urinary system

Early diagnosis is critical for treating bladder cancer, as this cancer is very aggressive and lethal if detected too late. To address this important clinical issue, a photoacoustic tomography (PAT)-based transabdominal imaging approach was suggested in previous reports, in which its in vivo feasibility was also demonstrated based on a small animal model. However, successful translation of this approach to real clinical settings would be challenging because the human bladder is located at a depth that far exceeds the typical penetration depth of PAT (???3 cm for in vivo cases). In this study, we developed a tapered catheter-based, transurethral photoacoustic and ultrasonic endoscopic probe with a 2.8 mm outer diameter to investigate whether the well-known benefits of PAT can be harnessed to resolve unmet urological issues, including early diagnosis of bladder cancer. To demonstrate the in vivo imaging capability of the proposed imaging probe, we performed a rabbit model-based urinary system imaging experiment and acquired a 3D microvasculature map distributed in the wall of the urinary system, which is a first in PAT, to the best of our knowledge. We believe that the results strongly support the use of this transurethral imaging approach as a feasible strategy for addressing urological diagnosis issues

Antagonistic Bacillus species as a biological control of ginseng root rot caused by Fusarium cf. incarnatum

Background: This study aimed to develop a biocontrol system for ginseng root rot caused by Fusarium cf. incarnatum. Methods: In total, 392 bacteria isolated from ginseng roots and various soils were screened for their antifungal activity against the fungal pathogen, and a bacterial isolate (B2-5) was selected as a promising candidate for the biocontrol because of the strong antagonistic activity of the bacterial cell suspension and culture filtrate against pathogen. Results: The bacterial isolate B2-5 displayed an enhanced inhibitory activity against the pathogen mycelial growth with a temperature increase to 25°C, produced no pectinase (related to root rotting) and no critical rot symptoms at low [106 colony-forming units (CFU)/mL] and high (108 CFU/mL) inoculum concentrations. In pot experiments, pretreatment with the bacterial isolate in the presumed optimal time for disease control reduced disease severity significantly with a higher control efficacy at an inoculum concentration of 106 CFU/mL than at 108 CFU/mL. The establishment and colonization ability of the bacterial isolates on the ginseng rhizosphere appeared to be higher when both the bacterial isolate and the pathogen were coinoculated than when the bacterial isolate was inoculated alone, suggesting its target-oriented biocontrol activity against the pathogen. Scanning electron microscopy showed that the pathogen hyphae were twisted and shriveled by the bacterial treatment, which may be a symptom of direct damage by antifungal substances. Conclusion: All of these results suggest that the bacterial isolate has good potential as a microbial agent for the biocontrol of the ginseng root rot caused by F. cf. incarnatum

Recommendation Framework Combining User Interests with Fashion Trends in Apparel Online Shopping

Although fashion-related products account for most of the online shopping categories, it becomes more difficult for users to search and find products matching their taste and needs as the number of items available online increases explosively. Personalized recommendation of items is the best method for both reducing user effort on searching for items and expanding sales opportunity for sellers. Unfortunately, experimental studies and research on fashion item recommendation for online shopping users are lacking. In this paper, we propose a novel recommendation framework suitable for online apparel items. To overcome the rating sparsity problem of online apparel datasets, we derive implicit ratings from user log data and generate predicted ratings for item clusters by user-based collaborative filtering. The ratings are combined with a network constructed by an item click trend, which serves as a personalized recommendation through a random walk. An empirical evaluation on a large-scale real-world dataset obtained from an apparel retailer demonstrates the effectiveness of our method

Design of Self-Reporting Liquid Crystals for Food Poisoning Bacteria

Sensitive and selective detection of salmonella that causes food-borne diseases is necessary for food safety and prevention of pathogenic infection. However, previous methods require laborious and time consuming process. Here, we offer simple approach to realize rapid detection of food poisoning bacteria (salmonella) by integrating extraordinary sensitivity of liquid crystals (LCs) and selectivity of organic ionics (OIs). Specifically, self-assembled OI at the aqueous interface of LC film cause vertical LC ordering. Under the incubation of LC in the aqueous solution with tryptone, however, we observe the formation and growth of birefringent domains after ~1.5 hours. Surprisingly, we observe the presence of salmonella to facilitate the formation of domains, which is dependent on salmonella population. We demonstrated the OI-LC system enables rapid detection of target bacteria within 20 min without any complex procedure. This work was supported by NRF-2021R1A4A1030944 & 2021R1A2C20950102

Ultra-High Energy Density Hybrid Supercapacitors Using MnO2/Reduced Graphene Oxide Hybrid Nanoscrolls

Manganese oxide (MnO2) is a promising material for supercapacitor applications, with a theoretical ultra-high energy density of 308 Wh/kg. However, such ultra-high energy density has not been achieved experimentally in MnO2-based supercapacitors because of several practical issues, such as low electrical conductivity of MnO2, incomplete utilization of MnO2, and dissolution of MnO2. The present study investigates the potential of MnO2/reduced graphene oxide (rGO) hybrid nanoscroll (GMS) structures as electrode material for overcoming the difficulties and for developing ultra-high-energy storage systems. A hybrid supercapacitor, comprising MnO2/rGO nanoscrolls as anode material and activated carbon (AC) as a cathode, is fabricated. The GMS/AC hybrid supercapacitor exhibited enhanced energy density, superior rate performance, and promising Li storage capability that bridged the energy–density gap between conventional Li-ion batteries (LIBs) and supercapacitors. The fabricated GMS/AC hybrid supercapacitor demonstrates an ultra-high lithium discharge capacity of 2040 mAh/g. The GMS/AC cell delivered a maximum energy density of 105.3 Wh/kg and a corresponding power density of 308.1 W/kg. It also delivered an energy density of 42.77 Wh/kg at a power density as high as 30,800 W/kg. Our GMS/AC cell’s energy density values are very high compared with those of other reported values of graphene-based hybrid structures. The GMS structures offer significant potential as an electrode material for energy-storage systems and can also enhance the performance of the other electrode materials for LIBs and hybrid supercapacitors

Selective Chemical Report based on Liquid Crystals integrated with Organic Ionics

Liquid crystals (LCs), which have amplification property by anisotropic nature and long-range molecular ordering, lead molecular scale interaction to be magnified to visible scale [1]. Therefore, LCs have been used for reporting a variety of chemical stimuli. However, the relatively low selectivity to specific chemicals was pointed out as a problem. Here we propose versatile design rules to control not only selectivity but sensitivity by decorating the interface with organic ionics (OIs). We demonstrated the OI-LC film immediately reacts and optically reports the exposure of a specific gas molecule (acetic acid) at very low concentration (< 1 ppm). We confirmed LC molecule electrostatically and physically interacts with OI causing vertical orientation of the LC film. In the exposure of acetic acid, however, carboxylic group interrupts the existing interaction, changing LC orientation. Furthermore, we showed their characteristics are controllable by modulating the length of carbon chain and type of counter ion in OIs. Computational simulation represents good agreement with our experimentally proposed mechanism. This work was supported by the NRF (2021R1A4A1030944 & 2021R1A2C2095010)2

Design of Liquid Crystal Based Self-Reporting System for Food Poisoning Bacteria

Sensitive, selective, and rapid detection of salmonella which causes food-borne diseases is required in terms of food safety and prevention of pathogenic infection. However, previous methods like polymerase chain reaction (PCR) and enzyme-linked immunosorbent assay (ELISA) require laborious and time-consuming process, and trained personnel. In this work, we offer simple and generalizable approach to realize rapid detection of specific food poisoning bacteria (salmonella) by liquid crystals (LCs) based system integrated with organic ionics (OIs). Specifically, OIs are self-assembled at the aqueous-LC interface and cause vertical LC ordering. Under the incubation of the LCs in the aqueous solution with peptides, however, we observe gradually reoriented LC, which leads to the formation and growth of birefringent domains after ~1.5 hours. Surprisingly, we observe the presence of salmonella to facilitate the formation of domains and their grow rate is dependent on the population of salmonella, which enables the rapid detection of target bacteria within 20 min without any complicated procedure. This work was supported by NRF-2021R1A4A1030944&2021R1A2C20950102

Tailoring of Selective Chemical Reaction via Liquid Crystals Integrated with Organic Ionics

Liquid crystals (LCs) have been used for reporting a variety of chemical reactions via the amplification ability resulting from the combination of anisotropic nature and long-range molecular ordering.1 However, the relatively low selectivity to specific chemicals has hindered their potential. Here, we propose simple and versatile design rules to control not only selectivity but sensitivity by decorating the interface with organic ionics (OIs). We demonstrated the OI-LC film to immediately sense and optically report the exposure of a specific gas molecule (acetic acid) at very low concentration (< 1 ppm) by electrostatic interaction of the head group of OI to specific functional group. Furthermore, we showed their characteristics are controllable by modulating the length of carbon chain and type of counter ion in OIs. The results represent a good agreement between the experimental and theoretical exploration. This work was supported by the NRF (2021R1A4A1030944 & 2021R1A2C2095010)2

Reduced Computational Complexity Orthogonal Matching Pursuit Using a Novel Partitioned Inversion Technique for Compressive Sensing

This paper reports a field-programmable gate array (FPGA) design of compressed sensing (CS) using the orthogonal matching pursuit (OMP) algorithm. While solving the least-squares (LS) problem in the OMP algorithm, the complexity of the matrix inversion operation at every loop is reduced by the proposed partitioned inversion that utilizes the inversion result in the previous iteration. By the proposed matrix (n &times; n) inversion method inside the OMP, the number of operations is reduced down from O(n3) to O(n2). The OMP algorithm is implemented with a Xilinx Kintex UltraScale. The architecture with the proposed partitioned inversion involves 722 less DSP48E compared with the conventional method. It operates with a sample period of 4 ns, signal reconstruction time of 27 &mu;s, and peak signal to noise ratio (PSNR) of 30.26 dB